PREPARING GRAIN FOR STORAGE
VOLUME I OF
SMALL FARM GRAIN STORAGE
CARL LINDBLAD, PEACE CORPS
LAUREL DRUBEN, VITA
VOLUNTEERS IN TECHNICAL
PROGRAM & TRAINING JOURNAL
MANUAL SERIES NUMBER 2
MANUAL SERIES NUMBER 35E
FIRST PRINTING SEPTEMBER 1976
THREE VOLUMES JULY 1977
THIRD PRINTING JULY 1980
Wilson Boulevard, Suite 500
Arlington, Virginia 22209 USA
Tel: 703/276-1800 * Fax:
TABLE OF CONTENTS
The Purpose of
The People Who
Prepared This Manual
How To Use This
SECTION 1: THE GRAIN
Storage Is Important to Farmers
Grain Is a
What Happens to
Grain in Storage
Storage Depends Upon Better Drying and Better Storing
Storage Helps Farmers"
SECTION 2: GRAIN IS
A LIVING THING
of Grain and How They Affect Storage
"Grain Is a
SECTION 3: GRAIN,
MOISTURE, AND AIR
Moisture in the
Moisture, and Grain Interact
Levels in Grain
Moisture in Stored Grain
Where You Are
SECTION 4: PREPARING
GRAIN FOR STORAGE
The Need for
for Moisture Content
Grain for Storage"
SECTION 5: GRAIN
Using Plastic Sheets
Maize Drying and Storage Crib
Newer Drying Methods
A Simple Oil
for Using the Oil Barrel Dryers
The Pit Oil
Dryers: Part 1:
Different Ways to Present Grain Storage
Information on Moisture Meters
APPENDIX C: Working
Paper on the Volunteer Role in Grain
Storage: "Problems Related
to Popularizing New
Farm-level Grain Storage Technology"
Bibliography: Reprint of
Listings Prepared by
Tropical Products Institute, London
PURPOSE OF THE MANUAL
Small Farm Grain Storage is a set of how-to manuals.
volumes provide a comprehensive overview of storage problems
considerations as they relate to the small farmer.
recommend the volumes be purchased as a set because the
an excellent and complete working and teaching tool for
workers in the field.
This grain storage information can be adapted
easily to meet on-the-job needs; it has already been used as
basis for a grain storage workshop and seminar in East
This set of publications retains the purpose of the original
to bring together and to communicate effectively to field
1) the basic principles of grain storage and 2) the
currently being used and tested around the world to combat
grain storage problems.
Only the format has been changed to:
reduce printing and postage costs.
permit updating and revising one volume at a
provide smaller books that are easier to
hold and use
than the large,
make portions of the information available
to the user
who is especially
interested in only one or another of
the major aspects
of small farm grain storage.
Of course, it is impossible to cover all storage situations
manual. But farmers
who understand the basic, unchanging principles
of drying and storing grain are better able to adapt ideas,
and technologies from other parts of the world to their own
This material was prepared for use by those who work to
OVERVIEW OF THE MANUAL
Volume I, "Preparing Grain for Storage," discusses
problems as they are faced by small-scale farmers.
contains explanations of the structure of grain, the
between grain and moisture, the need for proper drying.
section contains detailed, fully illustrated plans for
a variety of small-scale grain dryers.
Volume II, "Enemies of Stored Grain," is an
in-depth study of two
insects and rodents. Each is
discussed in detail
with guidelines for 1) defining the size of the problem and
grain by both chemical and non-chemical means.
includes dose and use information for a variety of
pesticides, as well
as suggestions for preparing materials to be used in
Volume III, "Storage Methods," contains a survey
of storage facilities
from the most traditional basket-type granary to metal bins
silos. The emphasis
in this volume is on improving existing facilities;
for example, there are detailed construction procedures for
improved mud silo.
Storage in underground pits and sacks also is
discussed. There are
guidelines for using insecticides in storage
largest silo presented in detail is the 4.5 ton
cement stave silo.
PEOPLE WHO PREPARED THIS MANUAL
Carl Lindblad served as a Peace Corps Volunteer in Dahomey
from 1972 to 1975.
As a Volunteer, Lindblad worked in programs
designed to introduce and popularize a variety of grain
his return to the United States, he began the task
of pulling together this manual as a consultant to VITA and
Corps. At present,
he serves as a consultant to a number of international
organizations, specializing in appropriate technologies for
grain storage -- in the areas of planning, extension and
He spends much of his time in the field.
Laurel Druben served as an International Voluntary Services,
Volunteer in Laos from 1966 to 1968.
While in Laos she was a
curriculum planner and a teacher of English as a second
Subsequently, she worked with a consulting firm evaluating
research and development projects, ran a small
business, and was a free-lance consultant and proposal
writer. Druben, who
has worked and lived in India and Micronesia,
as well as Southeast Asia, is Director of Communications for
Many thanks are due to the skilled and concerned people who
make this manual possible:
A number of VITA
people provided technical review, artwork,
-- John Goodell
Section 4, Vol. I
materials -- Frederick Bueche
-- Douglas Barnes, Merle Esmay, Henry Highland,
Larry Van Fossen, Harold Willson,
Artwork -- George
Clark, John Goodell, Kenneth Lloyd,
Nicholas Reinhardt, Guy Welch
extended to the following individuals and institutions
invaluable assistance in early stages of work on
Mary Ernsberger and Margot Aronson, Peace
Corps Program and
Peace Corps Information Collection & Exchange, USA
Products Center, TPI, Great Britain
Henry Barre and
Floyd Herum, Agricultural Engineering Department,
Grain Science and Industry, Kansas State University,
Research Service, Department of Agriculture, USA
Implementation Department, Ministry of
F. W. Bennett,
Midwest Research Institute, USA
Agricultural Credit Programs (SACP), Belize
Agricultural Cooperatives Development International
Assistance Bureau, US Agency for International
Development Research Center, University of Alberta,
International Food Education (LIFE), USA
Recherches Agronomiques Tropicales et des Cultures
Protection Project, University of Hawaii, USA
Engineering Service, FAO
Storage Center, IITA, Nigeria
Agricultural Research, Ahmadu Bello University,
Grain Storage Project
Food Technology and Nutrition Section, UNICEF, Kenya
Centre Nationale de Recherches Agronomiques (CNRA),
R. A. Boxall,
Indian Grain Storage Institute, A.P., India
Boon-Long, Ministry of Agriculture and Cooperation,
of Technology, Chulalongkorn University, Thailand
Bangladesh Agricultural Research Council
Rice Research Institute (IRRI), Philippines
Dante de Padua,
University of Los Banos, Philippines
THE SPONSORING ORGANIZATIONS
Small Farm Grain Storage is part of a series of publications
Peace Corps practical field experience with VITA technical
in areas in which development workers have special
finding useful resource materials.
Since 1961 Peace Corps Volunteers have worked at the
in countries around the world in program areas such as
public health, and education.
Before beginning their two-year
assignments, Volunteers are given training in
and language skills.
This training helps them to live and work
closely with the people of their host countries.
It helps them, too,
to approach development problems with new ideas that make
locally available resources and are appropriate to the local
Recently Peace Corps established an Information Collection
Exchange, so that these ideas developed during service in
could be made available to the wide range of development
might find them useful.
Materials from the field are now being
collected, reviewed, and classified in the Information
Exchange system. The
most useful materials will be shared with the
The Information Collection and Exchange provides
an important source of field-based research materials for
of how-to manuals such as Small Farm Grain Storage.
VITA people are specialists who volunteer their free time to
requests for technical assistance.
Many VITA Volunteers have lived
and worked in other countries, often as Peace Corps
VITA people now work in the United States and other
countries where they are engineers, doctors, scientists,
architects, writers, artists, and so on.
But they continue to work
with people in other countries through VITA.
VITA Volunteers have
been providing technical assistance to the Third World for
Requests for assistance come to VITA from many nations.
is handled by a Volunteer with the right skills.
For example, a
question about grain storage in Latin America might be
handled by a
professor of agriculture, and a request for an improved
implement would go to an agricultural engineer.
These VITA Volunteers,
many of whom have lived and worked in Third World countries,
familiar with the special problems of these areas and are
able to give
useful, and appropriate, answers.
VITA makes the expertise of VITA people available to a wide
through its publications program.
HOW TO USE THIS MANUAL
Development workers can use material from this manual in a
The manual provides clear presentations of grain
principles from which you can take material to lead
discussions with farmers and village
There are suggestions for demonstrations and
which you might find helpful to illustrate grain
principles to farmers.
Some of the material has been prepared in the form
illustrated leaflets which can be used directly by you
farmer. They may require little or no
But, if you prefer, you can use the
structure of the
substitute photographs specific to your area.
on rodent control in Volume II is a good example
of this kind
Many of the construction plans have been
so that you will be able to work more closely with
farmer. Some of the plans are fully
photographs of the work steps showing conditions in
area. It is likely that after you
introduce the material,
follow the instructions themselves. The
written so that they would be easy to translate
languages. The Improved Maize Drying
Volume I is
a good example of a step-by-step, illustrated
Some of the material most likely to be useful for
farmers has been simplified and prepared in checklist
form. This material would lend itself to
illustrations or photographs, so it can better fit into the
situation. The checklists on
controlling grain storage
included in Volume II are in this category.
The appendices contain examples of leaflets that
prepared by development workers in several countries.
examples have been included to give you some
idea of how
the materials in this manual might be organized,
translated, and presented to reach farmers.
Wherever possible, addresses are given so that you
for more information on a subject.
Other appendices contain information on
areas which, although important, cannot be
covered fully within
the scope of
this manual, for example, storage program
planning. A bibliography is
provided at the end of each volume.
These are some of the aims of Small Farm Grain Storage.
probably find added uses.
While it is not possible to make this
manual specific to the situations or culture of your
the information is presented so that you can do this very
making additions or substitutions to the material.
Dimensions are given in metric units in the text and
Conversion tables are provided at the end of each volume.
This manual will grow and change as its readers and users
additional material, comments, and ideas for new approaches
storage problems and better ways to communicate with
own ideas and conclusions are welcome.
A form has been included for
Please send us the results of your silo or dryer
building. Let us
know how you used the information and how it could
be make even more useful to you.
Tell us how you changed a plan to
fit local needs.
Your experience will help us to produce manuals of growing
to the world-wide development community.
For your convenience, a reply form has been inserted
send it in and let us know how the manual has helped or can
more helpful. If the
reply form is missing from your book, just put
your comments, suggestions, descriptions of problems, etc.,
piece of paper and send them to:
3706 RHODE ISLAND AVENUE
MT. RAINIER, MD 20822
THE GRAIN STORAGE PROBLEM
Farmers all over the world lose much of
their grain after it is harvested.
work hard to plant and grow crops.
often they do not receive good returns
for their time and effort.
The grain is
attacked in the field and in storage by
insects, rodents, birds, and other pests.
The grain that pests do not eat, they
dirty with their droppings and their bodies.
Farmers have lived with these problems
for hundreds of years.
So they have
developed ways to deal with them.
Many old ways are wasteful, but a
number of the old methods are good
and must be kept until they can be
replaced or improved.
In recent years, however, the grain
storage problem has changed (and, in
some cases, temporarily worsened) as
steps toward full development have
been taken. For
example, now there
are new seed varieties which grow faster
and yield more grain.
Farmers plant these
new seeds, and this grain is ready for
harvesting earlier than it used to be.
This grain is ready to be harvested during
the rainy season.
The farmer has always
dried his crops in the sun, but there may
be little sun during this season.
it is likely this new variety of grain must
not be left to dry in the field:
grain dries too long in the field, it will
shatter (break). But
if the farmer brings
the grain from the field and stores it
before bringing the moisture content of
the grain down to 13% or lower, the grain
will rot and mold.
The farmer must find a way to dry his grain,
store it safely, and plant another crop -- all
in the time he used to spend on one crop.
His many old methods must be changed to help
with new problems.
The basic question then is how to help farmers protect their
attack. The answer
must be to give the farmer enough information about
harvesting, drying, storing, insects, rodents, and molds so
that he can
fight the problems successfully.
No one can find answers to problems
without having enough information about the subject.
Farmers need to know that there are steps they can take to
own grain. Perhaps a
farmer can save significant quantities of grain
by making a simple change in the way he is doing things
there is another way of drying or of storing which fits into
well. A farmer needs
to be presented with ideas that can be demonstrated,
that make sense to him, and that fit into his life
easily. This is done
by supplying technology and help which is appropriate.
With this kind
of help, change for the better is more likely to take place.
The following chapters offer many ideas about the grain
The materials have been prepared to make them easy for you
in your work. The
manual should help you get information to those
who can use it.
GOOD GRAIN STORAGE IS IMPORTANT TO FARMERS
When people in universities and government agencies talk
they are discussing a serious subject.
They talk about such facts as
approximately 30% of grain in storage all
over the world is
because of insects, rodents, and molds.
improving grain storage would mean less
the individual, and a higher standard of living
and a sounder
economy for the nation.
quality grain for international trade is of
improper storage of grain leads to weight
loss, quality loss, food loss.
These concerns are real.
And there is a definite need for people to
deal with grain storage questions at this level.
Many new ideas and
plans result from the testing, thinking, and planning being
over the world by scientists, teachers, and researchers.
But when small farmers talk about grain storage problems,
talking about their livelihood.
And there are some very important
reasons why grain storage questions are of concern to them.
Food for the Family
Grain is very likely the single most important
thing eaten by the farmer and his family.
Whether it is maize, wheat, rice, millet, or
sorghum, it is important for his family.
farmer may not think about grain losses and
use words like quality and quantity.
can see that insects, rodents, and molds ruin
a lot of his grain, and that there is not as
much for his family to eat.
He can taste
the difference between clean grain and grain
which has been damaged by mold.
the loss of grain and the need for better
storage when they run out of grain for food
before the next harvest.
Then they must use
what little money they have to buy food.
they must borrow against the next crop and
start out in debt.
Another food loss is harder to measure.
But it is real.
eat out the best parts of the grain.
These are the parts which contain
the vitamins and minerals which make grain the healthy food
it is. The
farmer may not see this loss.
But he should be told about it.
nutritious food can lead to sickness and more problems.
Seed for Planting
Part of the harvested grain is the seed for the
next crop. The
farmer must let the seeds rest
in a cool, dry place before he plants them.
Poor storage of seed grain means that some of
the seeds, or many of them, will not germinate
(grow) when they are planted.
If the seeds are
not stored well, the farmer will have to plant
many extra seeds to get enough plants.
seed grains that have not been stored well do
not grow well: they
may grow at different speeds.
This causes problems with cultivating and harvesting
Money to Fill Needs
A farmer usually must buy some of the tools and equipment he
home and farm use.
He may need to purchase corrugated metal sheets for
building, metal pots for cooking, metal tools for farming,
or cloth for
making clothes. To
get items which he cannot make himself, the farmer
has to offer money, or he has to barter.
Most farmers sell the grain they
do not use for food or seed to get money.
Or they trade the grain for
the things they need.
Because of poor drying and storage facilities, farmers
cannot keep their
grain safely for any period of time.
They are forced to sell the grain
soon after harvest.
The prices are low at this time because no one needs
grain. Everyone is
harvesting, and there is plenty of grain available.
Until the farmer can dry and store his grain safely, he is
not going to
grow much more than he needs for his family.
This lack of safe storage
means that total production of grain remains low.
Most farmers will not think in terms of country-wide
they will have in mind some things they would like to do if
more money. Good
grain storage can lead to more food, more money, better
seed, and a better future.
GRAIN IS A LIVING THING
Grain has certain characteristics which farmers must
understand if they
are to be able to dry and store their grain well.
Here are some of the
characteristics of grain which will be discussed:
Growth of seed grain.
Protection of the kernel by the seed coat.
Respiration (breathing) of grain kernels.
Moisture (water) in grain kernels.
Moisture movement between grain and air.
Farmers know a lot about planting and growing grain.
But most farmers
will not think about grain in all the ways listed
above. If they do
become aware of these characteristics of grain, the reasons
grain storage are going to make a lot more sense to
them. And farmers
are going to be able to do more toward solving their own
WHAT HAPPENS TO GRAIN IN STORAGE
Keeping grain safe in storage depends upon a number of
Moisture, temperature, insects, and molds, for example, all
changes in grain put into storage.
All factors which are most important
to good grain storage are presented in the following
some are discussed in greater detail in other places in the
REMEMBER: All of the
following points are related to one another.
Insects and their part in grain storage are the subject of
It is an important section.
Insects eat and ruin a lot of grain.
they grow inside the grain kernels, some insects are not
found in grain
until after they have done a lot of damage.
The section on insects will
give information on the major grain storage insects, on
where to look for
them, and on how to control them.
Insect activity, and the damage which results from this
closely related to temperature and moisture in stored
grain. It only take
a few insects in the right conditions -- for example, in
warm , moist
grain -- to make enough moisture and heat so that large
numbers of insects
can grow. More
insects will make more heat and water, and so on.
create the right conditions for the growth of molds.
Molds are very small plants.
They are so small they cannot be seen on
grain, but they are always there on the grain kernels.
In warm, moist
grain, they will germinate (grow) and produce threads called
hyphae. These hyphae
push through the seed coats of grain kernels and
attack the embryos of the grains.
Molds cause damage in a number of ways
They produce chemicals called enzymes which
can stop seeds
germinating and growing into new plants.
They decrease the quality of the grain for
food and for
Some molds produce chemicals which can
Farmers certainly are familiar with the sight and smell of
by mold. But they
are probably not aware of the conditions that lead to
molding, and they may not know what they can do to protect
from mold. Helpful
information and suggestions are presented later.
Moisture Content (Wetness)
Drying grain, and keeping it dry in storage, is the most
of good storage.
Many problems of grain storage are caused by moisture.
Both grain and air have moisture, and they act together in
ways that are
important to understand.
Therefore, a following section discusses
moisture content in grain and in the air; it also explains
in grain and moisture in the air are important to each
There are two temperatures which are important.
One is the outside
temperature of the air; the other is the temperature of the
air and grain
in the storage place.
It is easier to store grain in areas where the air
temperature is low or
never gets too hot.
In very cold weather, insects and molds do not grow
very quickly, or at all.
Seeds do not breathe as much.
In warm places, the grain is warm when it is put into
storage. Then, as
the outside temperatures go up, the temperature in stored
grain is likely
to get even higher.
When the temperature in the grain goes up, certain
things start happening:
Insects start growing and breeding.
Mold spores start multiplying.
Molds, insects, and grains all live and
water, and carbon dioxide to increase in
the stored grain.
Even in this brief look at temperature, it is easy to see
the need for
keeping grain cool and dry.
Keeping storage containers protected from
the hot sun is important.
Farmers who understand this fact have discovered
an important grain storage principle.
Rats and mice eat a lot of grain.
They can eat the whole kernels of
grain sorghum, wheat, and millet.
They chew on ears of maize.
Rodent damage is the easiest kind of
damage to see. Yet
farmers may not
realize how much damage rodents can
do; they may not be aware that rodents
spread diseases. Or
they may not know
what they can do to stop rodents from
eating their stored grain.
The section on rodents gives information
on the habits of rodents, the signs of rodents that a farmer
look for, and some ideas for keeping rodents out of stored
Clean Grain and Clean Storage Places
Farmers often do not realize how important it is to clean
the place for
storing grain. Even
grain that is healthy and whole when put into
storage can be damaged by insects or ruined by molds if
Farmers need to know that good grain storage requires
planning for a good
storage container or place, and careful handling and
cleaning of the grain.
Many farmers can improve the condition of
their stored grain simply by cleaning and
repairing their present grain storage
containers and buildings, and by putting
only healthy grain into storage.
manual helps spell out the necessary
steps for farmers who wish to improve,
(1) the quality of the grain they store,
and (2) the container into which they put
GOOD GRAIN STORAGE DEPENDS UPON BETTER DRYING AND BETTER
As mentioned before, drying is the key to storing grain
section on "Preparing Grain for Storage" covers
the importance of
careful harvesting, threshing, and moisture measurement
the grain into storage.
"Grain Dryer Models" presents plans for a
number of grain drying methods.
The manual section on storage
discusses methods already being
used by farmers, and gives ideas
for improving these methods.
the section provides plans and
construction procedures for a number
of grain bins. Each
storage methods is presented in
terms of its possible advantages
and disadvantages for use by farmers.
You will have to decide how to use the materials in this
farmers may be ready to make a mud silo; others require
good storage practices for storing grain in sacks.
One village may be
ready to make an oil barrel dryer.
Another village might like to try
solar dryers. These
are decisions which you and the farmers in your
area must make together.
The purpose here simply is to provide information
upon which good decisions can be made, and to provide some
in important grain storage areas.
The following leaflet provides an illustrated look at what
storage can do for farmers.
GOOD GRAIN STORAGE HELPS FARMERS
Suggested Uses: This
is a script which could be used to alert farmer
the need for improved storage. Choose
feel are most important and have them translated
and illustrated as necessary.
A good crop of grain means plenty of food.
Farmers work hard to grow their grain.
Grain is important.
A good crop means seed for planting the next
A good crop means you can buy things for
your family and
But you must have a good place to keep your
grain after the
You cannot use all the grain right away.
It is not good to sell grain right after
price for grain is lower at harvest time
available than at other times of the year.
You cannot eat all the grain.
You will want some later.
Seed grain must be stored safely until
A good grain storage place is a place to
keep grain safe
want to sell it, to eat it, or to plant it.
There are many ways to store grain.
Some farmers store
sacks. Some farmers store grain in clay
and in the
rafters of their homes. Some farmers
All grain storage places must protect the
mice, rats, and other pests.
Rats and mice enter open grain storage
They can eat
and spoil a lot of grain every day.
Birds and chickens like to eat grain too.
Many insects attack stored grain.
Insects get into grain very easily.
Some of them can fly,
begin eating the grain in the field before harvest.
Insects lay many eggs.
These insects eat and spoil a lot of
Insects, rats, and mice eat so much grain
that soon there is
less for you
to sell and eat.
Insects and rats put the droppings from their
bodies on the
they are eating. This makes the grain
make as much money when you sell this grain.
People get sick from eating grain which rats
Molds also attack stored grain.
Molds are tiny plants.
You cannot see these plants.
float in the air and need warmth and
grow. Mold plants usually are on stored
though you cannot see them.
Molds give grain a bad smell and change the
Molds like to grow in warm, wet storage
places, so you
grain cool and dry.
People can get sick if they eat grain with
mold on it.
It is important to keep insects, rats,
molds, and other
from your stored grain. Good grain
money and more food.
Your extension worker can help you with
grain storage problems.
He knows how
you can fight insects, rats
He will have ideas on ways you can improve
The following pictures show how one artist has chosen to
subject, "Good Grain Storage Helps Farmers."
As you can see, he has
chosen a certain number of important ideas from the scripts
highlighted them using pictures.
Perhaps these pictures will provide
you with ideas for illustrating your own leaflets.
GRAIN IS A LIVING THING
The Structure of Grain
Grain kernels are
living things. Grain which will be used
for seed must
be kept alive.
Living seeds also store better.
sorghum, wheat, millet, and so on, are all cereal grains
which belong to the
same grain family. As you know, these
grains do not
Maize is a large kernel with a triangular
shape; it has a
hard coat and a
large, oily germ which is easy to see on one end of the
Sorghum, on the other hand, is a round seed
in a brittle or
coat. The germ is very hard to see.
Although they look
different, the grains all share three basic parts:
the seed coat; the
endosperm; the embryo (germ).
The Seed Coat
Surrounds the embryo and the endosperm.
Protects the grain from attack by certain insects if
it is dry and un-cracked.
Cannot keep out molds and some insects.
which attack the embryo are most
dangerous because the
seed coat at the embryo is weak.
Takes up the largest part of the seed.
It is 80% of
the kernel volume in most grains.
Is the seed's food storage place.
It is mostly starch
Provides food for the developing seed when planted and
food for the seed in storage.
Provides food for farmers and others if the seed is not
Is the part of the seed which can develop into a new plant.
Contains most of the protein, fat, and vitamins of the
Is attacked easily by some insects and by molds.
grain which is attacked will not grow
into strong plants
or will not grow at all.
Food grains without embryos do
not provide as much nutrition as
grains with embryos.
GRAIN AND HOW THEY AFFECT STORAGE
Healthy grain can be
kept in storage longer than grain which is broken.
methods used by farmers often damage many of the grains.
If the grain is to
be threshed before it is stored, the threshing must
be done very
carefully. Careful handling of the
grains helps the grain
protect itself from
danger. Here are examples of ways in
grains are protected
by their structures:
The husks on maize ears protect the grain from
damage during harvesting
The husks on rice kernels protect that grain
from attack by most
A hard, dry seed coat with no cracks or splits in
it prevents molds and
insects from getting into
the kernel easily.
The endosperm of dry grain is hard and is not as
easily attacked by
Stored rice or wheat
or maize, etc., act in one way or another because
each has certain
characteristics which are affected by the ways it is
A farmer should know the characteristics of
grain he is storing.
Because there are
many kinds of grain, this manual can not talk a lot
Here it is most important to point out that
of the grain (the
way it is made) plays an important part in what does
or does not happen
to that grain in storage. The structure
of the grain
affects the length
of time the grain can be stored and the kind of
storage container it
should be put into. You may want to
for the farmers in
your area which talk directly about the structures
of the grains they
grow and which storage containers are best for their
Each kernel gets oxygen
from the air and
burns food from its
This process gives off heat and
dioxide. This process in grain
respiration. Respiration is faster
or slower depending
upon the temperature and moisture in the grain.
Respiration is slow
when grain is cool and dry. There is
respiration to keep
the embryo of the grain alive. This
process can continue
in storage for a
long time if the embryo is not attacked by mold,
insects, or high
temperatures. Slow respiration is important
Growth does not
happen at this low respiration level, but seed life
If the stored grain
has too much moisture or heat in it, the grain begins
faster. When seed grain is planted, for
example, it germinates
respiration has been speeded by water in the ground and the
warmth of the soil.
The way that grain,
moisture, and temperature work together is important
for farmers to
understand. Grain put into storage with
a lot of moisture
in it breathes much
faster than dry grain does. This moist
more heat and
creates conditions leading to mold growth and insect
The farmer who understands this will see the
need for storing
cool, dry grain.
Heat Producing and
Grain produces heat
during respiration. If
the grain is cool
and dry, it respires very
slowly and the
amount of heat it makes is
But if respiration gets faster
for some reason,
grain makes more and more
Spots of hot air form inside the storage
the stored grains hold the
outside the storage container does not have an immediate
effect on the grain
in large silos, but it can be a problem for the
farmer who has a
small metal storage bin which stands by his front door
and faces the sun
for some hours each day. The heat from
the sun warms
the bin, and this
warming spreads to the grain inside.
Any insects and
molds present in the
grain will grow much more quickly.
All harvested grain
holds a certain amount of
Most of the moisture is inside the
kernel; if the grain
is very wet, some of the
moisture is around
the outside of the kernel.
Farmers must dry the
grain until it only
holds about 12-13%
moisture if they are to
safely. Since moisture and drying are
so important, they are
discussed more fully
in another section.
Grain has other
characteristics, such as flow and pressure.
particularly important to a small-scale farmer.
needs to know what
the grain looks like inside and what there is about
grain that makes it
act in certain ways in storage.
GRAIN IS A LIVING THING
Select points as needed.
Translate and illustrate
them for distribution to
farmers in your area.
Each kernel of grain is a living thing.
Each grain is a
A seed can grow into a new plant just like the one it came
Most of the seed is food around a tiny part of the seed
called the embryo.
Some people call the embryo the germ
of the seed.
This embryo is the part of the seed that will grow into a
One part of the embryo will form the shoot that grows
above the ground.
The other part of the embryo will grow and become the
root of the plant.
This is the part of the plant that
grows under the ground.
There is a seed coat around the food and embryo.
protects the grain from being
hurt. Careful harvesting,
threshing, and storing will protect
the seed coat.
While they rest, seeds breathe and use the food that is
Seeds stay alive and are good for planting and selling if they
rest in places which are cool and dry.
A good grain storage place must be cool and dry.
It must protect
the grain from insects and other
Do not use high heat to dry the grain you are saving to plant
High heat will kill the embryo.
Store your seed grain separately from the grain you plan to
sell or to use for food.
Check the grain often. Make sure
it is dry. Do not let it
get too warm.
Make sure there are no insects in it.
it to see if molds are present.
Good storage of your seed crop means the next crop will be a
The living grain will grow into a new plant when
you put it into the earth.
GRAIN, MOISTURE, AND
WHAT MOISTURE IS
Moisture is water or
wetness. But moisture is a better word
to use when
talking about grain
storage. When farmers use the word
water, they are
likely to think of
lakes, rivers, wells, or containers of water.
think of water as a
liquid which is very easy to see and to measure.
A farmer may not be
familiar with the word moisture. Moisture
is a good
word because it can
describe something which is wet or contains water
wet. For example, the earth can have
moisture and not
A plant does not look wet, but when you
crush it, you will
(wetness) on your hand.
MOISTURE IN GRAIN
Each kernel of grain
has moisture inside. But the grain
not look wet when
you look at it. The farmer can tell if
it is wet by
cracking it between
his teeth. Wet grain is not hard
because the water
inside is wetting
the seed and keeping it soft, just like pouring water
on hard earth makes
the dirt soft. When the moisture leaves
during drying, the
grain becomes harder. The dryer the
grain, the harder
different amounts of water at different times:
the amount of
harvested grain depends mostly on the time of the harvest.
For example, grain
harvested in the rainy season may have more moisture
than grain harvested
in dry, sunny weather.
It is important to
note that some grains must contain more moisture than
harvested, if they are to be harvested safely.
This is true,
for instance, of new
varieties of rice. This rice must be
before it gets too
dry, or much of the rice will shatter or fall off the
Both maize and rice can be harvested when
the moisture content
in the kernels is in
the 20% range. However, maize can be
left in the
field to dry further
before harvesting. Rice must be
away and not be
allowed to dry in the field.
MOISTURE IN THE AIR
moisture also. Of course, the farmer
cannot see this kind
of wetness when he
looks at the air, because the moisture in the air is
in the form of
Just as grains hold
different amounts of water, air holds different
water. Warm air can hold more moisture
than cool air.
On a very hot day,
there can be a lot of moisture in the air, When
evening comes and
the temperature goes down, the air, now cooler,
cannot hold all the
moisture it held when it was warmer. So
extra moisture falls
out of the air and lands on the earth.
moisture from the
air is the dew seen in the cool early morning.
As the sun gets
higher during the day, the air temperature goes up.
The air, now warmer,
can hold more moisture. So the dew on
is taken up by the
Many farmers will
not be familiar with words such as relative humidity.
Nor do they really
have to be. It is not important to most
relative humidity is a percentage measurement of the
amount of moisture
actually in the air as compared to the maximum amount
of moisture that air
at that temperature could hold. Nor do
need to understand
that if the moisture content in the air remains the
same and the air
temperature goes up, the relative humidity goes down.
Relative humidity is
a meaningful phrase only to those who can measure
it and apply the
knowledge to drying times, etc.
Most farmers do not
have instruments which measure relative humidity.
But they have good
information if they understand two facts about air and
Warm air can hold more moisture than cold air.
Air at any temperature does not always hold as much
moisture as it possibly can.
The amount it actually
When air holds as much water as it
possibly can (100% relative
humidity), rain is likely.
HOW AIR, MOISTURE,
AND GRAIN INTERACT
Scientists say that
grain is hygroscopic because it loses or gains (adds)
moisture from the
air around it. At this point, it would
be easy to get
involved in a long
discussion of moisture and vapor pressure.
Since all things containing moisture have
and air have pressure.
Grain dries in the sun because
moisture vapor is moving from higher
pressure in the
wet grain to lower pressure in the air,
until the grain
and the air reach equilibrium vapor
This can be explained somewhat more
simply by saying that
two things containing water will push
that water back and
forth until a balance is reached.
The more moisture there
is, the harder the moisture can
push. That is, if there is
comparatively more moisture in the grain
than there is in
the air around the grain, the moisture in
the grain will
push out into the air.
The key to the drying process, then, is
placing grain in the
sun or in a drying machine so that the
kernels of grain can
be touched by warm moving air which has
less moisture in it
than the grain has.
The heat in the moving air will make the
moisture in the grain evaporate.
The moisture will become
water vapor and be absorbed and carried
away by the moving air.
It is useful for a
farmer to know that drying continues only as long as
the air around the
grain is able to absorb more moisture from the grain.
If the air contains
a lot of moisture, the grain is likely to take in that
moisture from the
air. The farmer should understand this
it explains the need
to keep dry grain away from moisture and/or air as
possible. Grain that is not sealed in a
closed container will
continue to exchange
moisture with the air. During the rainy
for example, grain
will take on moisture if left in an open container.
In the hot, dry
season, grain will lose the moisture again.
SAFE MOISTURE LEVELS
Grain put into
storage should not have more than a certain amount of
moisture inside its
kernels. Although the amount of
can hold in storage
safely can change, depending upon storage conditions,
moisture-safety percentages have been established.
The chart which
follows(*) shows that maize can be stored safely at 13.5%
moisture (that is,
13.5% of the total weight of the kernel can be
moisture), in air
which is 25-30 [degrees] C and has 70% relative humidity (that
is, the air at this
temperature can hold 30% more water than it is
At this point the kernel of maize and the
air are not going
to exchange moisture
back and forth. This is an equilibrium
This equilibrium is
the condition good grain storage tries to set up,
but it is very hard
to keep grain stored at conditions which keep
MOISTURE CONTENT FOR ONE
LESS) STORAGE AT 70%
RELATIVE HUMIDITY AND 27 [degrees] C
figures above are maximum recommended moisture levels.
should dry their grain as thoroughly as possible.
From "Handling and Storage of Food Grains in Tropical and
Areas," by D.W. Hall, published by
Food and Agriculture Organization of
the United Nations, 1970.
MOVEMENT OF MOISTURE
IN STORED GRAIN
Grain which is dry
and cool will keep for a long time if it is stored
However, there are a number of bad things
which can happen
to grain while it is
in storage. And moisture is a key part
of most of
the process of
deterioration (spoiling) that can occur in stored grain.
To discuss the role
of moisture in the storage container, it is necessary
to talk about:
insects, molds, and grain heating.
The farmer must
store only clean, healthy grain which has been dried
to safe storage
Broken grains and
pieces of straw or dirt increase the chances of storage
And, if the storage container does not keep
or insects, even
healthy, clean, dry grain can deteriorate.
is less likely to
happen if the grain starts in good condition.
There are two kinds
of temperature: temperature in the air
and temperature of the grain inside the storage container.
Some things to remember
Low temperature is better than high temperature for
Insects and molds do not grow at low
Grain breathes very slowly at low temperatures.
At low temperatures, little heat builds up inside the
grain from the living and breathing of
molds -- and the grain.
Rising temperatures outside the containers can increase
the temperature inside the container
-- particularly if
the container is not shaded or is made
Rising temperatures can lead to
insect and mold growth.
grain that looks clean, insects are
almost always there to some degree;
mold spores are present everywhere.
As the temperature of the grain goes
up, these insects and molds will
start to grow.
As the temperature goes up, molds and
insects grow faster.
The grain respires
If the grain contains
a lot of moisture, this process goes
Hot spots can form in areas of the grain where the most
mold and insect activity is
occurring. These hot spots
spread and cause great damage and loss
of the stored
The above points
show how temperature and moisture work together.
placed into storage should be as dry and cool as
Even then there can be a moisture problem
This problem often
is the result of a difference in temperature between
the inside and
outside of the storage container. When
cool air and
warm air mix in the
stored grain, the warm air cools and may be forced
moisture. This lost moisture becomes
water which can be seen
at the top and
bottom of the storage container. The
show what may happen
when there are differences in temperature between
the inside and
outside of the storage container:
These changes caused
by temperature can be seasonal, or they may be daily.
This depends upon
where the farmer lives. Obviously, it
is best to keep
stored grain at a
relatively constant temperature. The
will show various
ways of dealing with this problem.
Insects, Molds, and
Remember the dew and
how it forms because cold air and warm air cannot
hold the same amount
of moisture? This same thing is what
stored grain when
cold air and warm air meet each other because of
The farmer who understands dew will be able
understand how his
grain got caked and moldy even if it was dry when he
put it inside the
storage tin or container.
The pools of water
formed by the moisture forced out of the air make
the stored grain
wet. This wet grain begins to respire
at a faster and
If there are insect larvae and mold spores
begin to grow and
reproduce. Soon the insects, molds, and
grain all are
heat. This process produces the hot
spots spoken of earlier.
When the temperature
gets too high, insects will leave the heated spot
and go out into the
grain mass to find better living conditions.
trouble spots then
WHERE YOU ARE NOW
Now the background
for the subject of grain storage is complete.
you have been using
this manual with a farmer or group of farmers, they
now know what grain
is in a scientific way; the relationship among grain,
water, air, and
temperature; and some of the ways grain storage problems
In other words, they have some scientific
ideas about good
The next section deals with the subject of
storage. That discussion applies some
of the ideas from this
4 PREPARING GRAIN
discusses the steps a farmer should take to prepare grain
It gives these steps in the order he takes
them. Each of
these steps is
looked at here as an important part of the storage
Good harvesting, threshing, cleaning, and
drying practices are
important for the
success of any storage method a farmer may use.
Some grains, such as
new varieties of rice, should
be harvested when
they contain quite a bit of
Other types of grain, such as maize,
can be much drier
when harvested. But even when
the grain can be
allowed to dry in the field,
there is often too
much moisture in the air,
or even rain, and
the grain does not lose a lot
moisture. Therefore, for one reason or
another, the farmer
has to harvest very moist
Then he must somehow dry the grain to
If the grain is a
variety which can be allowed to
dry in the field,
and if the weather is good, the
farmer can let his
grain get as dry as possible
while it is still in
the field. In some dry, sunny
places, it is
possible to shock and windrow the
grain after cutting
it. Wheat, for example, is
tied in small
bundles that are stacked together
side by side.
Maize is also often stacked in
This practice allows the grain to dry
But this practice requires good weather.
And rodents, birds,
and insects can attack the grain
while it is drying.
Threshing is the
separating of grain kernels from stalks and husks.
usually cuts and threshes grain by hand.
method is used,
farmers must be careful to make sure all weeds and
straw are separated
from the harvested grain.
There are serious
problems in most hand-threshing methods, especially
grains. A common method uses trampling
or beating of the grain
to free the
kernels. This method often causes
cracking of the grain.
In addition, unless
threshing is carefully done, much of the grain is
thrown away with the
No matter what
method the farmer uses for harvesting and threshing, he
should aim for
clean, whole grain. There are machines
can harvest and
thresh grain at the same time. Most
cannot afford these
machines. And for the small farmer,
it is easier to separate weeds from the
and less grain is
lost during the harvest.
Clean grain keeps in
storage much better than dirty grain.
grain often contains
small amounts of straw, weed seeds, and dirt.
decrease the value of the crop if they remain in the
They also cause the grain to deteriorate
during storage. Dirt
holds moisture, insects,
and molds. Dirt also keeps air from
grain. Dirty grain heats more and
deteriorates more quickly
than clean grain
Insects also must be
removed from the grain. Those which eat
cause damage in
several ways. They destroy much of the
grain by eating
As they grow and multiply, insects produce
heat which can cause
grain to spoil more
rapidly. Grain with a lot of insects in
a much lower price
than clean grain does.
harvesting machines get grain pretty clean.
blow air through the
grain: this removes very light
materials such as
chaff, husks, and
dust. The grain then is sieved.
The pieces smaller
than the grain
kernels are removed by passing them over a fine mesh
The larger pieces of waste are passed over a
screen that has a
mesh size larger
than the kernels.
technique can be used even when a machine is not available.
However, it requires
screens of proper mesh size. When
screens are not
available, or when a
substitute cannot be found for them, there are other,
One of the simplest
grain cleaning uses
this method is
The grain is thrown
upward in the
As it falls, the lighter
pieces -- dust,
grain -- are blown
aside by the
But the heavier stones and
pieces of earth fall
with the grain.
For good cleaning,
winnowing must be
done over and
over. Some grain is
always lost, and so
the method wastes
Some farmers place this
waste material where
take the lost grain
Farmers also should
clean their grain each time they move it to a new
If this cleaning is not done, dirty grain
from one place
may be mixed with
clean grain from another. Even grain
that has been
cleaned quite well
before may need cleaning again. Insects
do not need
a long time to get
into grain. Both the insects and their
dirt should be
removed before the
grain is added to grain already in the storage areas.
The farmer should
remember that cleaning is important because:
dirty grain deteriorates more rapidly in storage.
clean grain does not heat as quickly.
insects breed faster in dirty grain.
THE NEED FOR DRYING
If moist grain is
stored without air moving through it, the grain becomes
The grain respires more quickly and gives
off more heat and moisture.
The grain can be
damaged if the heat is too great.
Heat builds up more quickly in wet grain.
Molds form rapidly.
Insects multiply faster.
Grain can germinate (sprout) while still in storage.
It has long been
known that meat, fish, and fruit can be preserved by
Dried fish and fruit are widely used for food.
do not deteriorate
much even when stored for long times.
This is because
usually occur very slowly when there is little moisture.
This is true for
grain. Well-dried grain deteriorates
only slowly even
at fairly high temperatures.
HOW DRYING HAPPENS
In the Field
In order to dry
grain, moisture in and on its kernels must be carried
As the grain stands in the field, the dry
air moving past it takes
up moisture from the
grain. This air, now moist, is then blown
from the grain by
The drying process
is most rapid if the air does not contain much moisture
and if there is a
wind. Little drying of the grain occurs
if the air
contains a lot of
moisture, or if there is not much wind.
Hot air passing
grain usually dries
more quickly than
From the previous
section, it is easy
that there are three
reasons for this:
Hot air can hold more water than an equal amount of cold
When dry air blows through the grain, the hotter
the air, the more water it can carry
away from the grain.
Water evaporates more quickly when it is warm.
blowing past grain warms the moisture
on the surface of
This moisture leaves the grain more quickly.
Hot air heats the grain itself.
Moisture deep inside
the kernel moves through the kernel
faster at high
It moves to the surface of the kernel
When this moisture reaches the surface,
it leaves the grain and is taken up as
vapor by the
The above facts also
apply to drying grain after it is harvested.
must pass through
the grain to dry it. Moisture between
and on their
surfaces is carried away first. The
moisture deep within
the kernels must
first come to the outside of the kernel.
can it be removed by
the flow of air. Air must be moving for
Only if new, dry air enters the grain can
the moist air
between the kernels
be replaced by air which can take up more water
This is the principle behind some drying
force cool dry air
or warm dry air through the grain to speed drying.
Grain drying methods
and models are presented in the next section.
It is nearly
impossible to dry any grain completely.
The last ten
percent or so of
moisture in the kernel is tightly held by the kernel.
It can be removed
only with great difficulty. Luckily,
grain stores well
with this amount of
water in it. In some cases, removal of
water harms the
Whatever method a
farmer uses to dry his grain, he must be careful not
to let the
temperature in the drying grain get too high.
Too high a
the kernels of some grains to burst.
which are too high
(when drying maize and rice) cause breaking, cracking,
and discoloration of
the kernels. This leads to a decrease
yield and protein
quality. Maize which is used for oil
Grain used for
baking and milling can be dried at temperatures higher
than grain to be
used for seed. Grain used for seed
should not be
heated above 40-45
[degrees] C. High temperatures can kill
the seed embryo, and
the seed will not
germinate when planted.
The following are
the highest safe temperatures for drying grain.
MAXIMUM TEMPERATURE, [degrees] C
Food for Humans, except rice and
Milling for Flour
Rice for Food
Beans for Food
The drying temperature depends upon the use
of the grain.
Drying at lower,
rather than highest, temperatures usually gives a better
grain. Also, as a rough rule, lower
temperatures should be
used for very moist
grain than for dryer grain. It is
better to take a
longer time, and use
a lower heat, to dry moist grain than it is to run the
risk of parching or
burning the grain.
TESTING GRAIN FOR
Grain that is too
moist will heat in storage. All stored
frequently to see if it is heating.
Heat build-up deep
within the grain is
a serious danger signal. Unfortunately,
until you can feel
the heat in the grain is waiting too long.
moisture testing devices are sold. They
available when and
where they are needed. Most of them are
An appendix to this manual contains a
meters. This will show you the kinds of
meters which are
Extension workers should know
grain moisture percentages are
in the following way:
PERCENT MOISTURE =
weight of completely dry grain
total weight of
There are several ways to
measure the amount of
moisture in grain in order to
make this mathematical
Unfortunately none of these
are very simple or inexpensive.
experienced farmer can usually
tell if grain is dry
enough for storage. The
method used by the
farmer varies from region
to region and
depends upon the type of grain.
However, two methods
used by experienced
farmers in many
places are: (1) pressing the
kernel of grain with
the thumb nail to see how
hard it is (dry
grain is hard to press), and (2) crushing the grain
kernel between the
teeth to make sure it is hard enough (dry enough)
Some people talk of testing to see if grain
is dry enough
by smelling it for an
"off" smell or by rattling grain kernels in a tin
can to hear if the
dull sound of wet grain has given way to a sharper
sound of dry grain.
The scope of this
first manual edition can not be broad enough to allow
us to add specific
drying instructions and suggestions for each type
Future editions may be able to do this.
If your area is
more involved with
wheat, and you feel there are additional facts farmers
should know, or
there are drying methods you have found particularly
helpful and would
like to share with others around the world, send
If there are plans
for threshers and winnowers which could be made and
used effectively by
others, these also could be included in future
editions of this
PREPARING GRAIN FOR STORAGE
A shortened version of the text.
This could easily
be illustrated and translated
for use by farmers.
Check the grain in the field before you harvest.
sure the grain is free of insects and
Clean old dirt and grain from harvesting tools.
Remove old grain and dirt from carts or anything
used to carry the grain from the field
Use insecticide on all bins, sacks, and equipment.
Remember to ask your extension worker
Always use insecticide carefully.
Harvest the grain carefully. Do
not break the grains.
Broken grain will not store well.
Keep the grain cool and dry between the time you
harvest and the time you store it.
Clean the grain carefully.
Insects and molds like
to live in harvested grain.
Sift, screen, winnow, or pick out by hand all dirt,
straw, chaff, broken pieces of grain,
These materials hold water. The
grain dries better
and faster after all the dirt is
Good drying is very important.
Insects and molds
like moist grain. Dry
grain is harder for them to
Some farmers dry grain in the field.
and birds can attack this grain
easily. Also, this
grain can get wet if it rains.
Maize can be dried
better in the field if the stalk is broken, and the
ear hangs upside down.
It is better to take the grain out of the field.
You can bring the grain to a special
and dry it in the sun.
Keep the grain off the ground while it is drying.
Grain picks up moisture from the
Spread the grain on mats or flat boards to dry in
Some farmers spread the grain on large trays.
trays are put out when the sun is
trays are placed under a roof when it
Insects will leave grain that is in the sun.
do not like hot sunlight.
You must watch the drying grain to protect it from
rodents and birds.
Some farmers like to use open storage places called
These cribs have roofs on them, and they are
built on legs.
These cribs work well for unshelled maize (maize that
has not been removed from the cob, or
inner part of
the ear) or for unthreshed millet,
sorghum, or rice.
Maize can dry in the crib until it is
dry enough for
Some farmers build large drying machines to dry their
* The grain is put in the
dryer. A fire is lit under
the grain to warm and dry the grain.
Artificial or mechanical dryers can be used by groups
of farmers to dry their grain.
Your extension worker
can tell you about these dryers.
Test the grain when you think it is dry.
must be very dry before you put it in
Dry grain is hard. It is hard to
break it with your
Extension workers sometimes use special tools to see
if the grain is dry.
These tools are called moisture
When the grain is dry, look for insects again.
the grain over with your hand.
You can see insects
Sift out the insects. Or spread
the grain in the sun.
Destroy the insects you take out of grain.
They will go right back into the grain
if you do not
Put the grain into storage containers before insects
can get into it again.
Put each kind of grain into a separate container.
Do not put new grain with old grain.
Store new grain
Use old grain first.
Store rice with the outer coat on.
This coat helps
protect the grain from insects and
mold. The grain
will be good for a longer time.
5 GRAIN DRYER MODELS
This manual already
has talked about the need for drying of the grain.
rice, millet, or sorghum often is stored in cribs for
The ears, or heads, do not pack
tightly. Because the
cribs are open to
the wind, air moves through the stored grain and dries
Even so, storage in cribs is more effective
in the dry season. The
more humid air of
the wet season may actually add moisture to the grain.
In addition, insects
and rodents can cause serious damage to unprotected
grain stored in
cribs for long periods.
particularly those with small kernels like millet, dry
very slowly during
storage. The kernels pack tightly
together. As a result,
air cannot move
easily through the grain. Such grains
can be spread
in thin layers in
the sun for drying. If possible, the
grain should be on
a screen to let air
enter the bottom. The grain should be
carefully. The grain kernels can crack
if they are stirred too
The newer drying
here use heated air
to dry the grain.
Hot, dry air is
blown through the
These methods dry the grain
well. Most of them require
the burning of fuel
to heat the
This fact, together with
the cost of building
often limits the
drying machines for
<THE PIT OIL
A farmer has to
think about a lot of things before he can decide which type
of drying method to
use for his crop. Here are some of the
he must keep in
Does his present method work? If
it does, why change it? If
it does not work, why not?
How much money will he have to spend for a new drying method?
Would he be able to maintain a new drying machine?
Does he have enough time to operate it?
Would the cost of the dryer be easy for him to get back because
of better storage leading to more
grain to sell?
Would it be better to join a group of farmers and pay for the
cost of a dryer with a group?
Or does the farmer dry enough
grain to make use of a dryer by
You will probably be
able to help by offering alternatives.
For many farmers,
an improved method
of crib drying for maize or sun drying for smaller,
would be a step easily taken. Such a
step would insure
a much better crop.
Here are some ideas
for sun-drying grain:
Spread the grain in thin layers on trays which can be carried.
Stack the trays under sheds or roofs
at night to protect the
grain from dew or from rain.
Make trays with fine-mesh screening for the bottom.
the trays so they do not rest on the
ground. The screening
lets dust and straw fall out of the
grain. Put the trays on
top of each other under roofs or sheds
at night and when it
SUN DRYING USING
Find a plastic sheet. Or use
several plastic sheets joined
You need a sheet about 10m x 3m.
The plastic should
be at least .004 gauge thick.
Build a mound of hard-packed earth to place the plastic on.
If you use level ground, build a dike
of earth around the area
on which the plastic will be placed to
protect the drying
grain from water.
Make sure there are no rocks, wood and sharp things on the
ground where the plastic will go.
The plastic tears easily.
Place the plastic in the prepared place.
Attach the narrow end of the plastic to straight poles made from
bamboo or other smooth material.
Put clean grain on the plastic.
Do not make the grain more than
Stir often so the grain will dry faster.
Turning and stirring
makes sure all parts of the grain are
touched by air and sun.
The rake or other tool used to stir the grain must have smooth,
This tool then will not damage the plastic
As the grain dries, moisture from the grain collects on the
After the grain has been drying for two hours, push all
the grain to one half of the plastic.
Let this plastic dry for 5 minutes or so.
Push all the grain to the other half of the plastic that is now
and let this half dry for 5 minutes.
The plastic sheet should be aired in this way every two hours while
drying is going on.
Cover the grain at night. Push
all the grain to one end and fold
the plastic over as a cover.
Or place an extra piece of plastic over the grain.
Remember to put soil, boards, rocks, and heavy things on the corners
and edges of the plastic cover to keep
it from blowing off.
THE IMPROVED MAIZE DRYING AND
Maize holds a great
deal of moisture inside its kernels and husk.
maize is harvested,
the moisture content is high. It must
be much drier
before it can be put
into closed storage containers. If
maize is put into
a closed container
right after harvest, molds cause heavy losses of grain.
Harvested maize must
have air passing around it to dry the kernels.
the kernels are
dryer, they can be shelled (taken off the cob) and stored
containers. To dry maize before
shelling, some farmers keep
the husks on the
ears. Then they tie the husks into
bunches and hang these
trees. Some farmers hang these bunches
on poles set into the
ground or put them
in the roofs of cooking or living shelters.
remove the husks and pile the ears loosely in open-weave
basket granaries or
in covered crib granaries. These
protect the grain from
rain. Storing maize this way allows air
over the grain and
dry it better. This way of storing the
maize while it
is drying helps
protect the maize from mold.
But insects remain a
big problem. They can attack maize
drying in cribs
Many farmers choose to leave the husk on the
maize. This does
protection from insect attack -- particularly in traditional
varieties of maize
where the husk is tight and fits closely over the ear.
In newer, hybrid
varieties of maize, the husk is smaller and the ear is
These varieties are more easily attacked by
insects. Maize with
the husks left on
will take longer to dry because the air cannot pass
freely over the
ear. Also, the husks are full of
moisture -- increasing
drying time and the
risk of molding.
So, a good way to
dry and store maize would:
allow the maize to dry without the husks.
control insect attack at the same time.
already done in many countries, seemed a good method needing
improvement. Therefore, much work and
study were done to
into crib storage to allow for both faster drying and
effective use of
insecticides. Much of the improvement
in the crib storage
method is based on
proper use of insecticides.
Insect Control in
To reduce losses due
to insects, a number of insecticides have been
tested for open crib
storage. The maize put into the crib
must have the
husks removed so
that the insecticide can cover the whole surface of the
insecticide to the maize ears in layers.
Put down a layer of
deep. Dust the layer with
insecticide. Put down another
layer of ears, and
then more insecticide. Continue until
the crib is full
When the crib is
full, put insecticide on the outside walls of the crib
to prevent insects
The wind, rain, and
sun all can affect how long the insecticide lasts.
You can put more
insecticide on the outside of the crib every three to
Look at the maize in the crib every few
weeks to see if the
insecticide is still
working. The insecticide put inside the
last only four or
five months. But while it is working it
can reduce the
amount of maize
damaged by insect attack.
After four months,
check the grain moisture level. The
maize may be dry
enough to shell and
store in sacks or bins. The maize is
dry when the
sharply between your teeth and are not soft.
If the grain
is not dry enough,
remove all the maize and put it back into the crib
again, layer by
layer, dusting with insecticide as you go.
Keep the crib no
wider than 1m. Between 60 and 100cm are
good widths for
cribs. The narrow width helps maize to
dry more quickly.
Air cannot move
through wider cribs to cool the grain in the middle.
grain in a wider
crib will heat, and be attacked by mold and insects.
Rain which wets the
grain through open crib walls is not generally a problem.
Only the surface of
the maize on the sides gets wet, and this dries
quickly after the
rain stops. This rain causes no
increase in moisture
content of the grain
if there is sunny weather afterwards.
The following plan
is a modification of a crib designed and tested by
the Nigerian Stored
Products Research Institute and the FAO Rural
Storage Center at
IITA, Ibadan, Nigeria. The plan is for
a 2m long
It stores 800kg of maize ears (this will
give 540 kg of shelled
A crib which is 1,50m high, 0 60m wide and
1m long will store
400kg of maize ears
(yields 270kg of shelled maize).
Some General Remarks
About The Improved Maize Drying and Storage Crib
Use materials that are easy to find in your local area.
The crib will work best if it is no wider than 60-70cm.
A good height for the crib is 2,00-2,25m from the ground to
There is at least 50-75cm between the bottom of the
crib and the ground.
Most rats cannot jump this high.
If bamboo in your area is attacked by insect borers, use
another local wood for the
legs. Make sure the wood is termite
These legs must have rat guards put on them.
The long sides of the crib must face the sun.
That is, they
should face the east and west.
The short sides will then face
north and south.
Make the crib larger by adding more sections.
Make it longer.
Do not make it wider.
Tools and Materials
This is a
guide. You can use what you have
available. The frame is
If bamboo is not available in your area, or
if the bamboo in
your area is
attacked by insect pests, use wood that is resistant to
termites or any
other pests. Lash it together the same
way you would
For the building
frame (all bamboo or substitute):
3 vertical supports, 3.5m long, with V-notches and lashing
slots in one end of each one
3 vertical supports, 3m long, with V-notches and lashing slots
in one end of each one
2 horizontal roof supports, 2.5m long
2 horizontal platform (floor) supports, 2
6 vertical platform supports (with V-notches in one end of each),
6 notched horizontal width spacers, 70cm long
25 poles, 95cm long, for the platform surface
For the wall bracing
and covering (raffia, small bamboo or other wood):
8 cross braces (optional if frame is very strong):
* 4 must be about 2.5m long
* 4 must be about 1.70M long
8 wall supports, 2.25m long
8 wall supports, 1m long
raffia or other strong slats for the wall covering.
together into a mat.
The finished mat should be about 6m long
For the roof (all
bamboo or substitute, except for purlins, and roof
covering and loading
2 horizontal pieces, 3.25M long
3 cross pieces, 1m long
2 angle braces, 1m long
7 purlins, 3.25m long. Six of
these will be lashed across
the cross pieces to support the roof
covering; one may be
attached to the front loading cover.
raffia mat or grass for thatch to cover the roof, and also for
the front loading cover.
You will need a horizontal piece at
least 2.25m long to weave the
loading cover material onto -- it
need not be bamboo or of a large
For rat guards (if
you need them):
See Section 6, Part 2 of this manual
for directions on making
rat guards (baffles).
For the lashing
You will need plenty of rattan, rope or tie vine for lashing
all the wood pieces together.
Select a site.
Find a good site for your storage crib.
Keep the crib away
from the fields.
This stops insects from flying to the drying
grain from the fields.
Prepare your materials.
Collect all the materials you will need.
Make V-shaped notches in one end of each
of the three 3.5m vertical supports
and cut some grooves on each side just
beneath the notches to provide a hold
the lashing there.
Do the same on one end
of each of the three 3m vertical
Make V-shaped notches in one end of
each of the six 1.5m vertical
support posts (e).
Make holes all the way through
each end of all six 70cm
horizontal spacers (f).
Organize all the pieces, or mark them with the appropriate
letters, so you can find them quickly
Make holes in the ground for the legs.
Mark spots for holes for the vertical supports (legs)(a) and
(b) on the ground.
Make a mark for the first hole; measure
1m and make another mark.
Measure 1m from that mark in the
same direction and make a third
mark. You should now have
3 marks in a straight line.
Each mark will be the center of
Make three more marks, each 1m apart, in a line parallel to
the first line and 75cm away.
Each of the three new marks
should be directly opposite one of the
first marks and 75cm
Dig six holes, each centered on one of the marks.
holes 50cm deep and wide enough so
that two vertical supports
will fit down into each one.
Erect the vertical supports.
Lay the three 3.5m vertical
supports (a) on the ground
1m apart, with their ends
Lash one of the
2.5m horizontal roof supports
(c) to the notched ends.
Lay the three 3m vertical
supports (b) on the ground
in the same way and lash
the other horizontal roof
support (c) to the notched
Place the two assemblies
into the holes.
Erect the vertical platform supports.
Place the vertical platform
supports (e) into the holes
on the insides of the vertical
supports you have
placed in the holes.
sure the V-notches are
Tie the platform supports to
the longer supports temporarily
until the next step is
Install the platform support framework and
make the structure
Place the two horizontal
platform supports (d) in the
V-notches of the platform
Lash three of the notched
horizontal spacers (f) to the
vertical supports (a) and (b),
across the width of the crib.
Level and square the framework.
Fill the holes around the
vertical supports with small
stones and soil.
Lash all joints tightly.
Finish the platform.
Lash the twenty-five
95cm poles (g) next
to each other on the
Install the cross braces.
If you think the frame is not
sturdy enough by itself, lash
the cross braces (h) loosely
to the vertical supports on
the outside of the crib.
The 2 1/2m cross braces are
paired on the long sides of
the crib, and the 1,70m cross
braces are paired on the
ends of the crib.
Each brace should extend from
somewhere near a top corner
to somewhere near the opposite
room for a loading cover on
the higher side of the crib.
Make sure the frame is straight
Lash the braces
Install the wall supports and wall covering.
Lash four of the 2.25m wall
supports (i) to the vertical
supports along the inside of
one of the long sides of the
Lash the remaining four
supports to the inside of the
other long side of the crib.
Lash four of the 1m wall supports
(j) to the vertical
supports along the inside of
one end of the crib, and four
of them along the inside of
the other end.
Lash the already-prepared wall
covering, 6m x 1.5m (k), to
all the wall supports on the
inside of the frame.
Build the roof.
Call the high side of the crib
the front and the lower side
Measure the distance between the
centerlines of the front and the
back horizontal roof supports (c)
which are lashed to the tops of
the vertical supports (a) and (b).
Lay out the two 3.25m horizontal
roof pieces (l) on the ground so
their centerlines are the same
distance apart as the measurement
you have just made.
Lash the three 1m cross pieces
(m) on top of the horizontal
roof pieces, 1m apart.
roof is placed on top of the frame, the
cross pieces should cross over
the ends of the vertical supports of the
Lash the two 1m angle braces (n) to the
horizontal roof members so
that they extend diagonally across the two
spaces in the roof frame.
Lash six 3.25m purlins (o) on top of the
three cross braces so that
they extend longways along the roof
frame. Lash the first and last
purlins near the ends of the roof cross
Lash raffia mat in overlapping layers to the
Install the roof.
Place the roof on top of
the frame as shown
(looking at the end).
Lash the roof in place.
Make and install a
front loafing cover.
Lash raffia mat to a 2.25m
long bar to form the front
The mat should
be made large enough to hang
down beyond the top edge of
the wall covering when the bar
is lashed in place up under
the front edge of the roof.
Lash the bar holding the raffia mat up under
the front horizontal
The crib is ready for use.
Load the crib.
Lash down the bottom corners of the loading cover
to the frame during drying and storage.
NEWER DRYING METHODS
Some farmers have
more money and are more in
need of a faster,
more reliable way of drying
Controlled drying, or drying
with a device which
creates heated air for
drying, can be very
helpful to farmers who are
ready and able to
make use of newer methods.
these drying methods can
help a farmer to:
* harvest earlier and get his
ready for a new crop sooner.
avoid grain losses to insects,
birds, and rodents during long
natural drying times.
store better-prepared grain, keep it in storage longer, and
take it out in better condition.
make more money from the sale of his grain.
Four different dryer
plans are presented here. Two are made
barrels and are
heated with a fire. The Philippines
Rice Dryer uses a
fan and also uses
heated air. The solar dryers are three
the same idea.
Be Sure a Dryer Will
Suit Farmers' Needs
There are several
factors which may determine the usefulness of faster
drying to farmers in
your area. It is not possible to give
for what a farmer
could do in every case, but these are some of the basic
Method. It will not be as useful to
build a dryer that dries
grain to a low
moisture level, and then store the grain in something
which will not keep
it this dry -- such as cribs, unsealed gourds or
baskets, sacks, most
kinds of earthen pits, or mud-walled structures
which do not have
extra protection against moisture.
will make the use of
these dryers worthwhile.
Type and Condition
of Grain. Rice will crack easily in
Newer varieties of rice must be harvested
when they still contain
around 25% moisture;
since the husks (containing moisture themselves)
must be left on
while drying, and the rice grains will be tightly packed,
a very long time in
the dryer would be needed. In the two
oil barrel dryer
designs, heat is not
likely to flow evenly through the tightly packed
and much rice would
be damaged by
fans are added to
barrel dryers to
force a more
even flow of warm
air up through
the grain, farmers
should be able
to dry rice
Dryer uses this
It may be difficult or
impossible to dry
rice in solar
Other grains which also
pack tightly, but
give up their
easily, and are not
so likely to crack
may be safely dried
as long as
not too thick a
layer is put
into the dryer at
Grain. Drying very moist grain will
take longer. The safest
way to dry moist
grain is for a longer time at a lower temperature.
would be difficult
to avoid overheating portions of the drying grain
during a long period
of time if the temperature were not kept down.
It is difficult to
control the drying temperatures accurately in oil
without fans and in solar dryers.
Air. The weather in your area will
affect how long the
grain takes to dry. In a
wet, cold climate or
season, grain will take
longer to dry than
in a dry, warm place.
might be very useful
where drying must be
done in wet or cold
cause farmers to lose
grain to insects and
long natural drying
at least in the
cases of the
oil barrel and solar
this must be weighed
problems caused by
long drying times in
What kinds of fuel are available, and how
does it cost?
You must know this to determine the
value of heated
drying, especially if you expect longer
drying times in a
dryer. Firewood is not always
plentiful -- or even
available -- in an area. Even if
available, it may be
costly. Maize cobs or some other
natural fuel may be
available. Farmers may have to
pay the labor costs
for gathering these fuels. Try
to be sure farmers
will not be spending more on fuel
than they will be
saving by marketing more and better
Factors. If the grain is to be used to
seed, it should
not be heated beyond
45 [degrees] C. It will be difficult or
impossible to control
the drying of seed
grain in these dryers.
costs, the availability of some materials, and
cultural values or
local preferences must also be taken into account.
Some Notes on the
There are many
dryers being developed all over the world.
But much of
this research is
being carried out for use in large-scale drying operations.
This manual is
concerned with the small-scale farmer and his problems.
The drying method he
chooses must be appropriate for his situation.
The two dryers made
out of oil barrels and hand-rammed earth or mudblocks
have only one part
which may be expensive -- the oil barrels themselves --,
but the materials
are available almost everywhere. In the
Pit Oil Barrel
Dryer the barrels
are sunk into a pit. The Simple Oil
Barrel Dryer is
built entirely above
ground. They each require mostly simple
would be good
projects for a group of farmers.
<CUTAWAY OF THE
PIT OIL BARREL DRYER>
The Philippines Rice
Dryer is made from wood and spare auto parts.
A fan provides
reliable air flow and more even heating.
or rice hulls may be
used for heating fuel, and a small gasoline or
diesel engine, or an
electric motor may be used to power the fan.
requires more in the
way of materials. Thus it may not be
many farmers because
of unavailability or high cost of materials.
the plan is included
because there are farmers who are interested in
this kind of
machine, and it does represent a relatively small-scale,
The solar dryers
faster drying and
By enclosing the drying
grain, they retain
of the sun better
spreading the grain
the sun to dry.
little or no
Except possibly for
sheet or corrugated
all the materials
One of the models'
capacity can be
by adding a fire and
under the grain bed.
<A MODIFIED SOLAR
Again it is
important to say that these dryers and drying methods are
included here to
provide good examples of drying choices farmers might
in. If a method is not quite right for
the farmers in
your area, perhaps
only a slight change will be necessary.
discover you can use
ideas from one plan in another plan.
Let us know
if VITA can help
make one of these plans more useful. If
you know of
a plan for a
small-scale dryer useful to farmers which is not included
here, send it to
VITA for inclusion in the manual.
<A SIMPLE OIL
A SIMPLE OIL BARREL DRYER
This design is based
on material prepared in 1973 by the Institute for
Research at the Ahmadu Bello University in Zaria, Nigeria.
It is similar to the
Pit Oil Barrel Dryer, but it is easier to build.
It rests on the
ground so you do not need to dig any pits or trenches.
The drying grain is
placed on a screen floor above four oil barrels
together. Warm air from the fire --
which is built in the front
half of the barrel
chamber -- passes through the barrels and out the
This warms the air around the barrels, which
rises through the
screen floor and
dries the grain.
Grain can be
harvested without waiting for any drying in the field and
during any weather
(if you build a shelter over the dryer).
insect and rodent
damage during drying in fields or cribs are avoided.
materials are easy to find in most places.
It is better for a
group of farmers to share in the building and use of
Make sure there is enough fuel in your area
to operate the
Firewood or maize cobs will work well.
Placing a fan to force
air through the
barrels will reduce the amount of fuel needed.
DO NOT USE THIS
DRYER TO DRY GRAIN KERNELS YOU WILL USE LATER FOR PLANTING.
IT GETS TOO HOT.
In this plan
mudblocks are used to make the walls.
Hand-rammed earth may
also be used without
putting it into blocks first. You may
material that will be as strong and resistant to wear and
heat, such as burned
brick. Sandcrete (cement and sand) or
will crack with the
heat. If banco (earth and water) is
already used for
construction in your
area, the same high-clay-content soil will work well
for the dryer.
You may mix in cement with low-clay soil to
This dryer is made
with four barrels. You can build one
with more or less
If you make it too much longer you may have
trouble getting a
good draft from the
fire going through them. You should
also narrow the
width of the dryer
somewhat if it is longer, so as not to overload its
capacity. You can make a shorter dryer
wider. A smaller dryer
might also be very
useful to dry smaller fruit or vegetable crops.
INSTRUCTIONS THROUGH BEFORE YOU BEGIN
Tools and Materials
4 220-litre oil barrels
about 375 mudblocks, each measuring 15 x 20 x 25cm
* wood to make a form for
about 2m of heavy wire, to join the barrels
3 strips of small-mesh screen, each about 180cm long
and a few centimeters wide, to
cover joints between barrels
a little cement and some sand to make mortar for sealing the
joints between the barrels
13 6-10cm wide logs for drying floor supports.
Cut them about
2m long, equal to the outside
width of the dryer.
6.5 or 7 square meters wire mesh, for the drying floor
about the same area of heavy
woven mats, plus a total of 10m
of wire mesh strips about 20cm
materials for making concrete, plus
or heavy metal bars.
These will make reinforcing crosspieces
across the barrels in the front
and back walls of the dryer.
Select and prepare a site.
Select a site that is well drained and can easily be made level.
Plan to place the dryer so the chimney will be on the downwind
side of the prevailing wind during
the season when the dryer
will be used most.
Build up the ground on the site a little so rainwater will not
collect around the dryer.
Make it level.
Make the raised and
level area about 6,50m x 4m.
Tamp the earth down firmly so it will not shift or crumble
under the finished dryer.
Assemble the oil drums.
Cut both ends from three 220 litre barrels.
Cut one end from a
hole about 20 x 20cm
across near the edge in the
other end of this barrel.
will make an opening into the
Punch four evenly spaced holes
around the rim of each barrel
where it will join another
Join the four barrels together
by tying pieces of heavy wire
through the punched holes.
Twist the ends and press them
down flat against the barrel.
Save two of the cut-off barrel
ends to use later as dampers,
one at the front entrance to
the barrels and part of the
other over top of the chimney
Make a form out of
wood to mold mudblocks
that will make
three at a time
might be a good
Make it so
that each finished
block will measure
15 x 20 x 25cm.
You will need about
Let them dry
hard before using.
Begin the dryer walls.
Mark the outside dimensions of the dryer on the dirt foundation
you have made.
It will be a rectangle measuring about 3,50
Call 3,50m the length of the sides and 2m the width across the
front and the back.
Make your marks so that the front of the
dryer will sit back about 2m from
the edge of the raised and
levelled earth foundation.
This will leave about 1m at the back.
Leave about 1m on each side.
Allow for variations in the actual size because of differences
in the mudblocks and spaces between
them for mortar.
Make a mixture of mortar out of the same material you used for the
Add just enough water so it is not too watery.
Lay down the first layer of mudblocks.
Place blocks so that 20cm
is the thickness of the walls and
15cm is the vertical dimension.
Mortar between the blocks. Allow
about lcm between blocks for a
good mortar joint.
It is important to make the right distance between the front and
the back walls.
Since the assembled oil barrels will be
3,45m long, make the distance
between the inside edges of the front
and back walls about 3,10m.
This will allow the ends of the barrels
to rest firmly on the first layer
of blocks at each end. Later
they will be enclosed around the
sides by the finished end walls,
making a good seal against smoke
from the fire leaking around the
barrels and passing up through the
The three spaces along each side wall will be air vents.
dryer is in operation cool air will
be drawn in through them,
warmed, and then rise through the
grain to dry it.
Make the air vents each about 15cm across.
If you have trouble
getting a 3,10m distance between
the inside edges of the front
and back walls, you may change the
size of the vents a little.
Place the barrels.
Place six free-standing blocks down the middle of the dryer.
These will support the
barrels. Getting the barrels up off the
ground helps air to move around
them and also reduces the chance
of their rusting.
Put a layer of mortar on each of the blocks down the middle of the
dryer and on the center part of the
front and back walls where the
barrel ends will touch.
SPACING OF BLOCKS TO SUPPORT BARRELS>
* Lay the barrels in
place on the mortar and brace them temporarily
with sticks if they want to
roll. Make the chimney end of the
barrel assembly flush with the
outside edge of the back wall.
This should cause the front end of
the barrel assembly to lie most
of the way across the front
wall. Make sure the hole that will
let smoke into the chimney is on
the top of the end.
Seal the joints between the barrels.
Place a strip of screen
around each one and plaster with a
mixture of mortar, one part
cement to eight parts sand, and
Test the seals at
the joints. Light a smoky fire in the
or second barrel
from the front and see if smoke escapes anywhere
except the hole for
the chimney. Don't let it burn long
dry the mortar on
the joints. Keep the mortar damp until
Continue the walls.
Lay down five more layers of mudblocks.
Lay the blocks so that, as much as possible, each block crosses
over a joint between blocks in the
layer below. This will make
the walls stronger.
The air vents are only as high as the very first layer of blocks
Span over top of each vent with one full-size block.
To make good continuous layers of blocks you will have to cut
some blocks into smaller sizes.
Bring the blocks in the front and back walls as close as you
can to the sides of the barrels.
Fill in the spaces completely
with mortar so there will be no air
leaks. For added strength
you can mix some cement with this
If you think the ends of the barrels are not strong enough to
support three or four layers of blocks
above them, then make
crosspieces out of reinforced concrete
or use iron bars to put
across the top of the barrel ends.
Make them longer than the
width of the barrels.
Mortar them into place in the wall, and
make the tops even with the top
surfaces of the walls.
Make a drying floor screen.
Prepare screen to the right size for the drying floor.
whatever size sections you have by
overlapping about 5-10cm and
fastening together with thin wire.
The overall size should be about 3,30 x 1,80m.
This will allow
about 10cm on each side to be embedded
into the walls.
Check the size of the screen by stretching it lightly across
the top of the dryer.
If it overhangs beyond the outside edge
of any wall when it is centered, trim
it back. If it is too
small, add some screen where it is
needed. When you are
satisfied, set the screen aside.
Small-mesh screen is best. But chicken
wire can be
Place straw mats over chicken wire, or other
large-hole screen, so grain will
not fall through
Some kinds of woven mats are very
strong. These can
be used in place of screen.
In some places, screen
may be costly.
If you use mats in place of screen,
it would be best to prepare some
strips of metal
screen to embed around the insides
of the walls and
fasten mats to.
Then, if the mats later rot or weaken
around the edges (or anywhere),
there will be
something to fasten new mats to.
Place the drying floor supports and screen;
finish the walls.
Put a layer of mortar
down on the top of each
Lay the thirteen logs
down on the mortar,
from one side wall to
leave about 15cm between
each one and between
the log on each end and
the end wall next to it.
The 15cm may be a little
different; it will depend
on the size of the logs.
The log ends should come to
the outside edge of each side
Fill the spaces between the logs with mortar up to the tops
of the logs.
Build up the front and back walls and the corners of the
dryer to the same height as the tops of
While the mortar is still wet on the tops of the four walls,
lay the screen you have made in place
on top of the logs.
Center it so about the same width
extends over each wall.
Stretch any wrinkles or kinks out of
Place a thick layer of mortar over the screen the width of
the wall so that it fills the holes in
the screen and gives
a good base to lay mudblocks on.
Lay mudblocks in the usual
Lay down two layers of mudblocks above the screen.
make a drying chamber a little more
than 30cm deep, which should
be plenty for the most bulky grains,
such as unshelled maize.
Smooth any rough spots on the tops of the walls, so no bumps or
loose pieces will be knocked into the
dryer when it is in use.
Build a chimney.
Build a chimney
up against the back
wall of the dryer.
Center it on the smoke
outlet hole cut in the
end of the back barrel.
You can use mudblocks the
same size as in the dryer
walls, and mortar.
the 20cm edges vertically.
will give about a 12 x 12cm smokehole
in the center, which is large enough to
allow easy smoke escape,
but small enough to keep down heat loss
from the barrels.
Leave a space in the chimney wall against the hole in the barrel
It will start after two layers of blocks and be about two
Fill in irregular-size spaces in the brickwork with
cut blocks or mortar.
Center a full-size block over top of the
space you have made.
Continue laying blocks until the chimney
rises at least 1/2 meter above the tops
of the dryer walls.
This will keep smoke out of the drying
Make sure the chimney is sealed and free of cracks, so there is
only one way for smoke to go:
through the hole in the barrel end
and out the top of the chimney hole.
INSTRUCTIONS FOR USING THE OIL
<PIT BARREL DRYER
AND SIMPLE BARREL DRYER>
A shelter over the dryer will protect it and
drying grain from rains.
Build an open-sided one to overhang the
dryer at least 1/2m on each
side, and more on one side if you wish to
have room for storing fuel,
a work area, etc.
Gather dry wood, maize cobs or other fuel
before drying begins.
Build the fire in the first barrel or
mid-way into the second barrel.
Prop one of the cut-off barrel tops against
the front opening into
the barrels on a block or a rock to adjust
a good draft for the fire.
A piece of a barrel top can also be placed
part-way over the top of
the chimney to give you more control of
Watch and control the fire at all times
during drying. Do not dry
with too large a fire:
you may kill or scorch the grain.
size fire will give the best distribution
If you have trouble getting enough heat, in
the Simple Dryer you may
try partly covering the side vents to get
a better draft up around
You can modify the dryers by installing a
fan or fans to push a
steady flow of air up around the barrels
and through the drying
The resulting larger volume of less-hot air will dry the
grain faster and with little danger of
The dryers will take some time to reach
while the walls are heating.
Continue drying operations day and
night to make best use of the heat built
up in the dryer. Load
it with a fresh batch as soon as the one
before is dry.
Limit the drying temperature for food grains
to 50-55 [degrees] C. The
bottom layer of grain should not be too
hot to hold in your bare
Grains for livestock feed may be dried at higher temperatures.
Do not dry rice, beans or any grain to be
used for seed in these
dryers -- unless you install fans, and
even then proceed cautiously.
These grains must not be heated to more
than 45 [degrees] C.
Do not stir the drying grain.
Grain in the top layers receives
moisture passed up from the warmer grain
at the bottom, and gradually
releases it as drying is completed.
If you stir these wetter kernels
down again, they will re-wet the drier
kernels that got stirred up
the top -- and drying will take longer.
Stir only to release
the heat if overheating occurs.
Dry grain until the moisture content is
about 12%. Grain is dry
when a kernel is hard and breaks between
your teeth with a sharp
Load small grain such as millet and sorghum
in a layer 5-8cm deep.
Shelled maize and other grains may be
loaded up to 10cm, groundnuts
up to 20cm, and maize on the cobs up to
Maize may take one to two days to dry.
Do not let dirt build up in the dryer.
Do not let the air vents that
let air up around the barrels get
clogged. Keep the area clean.
Check for rust holes in the barrels and for
cracks in the joints.
Replace badly rusted barrels and re-seal
cracked joints. Smoke leaking
into the drying grain will discolor it
and change its taste and smell.
If you need to get up on the dryer floor
while loading or unloading
grain, avoid tearing the screen or mats
-- do not stand in the spaces
between the log supports.
If one of the logs supporting the screen in
the Simple Barrel Dryer
becomes weak or rotted, you will be able
to replace it by chipping
some of the mortar away from each end,
and pulling or knocking it
Slide in a new log and mortar the spaces around the ends.
THE PIT OIL BARREL
This dryer is based
on a plan prepared in 1974 by American Peace Corps
Volunteers in Benin,
West Africa. It is called the Oil
simply because it is
made from oil barrels. It actually has
depending upon the country where it was used.
first oil barrel
dryer was built in Samoa to dry coconut meat.
then, this dryer has
been built and tested in a number of countries,
and Benin. The dryer also is known as
the Low Cost
Bush Dryer and the
Proven advantages of
the Oil Barrel Dryer:
It is useful in areas where grain must be harvested in
Maize on the cob can be dried without long drying in cribs
and use of contact insecticides.
Construction materials are easy to find in most places.
Farmers can build the dryer with little
assistance or supervision.
It dries a lot of grain in a short time.
Grain can be harvested earlier.
Because there is less
drying time in the field, there
is less danger of insect
and rodent damage.
disadvantages (depending upon area or situation):
It is a better dryer for a group of farmers than it is for
One farmer would not need it very much
Sharing by a group of farmers means more use
less expense to each farmer in
The fuel used in this dryer is often firewood; sometimes
maize cobs also are burned.
Firewood is becoming harder
to get and more expensive in many places.
There is no fan included in this plan to force air through
the heating chamber and the
grain bed. Small gas motors
needed to drive fans often are
It should not be used for grain which will be used for
It would be worthwhile to find other economical natural
fuels (like maize cobs).
Banco construction (hand-rammed earth) works only where
there is a high clay content in
Fans placed to drive
the warmed air around the outside of the barrels up
through the drying
grain would increase the efficiency of the dryer.
will be necessary to
find a suitable power source for the fans.
where there are many
small motor bikes, it might be possible to construct
a power drive made
from a motor bike which permits temporary hook-up and
easy detachment of
the bike as a power source.
The dryer is made of
hand-rammed earth, known in different areas as banco,
terre de barre,
adobe, etc. The maize or other grain is
placed on a
floor. This floor is placed above a
firebox made of three
220 litre metal oil
drums joined together end to end.
You may substitute
an available local material that will be as strong and
resistant to wear
and heat as the banco, such as burned brick.
(cement and sand) or
concrete blocks will crack with the heat.
banco is already
used for construction in your area, the same high-clay
content soil will
work well for the dryer. You may mix in
low-clay soil to
allow you to build the earthen walls.
INSTRUCTIONS THROUGH BEFORE YOU BEGIN.
Tools and Materials
* 3 oil barrels, 220
[9m.sup.2] chicken wire or other screen, or a combination of
screen and woven mats
Iron or steel "re-rod" (reinforcing armature) for lintels.
6mm diameter, 6m long
Materials for concrete: 25kg
Heavy wire, about 2m
Thin wire, about 15m
10 logs, 8-10cm diameter; 2, 15m long
2 strips of small mesh screen, each about 180cm
long, and a few cm wide.
Select a site.
Find a place for the dryer which is high and well-drained.
If you dig too near a tree, roots will get in your way and
may damage the tree.
If you are in a swampy or drainage area,
water will get into the dryer and
wear away the walls.
Make 2 lintels.
The lintels are concrete horizontal slabs which will support
the weight of the walls over the
Make two forms out of boards or bricks.
Line them with paper.
The forms should each make a
finished lintel which measures
120cm x 30cm x 8cm.
Cut the re-rod into 6 equal pieces each measuring 1m long.
Mix concrete in this proportion:
1 part cement
Mix sand and cement thoroughly first, then mix in gravel.
add just enough water to make the
concrete thick and smooth,
but not watery.
Pour concrete into the forms up to a level of 4cm and tamp
Lay 3 pieces of 1m re-rod on top of the 4cm of concrete in
Space them evenly, with the outside pieces about
3cm from the edge.
Finish pouring concrete into the forms.
Tamp firmly and level
off the top surfaces.
Cover them and keep them out of the sun or cover with grass.
Keep them damp for about 7 days by
sprinkling three times
This slow drying cures the concrete to its greatest
Stake out the drying chamber and stoking
Stake out the drying chamber, as shown, on the site you have chosen.
It will be 2,80m x 3m.
Make sure the dryer chimney is staked out downwind of the
prevailing wind during the season when
the dryer will be used
This is important -- it keeps the smoke from blowing
back into the drying grain.
Stake out the stoking pit against the upwind 2,80m side of the
Make the stoking pit 2m x 2,lm.
One of the 2,lm
sides should be right next to the
upwind 2,8m side of the drying
Dig top soil out of the staked areas.
Dig the staked out areas to a depth where you come to hardpacked
earth that will make a good
foundation. We will use
30cm in this plan.
Pile all top soil to one side so it will
not get mixed with the banco when it is
later wetted and used
to construct the walls.
Dig a trench in the center of the staked out
Dig a trench centered in the middle of the drying area 70cm
wide and 140cm deep -- from ground
level. It should extend
4.80cm from the chimney end of the
drying area. This will
leave 20cm un-dug at the opposite end
for a retaining wall
for the stoking pit.
Keep the dirt you remove separate from the top soil you
Make cut-outs for the lintels.
Mark points at 2,70m and 3m from the chimney end on both sides
of the trench.
Remove the soil between these marks, and extending from the edge
of the trench to a distance 30cm
back. Dig it down 40cm.
will place the bottom surface 70cm up
from the trench floor.
Make two more slots up against the chimney end.
be 30cm wide, 30cm long and dug down
35cm, or until the bottom
of the slot is 75cm up from the trench
Make cut-outs for the chimney.
The chimney hole should be dug into the soil at the back wall
of the drying area.
Centered at the end of the drying area,
dig out an area 30cm wide, which
extends back 30cm beyond the
drying area to a depth of 30cm below
the ground level.
Also centered at this end of the drying area, dig another area
15cm wide, which extends 15cm
back. This channel will extend
below the hole just completed until it
is 50cm from the trench
Place the lintels.
Lay a 5cm layer of banco in each of the four lintel slots.
Lower the lintels into place.
Make sure they are level,
and square with the side walls of the
Build the dryer walls.
Make the front and back walls -- over the lintels -- 30cm thick.
Build the side walls up from the floor of the original 30cm deep
pit that you have dug out.
Make them 45cm thick until they
reach a height of 90cm above the base
of the front lintel. At
this point reduce their thickness to
30cm, leaving a 15cm wide
ledge on the inside of each side
wall. This ledge will support
logs for the drying floor.
The height you may build the walls in one day will depend on
the quality and consistency of the
Before the walls are too high, remove some of the dirt between
each side of the oil barrel trench and
the side walls. Make
a slope on each side of about 45 [degrees] starting at the inside edge
of the base of each side wall and
extending down to meet the
sides of the barrel trench about 40cm
above the floor of the
Embed a strip of chicken wire, or other wire mesh you have chosen
to use, into each of the walls, 10cm
above the 15cm ledge you
Each of the strips is 20cm wide and is as long as the
wall it is placed in.
10cm of the wire should stick out flat
into the drying area.
Later these strips will attach to the drying
Continue the front,
back and side walls until they rise 40cm
above the wire
strips. The top of the finished dryer
will be 75cm above
Build a retaining wall around the stoking
The retaining wall protects against erosion and will keep
dirt and trash from falling into the
Build the retaining wall up from the floor of the original
30cm deep pit that you have dug
out. Build it on three sides
of the stoking pit area.
The fourth side is spanned by the
front wall of the drying area.
Make it 20cm thick. The front
the stoking pit will fit exactly on
the 20cm ledge you left at the front
end of the 140cm deep trench that
extends down the center of the dryer
and stoking pit.
Build all three sides 50cm up from
This will bring them
20cm above ground level.
Build the chimney.
Build the chimney walls out of
banco up from the bottom of the
larger, top hole you have dug
out at the end of the dryer.
The inside faces of the chimney
walls should be flush with the
sides of the lower, smaller
hole that is dug into the
bottom of the top hole.
Extend the chimney 20cm higher
than the top of the back dryer
As you build upwards,
gradually narrow the inside
passage of the chimney until
it measures about 10cm x 10cm
at the top.
This will help
reduce heat loss.
Finish the stoking pit.
You may excavate any dirt that is left in the stoking pit
so that the dirt walls in the front
and opposite the stairs
are flush with the inside surfaces of
the retaining wall which
rests on them.
Cut stairs in the dirt next to the stoking pit.
Make four equal
steps each 30cm high and 40cm across.
Leave a ledge 30cm thick between the lowest step and the front
dryer wall, to help brace the dryer
Assemble and place the firebox barrels.
Cut both ends from two 220 litre barrels.
Cut one end from a third barrel.
Cut a hole 20-30cm across
near the edge of the other end of this
barrel. This will be
placed up against the opening at the
bottom of the chimney.
Punch four evenly spaced holes around the rim of each barrel
where it will join another barrel.
Join the three barrels together by tying pieces of heavy wire
through the punched holes.
Locate the barrel assembly in the trench with the small hole in
the end of the third barrel placed up
against the bottom
opening of the chimney.
Support the barrels on bricks about 10cm above the bottom of
Incline them slightly upwards towards the chimney
for easier smoke escape.
This will allow air to circulate all
around the barrels and will also
Seal the joints between the barrels by placing a strip of
screening around them and plastering
with a mixture of mortar
(1 part cement to 8 parts sand).
Close the trench around the barrel assembly ends under the lintels
Make sure you seal completely around the barrel at
the chimney end to prevent any smoke
"backflow". Close the
front end of the barrel assembly only
around the top of the
barrel to let cool air enter the
drying chamber -- this cool
air is warmed and will rise up through
the drying floor and
Test the seals at the joints.
Light a smoky fire and see if
smoke escapes into the drying
chamber. Do not let it burn long
enough to dry the mortar on the
joints. Keep the mortar damp
until it is hard.
Assemble the drying floor supports.
Use 10 logs of solid wood. The
logs should be 8-10cm in
diameter and 2.15m long.
Space the logs evenly across the drying chamber from one end
to the other.
The log ends will rest on the 15cm ledges in
the side walls.
Resting the logs on the ledges instead of
fixing them in place means they can be
replaced more easily
if they weaken.
Place and fasten screening on top of the log
Stretch screening across the logs and attach it to the 10cm
of wire mesh sticking out from each
wall. Make the
screening longer than the inside length
of the chamber because
the weight of grain will make the
screen sag between the logs.
Overlap all sections 5 or 10cm and
fasten together with thin
Small mesh screen is best. But
chicken wire can be used.
Place straw mats over chicken wire, or other large-hole screen,
to keep grain from falling through the
holes. Some kinds of
woven mats are very strong.
These can be used in place of
Fasten woven mats to wire mesh strips embedded
in the walls the same as you would
PHILIPPINES RICE DRYER
in the Philippines and other rice-growing countries have
discovered new kinds
of rice seed which grow more quickly.
This means the
crop is ready for
harvest sooner; often a farmer can plant and harvest two
crops in the time it
used to take for one crop.
However, because the
growing time is shorter, the rice is ready for harvest
during the rainy
season. Before, the rice would not be
ready until the rains
The farmer must harvest, but he cannot dry
his grain outside
in the sun.
The problem he faces is simple, and it is a
farmers all over the
world who must harvest during wet or humid times:
how to get the grain
dry before it is ruined by insects and molds.
at the University of the Philippines and the International
Institute in Manila, Philippines, have come up with answers.
They have designed
two versions of a dryer model they feel is relatively
to make, easy to operate and maintain.
We call it
here the Philippines
Rice Dryer. Each version of this dryer
will be discussed
There are advantages
and disadvantages to the use of this dryer by small
It can be used in the rainy season.
It uses less fuel than the oil barrel dryer because the
fan forces air through the grain and
It requires construction using relatively sophisticated
materials, tools, and skilled labor.
It burns fuel which can be costly.
It requires finding and paying for special machinery.
It is practical only for wealthier farmers or a group
<LOS BANOS RICE
The first rice dryer
is from the Grain Processing Program of the Department
Engineering at Los Banos, Philippines.
It has three main
a bin which holds the grain (placed on sheet
metal with holes) over
a container of hot
air (plenum); a fan to force air from the plenum through
the grain; and a
burner to heat the drying air.
A brief description
of the major parts of the Philippines Rice Dryer:
Grain holding bin
Floor area is 1.8m x 3.6m.
5cm x 5cm lumber.
Perforated sheet metal (sheet metal with holes).
58cm fan adapted from truck radiator fan.
Pushes 8.5 cubic meters per minute of air against a total
pressure of 2.5cm water column.
Size of the blower is chosen to fit the size of the grain
No stirring is necessary.
Mount fan with flange bearings, sheet metal housing.
Reinforce with angle bars.
5 hp gasoline or diesel engine.
V-belt and pulley.
A power tiller which has an 8 hp engine can be used.
43 [degrees] C recommended temperature so as not to damage milling
Developed direct flame kerosene burner.
Consists of 3-part
iron casing, needle valve between
burner and housing, and
a double shell sheet metal
housing. Uses 1.5 litres of fuel
V-tube manometer to read air pressure at plenum and to
set engine throttle.
Dial thermometer to show drying air temperature.
A. Kerosene Burner
Fan and Engine
Perforated Metal Floor
Notes on Operation
of the Dryer
It takes 2 men an hour to assemble the dryer.
This is the final
putting together of the pieces.
This is the time it takes if
the grain bin is already made and
all the parts are ready to
The dryer must be used under a shed to protect it and the grain
* The bin holds about
The manometer is a guide to engine speed: a 2.5cm displacement
of the water column shows the engine
setting is correct.
The temperature of the air for drying is adjusted by controlling
the flame through the needle valve and by adjusting
the distance between the burner
housing and the fan intake.
Drying continues until the top layer of grain is at 14%
(It will take about 8 hours of steady drying to
bring moisture down from 26% to 14
technical bulletins describing construction and use of the
The Project Director
Training of Technicians for Grain Industries
Department of Agricultural
University of the Philippines at Los
The IRRI Batch Dryer
is different from the early University of the Philippines
model in 2 important
It can use a self-feeding rice hull burner instead of gas
This burner uses 3-4kgs of rice hulls per
or 25kg per ton of rice dried.
One ton of rice contains 200kg
of rice hulls, so there are plenty
of hulls to feed the burner.
In other words, one ton of paddy
produces enough hulls to dry
that same ton of rice kernels.
The fan used is a 47cm diameter vane-axial type rather than
varying sizes and models of truck
radiator plans. The use of
a standard fan allows the operator
to fix standard drying times.
Other notes on the
IRRI Batch Dryer
Drying capacity is 1 metric ton.
It can dry this amount of
paddy rice in 4-6 hours depending
upon the initial moisture
content of the grain.
The oil burner uses a 3 hp gasoline engine (a 2 hp electric
motor can be added to drive the
blower). A kerosene burner
is installed in the air duct.
The rice hull furnace has a steel frame and is lined with
It consists of a combustion chamber and an
Either heating arrangement can raise the drying air temperature
from 29 to 43 [degrees] C at an air
flow rate of 30-35 cubic meters
of air/min/[m.sup.3] of grain.
Fuel consumption for the oil burner is 0.75 litres per hour
for the gasoline engine and 2.0
litres per hour for the
The rice hull furnace burns 3 to 4kg per hour of rice hulls.
This dryer, like the Los Banos Dryer, may be
hard to put together: in
some areas the materials may be expensive; in
other places the equipment
is hard to find.
These facts make it hard for many small farmers to use
such a dryer.
A group of farmers, however, would be more likely to be
able to use such a dryer cooperatively and
profitably. And the dryer can
be manufactured locally.
For more information and detailed engineering
Agricultural Engineering Department
The International Rice Research
P. 0. Box 933
The following plans
are based upon a construction manual written by James
McDowell as a result
of his experiences at the Caribbean Food and Nutrition
Trinidad. VITA technical artist George
C. Clark has
illustrations, as well as a simplification of the building
procedure of the
Model #1 dryer.
McDowell's plans in
turn were developed from the ideas and principles
of Dr. J. Lawand and
associates of the Brace Research Institute, McGill
Canada. Now with UNICEF in Kenya,
McDowell has used
the dryer to dry
grain from 25% to under 12% moisture in one day or less.
Solar Dryers have
several possible advantages
There are no fuel costs.
Sun drying time is reduced because the heat of the sun is
made stronger by covering the drying
grain with a double
layer of clear plastic film.
They can be used to dry other crops -- copra, cassava,
There can be
Temperatures in the dryer may build up to 65-80 [degrees] C.
means that grains such as rice, which
crack at temperatures
above 50 [degrees] C, or seed grains
(which can be dried at
temperatures no higher than 40-45
[degrees] C) can be damaged. A
farmer has to watch the grain
carefully, and, if no
thermometer is available, will have to
learn by trial
Dryers are most useful only at certain hours of the day
and would be of limited use during
long periods of
rainfall or very cloudy weather.
NOTES ON THE SOLAR
The dryer models
here were designed and tested for drying cereal grains,
root crops, fruits,
and vegetables. The dryer holds 8 to
11kg for each
square meter of
drying floor. Dryers of the size
presented here will dry
day. If a farmer wants to dry more
grain, he will have to
make a larger dryer
or build several dryers.
sketches for three versions of a Solar dryer are given
in the following
pages. These dryers can be made from
are most available
locally. The dimensions given here are
You can change the length, width, or depth
of these dryers
The sketches for
Models 1 and 2 are based on a useful, practical working
size of 2m in
length, 1m in width, and 23-30cm overall depth.
in area can be made
to suit local conditions, and dimensions of materials
The only dimension which should be followed as
closely as possible
is the thickness of insulation on the Model 1 box-type
Where wood shavings, wood wool, dried grass,
leaves, or similar
material are being
used, a minimum thickness of 5cm should be used.
the internal depth
of Models 1 and 2 should not be less than 15cm.
MODEL # 1 SOLAR DRYER
This model consists
of an outer box and an inner box. The
is at least 10cm less
in length and width, and at least 5cm less in depth
than the outer
box. The space between the boxes is
packed with suitable
Lower air holes are
drilled through the bottom of the boxes (and through
spacer boards fitted
in the insulation space for this purpose).
are cut in the upper
edges of the sides of the box to provide upper air
The dryer is supported about 15cm above the
ground on four legs
(which also form the
main corner members for the box)
READ THE INSTRUCTIONS
THROUGH BEFORE YOU BEGIN
Tools and Materials
Hammer, screwdriver, tri-square, saw, brace, and 2.5cm
wood drill, 2cm wood chisel.
Wooden planking or plywood for Sides, ends, and bottom
of boxes. Use wood
from old packing cases if it is
Lengths of timber:
4 pieces 5 x 10cm for legs
4 pieces 5 x 5 cm for legs
13 pieces 5 x 5 cm for the side,
end, and bottom
Insulating material: wood wool,
dried grass or leaves,
coir fibre, etc.
Nails and screwnails of appropriate size.
Flat or matt-black paint or other suitable black staining
material, e.g., charcoal, that is not
shiny or glossy.
Build the Inner Box
Check all measurements and markings on the wood before cutting.
Cut side and end pieces. These
can be one piece of wood, or
you can join narrower planks together
to make a box about the
Put the pieces together. Make
sure the nails are completely
hammered into the wood.
Cut and nail the leg pieces to the corners as shown.
Make the air outlet slots.
Mark the position of the air outlet slots on the
Cut out the slots in any of the three ways
Paint or stain the inside of the box with a dark color.
A flat black is good.
It is a good idea to put a wood
preservative on the outside if you have
it. Then paint
the outside with gloss paint or marine
varnish -- if
you can find them.
CONSTRUCT THE COVER
(FOR MODEL 1 and 2 DRYERS)
The same cover is
used for both dryers. It consists of a
wooden frame with a
central ridge piece. It is covered with
Tools and Materials
Saw (preferably tenon saw), screw-driver, sharp knife or
scissors, tri square, marking gauge.
Lengths of timber: about 5cm x
Transparent plastic (polyethylene) film (preferably .127mm
Screws (1.6cm x 8s C.S.).
Blued tacks (1cm) or large office stapler.
READ THE INSTRUCTIONS THROUGH
BEFORE YOU BEGIN
Make the frame so
that its length and width are each 8cm greater than
the box to be
covered. The cover will overlap the
dryer box by about
4cm in each
Make the Frame
Cut the pieces for the frame to the right lengths.
* Put them together as
Dry the frame in the hot sun before putting on the plastic.
Put the Lower Plastic Sheet on the Frame
Put the cover on while the wood is still warm and at a
time when humidity is low.
These precautions are necessary
to prevent condensation (fogging)
layers of polyethylene.
Cut a piece of plastic sheet for covering the lower
side of the frame so that it is 8cm
wider and 8cm
longer than the frame.
Turn the frame upside down and lay
the plastic sheet in place.
one side of the polyethylene back
on itself to form a triple layer
seam 2cm wide.
* Start at the middle of
the frame and work toward both ends.
Stretch the plastic lightly but firmly
or staple through the seam at 8cm
intervals to fasten
this edge of the polyethylene to the
frame. DO NOT OVER-STRETCH
POLYETHYLENE WILL "GIVE" AND DISTORT
IF FINGERTIPS ARE DUG INTO IT.
SUCH DISTORTED AREAS ARE
LIKELY TO BREAK THROUGH DURING
USE. IT IS BETTER THAT
POLYETHYLENE SHOULD BE SLIGHTLY LOOSE
RATHER THAN OVER-STRETCHED.
Repeat this process at the other side of the frame.
Stretch the polyethylene across the
frame while tacking
Fold similar seams at each end.
Tack the ends of the
sheet to the frame.
Tuck the plastic neatly at each
Fasten firmly in place.
3 Put the Upper
Plastic Sheet on the Frame
Cut a piece of polyethylene sheet for covering the upper
This sheet, when placed over the frame, should be
10cm wider and 10cm longer than the
frame. Turn the
frame upside down and, making a triple
fold seam as
before, tack or staple one edge to one
side of the frame
so that the seam overlaps the triple
seam of the lower
Stretch the polyethylene over the ridge and around to the
lower edge of the other side
member. Make a folded seam
and tack or staple in place as before.
Stretch the polyethylene over one end of the frame, fold
and tack as before, cutting away any
extra material resulting
from the slope from ridge to side
the corners of the sheet in neatly,
and tack firmly in
Repeat for the other end of the frame.
Attach the Covers to the Dryers
The covers do not weigh much and are likely to blow off the
dryers even in a light wind.
The cover can be kept on by
fastening hooks of stiff wire to each
corner of the cover
and swinging these hooks into place
around nails or pegs
fixed in the sides of the dryer.
Or, fasten lengths of strong twine or cord to one side of
the dryer, draw them tightly across
the cover, and tie
them to nails or pegs on the other
CONSTRUCT THE DRYING
This is a simple
wooden frame with fine wire mesh stapled to its underside.
Two support runners
are nailed to the underside (over the edge
of the wire
mesh). If necessary, two small pieces
of wood may be tacked
over the edges of
the wire mesh to hold it in place at the ends.
folding the edges of
the mesh over upon itself before stapling may be
all that is needed.
Make two trays, each
slightly smaller than 1m x 1m so that it will fit
the dryer box
well. It is a good idea to make two
trays because they
are easier to handle
than one large tray. Also, using two
that grains at two
different moisture levels can be dried at the same
Simpler trays may be
made from local materials. Papyrus reed
or a frame with
slats of reed or split bamboo, for example, make an
excellent support on
which material can be dried. Coarse
sacking material, or
open weave grass or fibre matting stretched on
a frame also can be
MODEL #2 SOLAR DRYER
This dryer also is
for a 2m x 1m dryer. But it is not
portable like the
Model #1 Solar
Dryer. It is built on a permanent
location and is made
with clay bricks, or
similar material. Bricks composed of
and cement and
compressed by a CINVA-RAM work very well.
bricks are used, the
hollows should be packed with dried grass, coir
fibre, or other
Choose a Site
A good place for the
Solar Dryer will be
high ground which is flat and level.
Make sure the location
is well drained.
out in the open -- not shaded by trees or buildings.
exposed to the prevailing wind.
The end of the dryer
should be facing the prevailing wind.
Tools and Materials
Large knife, axe, or machete
Coping saw or wood rasp
Clay bricks or bricks made from similar material
Mortar or clay for laying bricks
Thick bamboo (6 to 7.5cm diameter)
READ THE INSTRUCTIONS THROUGH
BEFORE YOU BEGIN
Lay out dryer size by building up the corner blocks.
Prepare a floor of hard-packed earth or concrete mortar.
Dig a drainage trench around the dryer to protect it from
The trench should be 23-30cm wide and 23-30cm
Prepare Bamboo Pipes
Choose bamboo of even thickness with as few joints as
Cut bamboo to the same length as the width of the dryer.
Then prepare the pipes as follows:
Cut holes, about 4cm in diameter, in each pipe.
can be made by using one of these
Finish the Walls
Place the bamboo pipes in position in the second layer.
Cut the blocks short as necessary to
fit in the bamboo
Put down the third layer of bricks.
Pack the holes around the bamboo with mortar or clay.
Put down the top layer of bricks and cut out the air
outlet slots or lay the top layer of
one inch gaps as air-outlet holes
spaced along the
Paint the Inside
Paint the inside of the dryer a dark color.
mixed with clay and water may be a
Construct Cover and Drying Trays as for
MODIFICATION OF MODEL #2 SOLAR
It is possible to
build solar dryers which can work on solar heat for most
of the time, but
which can, if necessary, be artifically heated during
periods of heavy
clouding or rain.
A modification of
the Model 2 dryer will allow for this dual-purpose
This modification consists of building-in a
metal flue pipe
which runs through
the length of the dryer. This pipe
carries the heat
from a firebox built
at one end of the dryer. When drying
has to be done
conditions, the fire can be lit to provide heat for drying.
Either one large,
say, 11cm diameter pipe, or a number of smaller pipes can
When using smaller pipes, difficulties in
constructing a manifold
But it may be possible to adapt an exhaust
manifold from an
old gasoline or
diesel engine for this purpose.
THE ONLY BASIC
MODIFICATION NEEDED IN CONSTRUCTING THIS DRYER IS THAT THE
WALLS MUST BE BUILT
HIGH ENOUGH TO ALLOW THE FLUE PIPE TO PASS UNDER THE
An increase of 7.6cm
(or one brick) in height, should be sufficient.
The firebox may be
built in clay or brick, or a section cut from an old
oil drum may be used
for the purpose.
The base of the
firebox must be at a lower level than the dryer.
Make sure that this area is protected from any flooding which
may occur during heavy rains.
The flue tube
running through the dryer should slope upwards towards the
chimney to assist
When using artificial heat, the movement of
air through the dryer by
operate as it does when solar heat is being used.
depending upon the
heat given by the fuel being used, it may be necessary
to close-off more of
the upper ventilation ports.
Make sure that the part of the flue pipe passing through the
dryer is smoke-proof.
If it is not smoke-proof, smoke will
flavor the foods being dried.
A damper should also be placed
in the chimney. This damper must be
kept closed when sun-drying
is being carried out, or the flue pipe
may exert a cooling effect.
Make sure to site this modification so that the firebox end
faces into the prevailing wind.
This will assist draught through
the flue, and will also ensure that
any sparks from the chimney
are carried away from the polyethylene
MODEL #3 SOLAR DRYER
This is a simple
dryer. It is not as efficient as the other
conditions where it
is exposed to cooling winds, but it will provide
drying than direct exposure to the sun, and will also
protect the drying
material from rain. It is essentially a
Of two sheets of
corrugated galvanized iron roofing material placed so
that they form a
series of tubes. The lower sheet is
bedded in insulating
material to reduce
loss of heat. It is set in a sloping
with one end raised
about 15cm higher than the other. This
allows hot air to
rise and escape at the upper end, creating a draught of
air over the
material being dried. The material
which is being dried is
placed in the
hollows of the lower sheet.
There are a number
of possible ways of siting and constructing this dryer.
It can be
permanently sited or made portable.
Certain refinements can be
added to increase
its efficiency. For this reason the
construction of a
model will be described first; possible modifications will
be described later.
The Portable Dryer
In this model, the
corrugated sheets are fastened to a shallow wooden box
which contains a bed
of insulating material. The box will be
high and 80cm
wide. The dimensions of the box will
depend on the final
size of the prepared
corrugated sheets, so the sheets are prepared first.
Tools and Materials
Hammer, saw, tri-square, wood chisel, pliers
2 sheets corrugated galvanized iron
Timber for bottom and sides of box
Nails or coat-hanger wire
* Black paint
Prepare the Sheets
When purchased, the sheets will be packed closely together.
Turn the upper sheet 180 [degrees] so
that the sheets are on top
of each other.
The upper sheet will tend to slip sideways
and will not remain evenly positioned.
Mark a line along the edges of
each sheet about 1cm from the
Using pliers, and moving
gradually along the sheet, bend
the edges down to form flanges
which are level with the plane
of the sheet.
Once the edges
have been bent into position,
lay each flange along the edge
of a piece of wood and beat with
a hammer until it is flat and
The sheets will now
lie properly together in the
Hinge the Sheets
The sheets must be held together so they can be easily positioned
during future use.
This is done using wire rings.
Wind a piece of suitable wire spirally around a 1cm diameter
form (e.g., the handle of a wooden
spoon) to form 6 loops.
Remove from the form and pull the ends
of the wire so that
it forms a loose spiral.
Cut this spiral with the pliers
so as to form a number of rings with
Punch five holes through the flanges at one edge of each
sheet, using a nail and a hammer.
These holes should be
positioned as follows:
one hole about 7.5cm from each end
of the flange, one hole in the centre
of the flange, and
two holes midway between these holes.
Pass the wire rings through these
holes and close the
rings by pressing the ends
together. This effectively
hinges the sheets together and allows
Prepare the Dryer Box
The shallow support and insulating box can now be constructed
to fit the dimensions of the lower
sheet of corrugated iron:
cut slots in the upper edges of the
one side of this box to
provide space for the hinge rings.
Pack the box with insulating material, e.g., wood wool, dried
grass or leaves, or other similar
Place the corrugated sheets in position and fasten the lower
sheet to the frame by nailing through
the flanges along each
edge and through the points where the
sheet contacts the ends
of the box and the central support
Close the openings at each end between the corrugations of
the sheet and the wooden frame by
filling with cement, plaster
Paint the Dryer
Paint the upper surface of the top sheet with a flat black
Using a suitable primer to be sure of sticking to
Treat the wood of the box with preservative, or paint with
gloss paint if available.
USING THE PORTABLE
Site with the length of the dryer in a north-south
direction, preferably in a position
where it is sheltered
from the wind.
Raise one end so that it is 15cm higher than the other.
Make sure the rays of the sun strike the upper sheet as
directly as possible.
(The end to be raised will depend
on the latitude and season of the
year. For example, in
latitudes more than 5 degrees north of
the equator, the
northern end of the dryer should be
raised in winter
and the southern end in summer.)
Protecting from Rain
There is a risk that
driving rain may enter the upper end of the dryer
and wet the
contents. It is thus necessary to fit a
shelter plate to the
upper sheet at this
end of the dryer.
Nail a wooden batten across one end of the upper surface
of the top sheet.
Nail to this wood a strip of metal which is the full width
of the sheet, and which will jut out
about 15cm beyond the
end of the dryer.
This metal can then be bent downwards
in a gentle curve at its outer edge so
as to shelter the
open end of the dryer.
The efficiency of
the Model 3 dryer can be greatly increased by fitting
a polyethylene cover
over the top metal sheet. The plastic
insulating air space
between the polyethylene and the corrugated sheet.
Build a simple wooden frame over the top sheet using two
vertically placed battens along each
of the flanges, and
two joining battens across each end of
Fill the spaces between the corrugations and the end battens
with plaster, clay, or cement.
Stretch a single sheet of polyethylene
over the frame.
Tack or staple the sheet in place.
Keep the slots in the side piece of the frame (necessary to
accommodate the hinge rings) as small
as possible. They should
only be cut enough to allow clearance
for the rings.
cover will protect the upper corrugated sheet from the
cooling effects of
wind and rain. It also insulates the
dryer so that
temperatures are possible.
SITED MODEL 3 DRYER
The dryer described
above can be permanently sited on a clay platform,
thus avoiding the
need to construct a support and the lower insulating
The clay platform will provide
insulation. This type is built as
Flange the sheets and hinge together as described for the
Nail wooden battens about 4cm x 2cm across the lower side
of the lower sheet at each end and at
the middle, to
Construct a simple sloping clay
platform the size of the
lower sheet and 15cm above ground
level at one end and
30cm above ground level at the
other. Mix large quantities
of dried grass or leaves with the
While the clay is still wet and soft,
bed the lower sheet
in position so that the clay moulds to
of the sheet.
Allow the clay to harden.
Make sure to site this dryer in a position
which will give the
most effective exposure to
the sun at the time of year when
the most drying is being
Start drying as
early as possible in the day to get maximum exposure to
Once material has been placed in the dryer
and the cover placed
in position, do not
lift the cover until drying is completed for the day:
taking the cover off
will allow a lot of heat to leave the dryer.
Brush the dryer out
daily to get out dust, and to remove any pieces of
spilled from drying trays.
Keep the drying
trays clean; wash them often.
temperature inside the dryer by opening or closing the upper
Temperature may be measured by putting a
thermometer in one
of the upper air
outlets. When doing this, shade the
direct sunlight by
inserting a card beneath the cover.
measured in this way
will be the maximum (not necessarily the average)
Or, temperatures at
the level of the drying material may be measured
by drilling a hole
through the side of the dryer and inserting a thermometer.
Again, make sure
that the bulb is shaded from direct sunlight.
Closing the upper
ventilation outlets will increase internal temperatures.
However, if moisture
begins to collect inside the dryer you must start
opening the outlets.
In cases where
opening all the upper outlets still results in temperatures
which are too high
for the material being dried, additional outlets should
be cut in the upper
edges of the sides.
particularly green vegetables, carrots, plantain and some
varieties of sweet
potato, may lose color and Vitamin A during direct
sunlight. For these materials, shade
drying is useful (but
To do shade drying,
fit sheets of thin metal immediately below the cover.
Paint the metal
(galvanized sheet or beaten-out tin containers) black on
The size of the metal sheet should be just
less than the
internal length and
width of the dryer. Support the sheet
on nails driven
into the inner sides
and ends of the dryer. Put the nails in
not more than
the upper edges of the sides.
Make sure the sheets
do not touch the lower side of the polyethylene cover
heat may cause it to melt). But the
sheets should be
high enough so that
hot air from beneath the sheet can still escape
through the upper
properly, as described above, these sheets will send almost
all of the heat they
receive to the air inside the dryer, and
temperatures are similar to those made by sunlight.
metal shading sheets
can, in fact, assist drying, since their presence
effective convection air movement through the dryer.
If fogging occurs
during use, withdraw tacks or staples from a short
length at each end
of the cover, open up the polyethylene to allow moisture
to escape while the
dryer is in operation, and then refasten the
modification to either the Model 1 or Model 2 dryers, which
efficiency of drying during periods of intermittent clouding
or rain, is the
placing of a layer of dark-colored (or black-painted)
stones in the bottom of the dryer.
These stones should be
egg sized or
During periods of
sunshine, the stones will become heated.
Then when the
sun is covered by
clouds, the stones maintain the internal temperature
by giving up heat to
DRYING GRAIN CROPS
To make sure crops
do well in storage, they should be carefully dried,
either "in the
head" or after threshing, before they are placed in storage.
If dried "in
the head," grains should be threshed before storage since
closely packed grain
is less subject to insect attack.
Groundnuts can be
dried either in the shell or after shelling.
in the shell
provides protection against insect attack.
may be harvested before pods are quite ripe and dried
in trays with very
fine mesh bottoms. It will then shatter
in the dryer.
But since all the
seeds will be retained, this method of dealing with
sesame has great
should be spread in a 1cm to 4cm deep layer on drying
trays of appropriate
mesh size, so as to give a loading of about 7-10kg
meter. For bulky material such as
unthreshed finger millet
or sorghum, layers
up to 7.5cm deep can be used. For
groundnuts in the
shell, layers may be
up to 5cm deep.
For very small
seeds, such as finger millet or sesame, trays with a very
fine mesh will be
needed. Mosquito netting or tightly
sacking would be
contains some examples of different ways of presenting
information. The examples are from
Asia, Africa, and
South America, thus
highlighting the fact that good grain storage is
an important subject
all over the world.
GRAIN STORAGE IN MUD CRIBS
Botswana designs of mud cribs are
easy to build and
the materials cost very little. By
taking more care
over some details during construction,
you can reduce the
risk of insect damage to stored grain.
Issued by the
Department of Agriculture, Information Service, Private Bag 27, Gaberones.
BUILDING A MUD CRIB
Choose a place where
the ground is firm and well drained, because a crib full of grain is
heavy and may sink into soft or wet ground.
Bring several large,
smooth stones and bury them firmly in the ground to form a base.
Use strong, straight
poles for the main crib supports and lay them on the stones.
notches or fix pegs at the ends of these
poles to prevent the floor poles from slipping.
Make a floor of mud
and build up the mud walls.
Reinforce the mud ceiling with poles.
Make an outlet at
the bottom of each compartment to permit easy removal of grain.
empty coffee or dried milk tin with a lid of
the press-in type. First cut out the
then build the tin into the wall at floor
Build the walls
right up to the ceiling so that each compartment is completely separate
and there is no chance of insects moving
from one compartment to the next.
Plaster the inside
walls and ceilings. Insects hide in
cracks and crevices and in the poles
of the ceilings.
Therefore plaster the ceilings also, so that there is no gap
the walls and ceilings.
Cover the completed
mud crib with a thatch roof supported on separate poles.
should be thick and rain proof especially
along the ridge. The roof must also
well beyond the crib so that rain cannot
reach the mud walls, and the hot rays of the
sun never shine on the crib.
The plug for filling
the crib should be smeared over with mud to make the crib airtight
and insect proof.
Grain is removed by opening the lid of the tin at the bottom of
USING A MUD CRIB
The crib should be
repaired before each harvest. Mend the
thatch and re-plaster over
cracks in the walls, floor and ceiling.
Thoroughly clean out
the empty crib by brushing. Do not keep
old baskets, skins, sacks,
etc. on top of the mud crib.
These things harbour the beetles that attack
grain and it
is easy for them to walk into the crib.
Make sure that new
grain is always quite dry and has been winnowed or sieved before you
put it into a
crib. Never mix new grain with old
grain remaining from the previous year.
To stop insects
damaging your grain, admix Kopthion or Pyrethrum dust (1 packet of dust
to each 200 lb. of
grain.) These insecticides are
preferred but the ash from cattle dung or
wood may be
used. Mix not less than one bucket of
sieved ash with each 200 lb. of grain.
condition of your grain every 2 months by removing a sample and looking for
If you find them, remove the grain, winnow
it and admix Kopthion or pyrethrum
before returning it
to the crib.
Grain intended for
human consumption should be first sieved or winnowed and washed - especially
if it has been treated with insecticide or
If you would like
further help, ask your Agricultural Demonstrator.
KEEP THIS LEAFLET FOR FUTURE REFERENCE
Printed by Government Printer
HOW TO ....
GRAIN IN STORAGE
SAVE GRAIN CAMPAIGN
(Country Wide Programme)
DEPARTMENT OF FOOD,
Apply the 5 Golden Rules:
Dry and clean your grain before storing.
Use dunnage to avoid moisture damage to grain
stored in bags.
Use domestic bins or improve your storage
Fumigate with EDB ampoules to avoid insect
Use anticoagulant for rat control.
FOR ADVICE ON YOUR
PROBLEMS AND TRAINING
CONTACT ANY OF THE
IN PERSON OR
SAVE GRAIN CAMPAIGN
Department of Food
Post Box No. 10
Post Box No. 7823
Post Box No. 509
Post Box No. 22
Post Box No. 158
INDIAN GRAIN STORAGE INSTITUTE
PRESERVE CORN SAFELY IN
Division of Stored Products-Extension
Asistente de Extension de
Agro. Francisco Estrada
EVITE PERDIDAS DE SU
MAIZ EN LA TROJA.
Cada ano, durante el periodo comprendido
entre la cosecha y el momento en que
el producto llega al
consumidor, el exceso de humedad del grano, el ataque de
insectos y pajaros, originan perdidas considerables al agricultor
y al comerciante.
La manera de evitar tales perdidas, es el
control sobre las causas antes mencio
nadas, mediante un
manejo eficiente de los granos, y dandoles una adecuada proteccion
La humedad, el primero de estos factores,
puede controlarse de una manera
un buen secamiento del grano, antes de guardarlo en el almacen
o granero; bajando
su contenido de humedad hasta un 12% o sea cuando este bien
LOSSES OF YOUR CORN IN THE BARN
Each year, during the period between the
time of harvest
and the time when
the grain reaches the consumer, there are
for the farmer and merchant. These
are due to excess
grain moisture, the attack of rodents, molds,
insects and birds.
These factors affect
the good storage of grain
The best way to prevent such losses is to
causes by proper
handling and adequate protection of the grain
Dampness, the first of these causes of
grain loss, can be
effectively by good drying before storage. The safe
moisture content for
corn is 12% or lower.
PRODUCT TO 12% OR LOWER
Practicamente, podemos calcular, si la
humedad en el grano esta buena para
al morderlo, este se quiebra, sin presentar elasticidad y que
no este lechoso.
Tambien podemos saber que el grano no esta
aun bueno para almacenarse, cuando
al introducir la
mano entre estos granos, sentimos el calor proveniente de ellos,
que por exceso de
humedad se encuentra en plena actividad respiratoria; en cambio,
se sentira fresco el
grano cuando debido al secamiento, haya disminuido dicha actividad;
entonces los granos
estaran reposando y podran ser almacenados, sin mucho
riesgo de que se
desarrollen hongos, y sin peligro de que se pudran.
La humedad y el calor excesivos, son
ambientes propicios para que se desarrollen
ocasionaran dano al producto que se almacena.
El dano por roedores puede evitarse en gran
parte proporcionando al local de
adecuada proteccion, contra el acceso de las ratas.
alrededores del granero limpio de malezas y desperdicios, ya que
prefieren no movilizarse por sitios despejados.
Es muy efectivo para su control el uso de
raticidas en forma de cebos, de los
que se venden en el
comercio, tales como Racumin, Zelio, etc.
No se deben dejar estos cebos al alcance de
los ninos ni de los animales domesticos,
porque son productos
In practice, we can check the moisture
content in the grain
which is safe for
good storage by biting it. Dry grain is
so it will break
with a sharp crack, rather than crushing easily
like wet grain.
We can also find out if grain is in good
condition for storage
by touching it.
If we feel heat rising from the grain, it
is too wet.
If the grain is excessively wet, it will
producing heat and
moisture. On the other hand, dry grain
If grain is giving off heat, it should be
assure storage without risk of mold development
Moisture and excessive heat are favorable
the growth of molds
which will damage the grain.
Damage by rodents can be avoided to a large
storage area against the invasion of rats.
areas of the granary should be kept clean of
weeks and garbage as
rodents prefer not to move through open,
The use of pesticides such as Racumin,
etc., in the form of
bait, is effective for control of rodents.
These pesticides should not be Left within
the reach of
children or pets
because they are extremely poisonous products
and can cause
serious illness or death. Rat poisons
always be used very
carefully, following recommended instructions.
El dano por insectos, es el que
generalmente causa mayores perdidas en los
productos que se
almacenan. Su control se debe ejercer
desde el momento en que
esta comenzando a
florecer en el campo el maiz que se piensa cosechar y almacenar.
En este tiempo en
que ya esta espigando el maiz, los insectos pueden estar en
infestada, cercana al plantio de maiz; vuelan hacia el campo en busca
de nuevo alimento y
comienzan a penetrar la mazorca por las aberturas de la tuza:
facil la penetracion, cuando esta tuza ofrece escasa protection
Es por esto que algunas variedades
mejoradas, se pican mas facilmente que las
pues estas, generalmente poseen buena cobertura.
PLACEMENT OF BAIT FOR
IN PLACES TRAVELED BY
OF THE REACH OF CHILDREN
AND FARM ANIMALS
Generally, the greatest losses in stored
caused by insect
damage. Insect control should be
from the moment the
corn is beginning to mature in the field
through the time
when the corn is harvested and stored.
may be in an
infested barn, near the grain field, flying through
the field in search
of new food, or already beginning to
penetrate the ear of
corn through openings in the corn husk.
The only natural
protection of the ear of corn is the husk, which
can be penetrated by
Some of the newly developed varieties of
corn have husks
which are more
easily penetrated than traditional domestic
Extra precautions against insect invasion
need to be
taken with these
THE CYCLE OF INFESTATION
BEGINS IN THE
PREVENT INSECTS FROM
FLYING TO THE FIELD
DESTROY INFESTED REMAINS
AND CLEAN THE BARN
SELECT ONLY HEALTHY
EARS OF CORN
111 SQUARE YARDS
OUNCES (175 c.c.)
MALATHION LIQUID 57%
In order to prevent infestation in the
field, the granary
should be cleaned of
all the remains of the previous harvest,
which may be
infested, and these remains burned or destroyed.
Next make an
application of Malathion liquid of 57% by diluting
17 1/2 spoons (16
oz.) of this insecticide in a gallon of water.
Using a sprayer,
completely cover the ceiling, walls, and
floor surfaces of
the granary. With a gallon of this
a surface of 111
square yards can be covered.
LIQUID ON THE
WALLS, CEILING AND FLOOR OF THE
SWEEP AND CLEAN THE
Al llevar el maiz cosechado hacia la troja
o granero, para almacenarlo, se deben
mazorcas sanas, evitando guardar mazorcas picadas que infestarian
a las otras
No se debe dejar el maiz ya maduro doblado
o sin doblar en el campo, por mucho
tiempo, porque queda
expuesto a la infestacion de insectos y al ataque de ratas
y pajaros, durante
un periodo mas prolongado. Se debe
proceder a la cosecha, tan
pronto como lo
permitan las condiciones del ambiente y el contenido de humedad del
Para proteger al maiz que se va almacenar
en trojas, se recomienda aplicar el
Malathion en polvo al 2%. Este se debe
aplicar por capas, es decir colocando
primero, sobre el
piso donde estara la troja, una ligera capa de insecticida,
despues se coloca la
primera capa de mazorcas, luego otra capa de insecticida,
y asi sucesivamente
hasta dejar la troja llena a la altura deseada.
que se recomiendan
para el uso de este insecticida estan de acuerdo al tamano de
Asi, tenemos que para los hibridos y
variedades mejoradas, como
el tamano de la
mazorca es un poco grande, hay que aplicar una onza de Malathion
2% en polvo
(Triangulo Verde) por cada 100 mazorcas con tuza.
Para las variedades
criollas, como las
mazorcas son mas pequenas, se debe aplicar una onza del
insecticida por cada
150 mazorcas con tuza.
When the harvested corn is brought to the
granary for storage,
the best ears of corn should be selected.,
avoiding the storage
of ears which are already infested with
insects, as these
insects can easily infest other ears of corn.
SELECT ONLY HEALTHY
EARS OF CORN FOR STORAGE
The ripened corn, whether piled on the
ground or still
on the stalk., should
not be left in the field too long because
over a prolonged
period of time it is exposed to the
attack of rodents
and birds. The harvest should be
out as soon as the
climatic conditions and moisture content
of the grain permit.
To protect the corn to be stored in
barns, it is
recommended that 2%
Malathion insecticide in powder be applied.
This should be applied in layers.
First, dust a thin
layer of insecticide
on the floor where the grain will be
Next, after the first ears of corn are
another layer of
insecticide and so-on until the barn is filled
to the desired
level. The doses recommended for the
use of this
insecticide are in
accordance with the size of the ears of corn.
Thus, we have to
apply one ounce of 2% Malathion in
(green triangle) for
every 100 ears of hybrid and newly developed
As the ears of the native varieties are
ounce of insecticide
for every 150 ears should be applied.
Este polvo debe ser espolvoreado sobre la
superficie de todas las mazorcas, de
modo que las proteja
totalmente. Se puede lograr una
aplicacion uniforme, utilizan
do una media de tela
de Nylon o cualquier bolsa de tela rala, que permita al polvo
hasta las mazorcas.
Se debe aplicar exactamente la cantidad de
insecticida que se recomienda y seguir
indicados, para evitar malos efectos del polvo por una defectuosa
APPLICATION OF INSECTICIDE IN CORN
POWDER (GREEN TRIANGLE)
EVERY 100 EARS
FOR EVERY 150 EARS
This powder should be sprinkled on the
surface of all
of the ears of corn
in a way that totally protects them. A
may be obtained by using a nylon sock or
any sack or bag with
a loose weave which permits the powder to
be filtered easily
through to the ears of corn.
Apply 2% Malathion
In order to avoid problems caused by the
insecticide, the exact recommended quantity
should be used and
the indicated methods followed.
contains excerpts from an article which appeared in
Products Information in 1971. It is
to give you some
idea as to the types and number of moisture meters
available. A Table included at the end
of this article
also lists the names
and addresses of the manufacturers and/or suppliers
of the meters so
that you can write for further information.
material is taken from Tropical Stored Products Information,
Institute, 1971 VOL. 21
GUIDANCE IN THE SELECTION OF
FOR DURABLE AGRICULTURAL
The three principal
sources of information available to the prospective user are (1) newspapers,
and journals, (2)
manufacturers' brochures, and (3) organizations in a position to give unbiased
magazines and journals, which occasionally contain information about meters,
the Financial Times,
Electronic Age, and Power Farming.
Whilst manufacturers are always helpful in
supplying plenty of
information about their own range of meters, information about a much wider
meters will be more
likely to be obtained from organizations having unbiased interest in these
Examples of such
organizations are (1) Tropical Stored Products Centre, (Tropical Products
Slough, England, (2)
Grain Storage Department, Pest Infestation Control Laboratory, Ministry of
Fisheries and Food,
Slough, England, (3) National Institute Of Agricultural Engineering, Wrest
England, (4) Grains Division, Agricultural Marketing Service, United States
Agricultural Research Centre, Beltsville, Maryland 20705, USA.
Articles on moisture meters
sometimes appear in
the publications of these and other similar organizations.
Tables I and II give
details of some available moisture meters, particularly how they can be
the commodities with
which they may be used. These details
are based upon information provided by the
manufacturers of the
With every piece of
information, it is important to ask the question:
is this information sufficient for a
decisive opinion to
be formed about the meter? Where the
answer is `no', further enquiries should be made.
Factors to Consider
in Making a Choice
It can be seen from
Tables I and II that for any specific purpose, several meters can be found,
problem of choice a
real one, indeed. A satisfactory
selection is likely to be achieved when adequate
thought has been
given to the following factors:
1. Meter types and their implications.
2. Characteristics of the commodity.
3. Requirements of the work for which a
meter is sought.
4. Business considerations.
implications of Meter Types
indicate the principles upon which the action of their meters is based.
of the implications
of such principles will, no doubt, be of considerable value in deciding which
several meters will
be the most suitable. The meters
commonly used with durable agricultural products
fall into five
groups, according to the principles of their action:
Those involving chemical interaction between calcium carbide and the
product water, with the
evolution of acetylene gas, the
pressure of which is subsequently measured.
Those involving heat-drying of the product, the attendant loss being
ascribed to evaporated
Those involving the measurement of electrical conductivity (or
resistance) of the product, since
the value of this property is
relatable to the moisture content, within a suitable range of
Those involving the measurement of the dielectric constant of the
product (or capacitance of
the electrical system of which the
product is a component), since the value of this property
changes with the moisture content,
within a suitable range of moisture contents.
Those involving the measurement of that atmospheric relative humidity
which is in equilibrium
with the product moisture, since,
under equilibrium conditions, there is a definite relationship
between the moisture content of a
product and the ambient relative humidity
Heat-drying methods require a
suitable source of power-supply or fuel, which may not be
Methods based on the evolution of acetylene
gas require regular, supplies of fresh calcium
carbide, which is
not a safe commodity to handle by post, because of the risk of explosion.
relative humidity require, firstly, a
knowledge of the relationship between the produce
moisture content and
the relative humidity of the inter-granular air:
secondly, a periodic check on
and thirdly, in some cases, large quantities of produce which must have
for sometime prior
meters are faster, and in the main, less demanding on calibration checks, but
servicing. Also, they give less
reliable readings outside the middle region of the range of moisture
contents for which
they are calibrated. The accuracy of
the probe-type electrical meters is affected
by variations in the
pressure exerted by the produce on the electrodes, while the consistency of the
of those meters
which measure the dielectric constant is affected by inconsistent packing of
sample in the test
Attention has been
focused above on the less favourable features of the meter groups mainly
are more likely to
be overlooked. Information on the
merits of any meter will not normally be difficult to
obtain, and Tables I
and II show the relative merits of the meters discussed in the present article.
The commodity to be
tested imposes a number of limitations, and these must be taken into account
considering the use
of any meter. Perhaps the best way to
do this is to answer questions such as the
First, is the
chemical nature or any normal pre-treatment of the produce likely to interfere
with the use of
For instance, meters measuring electrical
conductivity may not be suitable for produce, like
will become highly conductive when damp.
Again, for commodities like dried egg or milk,
a heat-drying meter
may not be suitable.
Second, is the
moisture content to be measured outside the range for which the meter is
example, very few
electrical meters are known to be suitable for a product like made-tea whose
content is normally
required to be below 5 per cent, that is outside the range of moisture contents
electrical meters are calibrated.
Third, is the
milling property of the produce incompatible with the effective use of the
like macadamia nuts, palm kernels and copra are not easily ground, while others
like cashew nuts
(not the kernels) are simply not amenable to grinding.
Fourth, are the unit
size and shape of the produce likely to affect the efficient use of the
construction of the
meter may be such that it cannot be pushed into floury or powdery produce
measurement of moisture. Again, larger
products like cocoa beans, unshelled groundnuts,
cashew nuts and
pieces of illipe nuts (Shorea spp.) will present packing problems with some
If the answer to
each of the above questions is an unqualified `No', then the meter may be
suitable for the
product. But a `Yes' answer can make
all the difference between a meter being chosen
In such a case, steps should be taken to see
what, if anything, has been done to solve the
problem, either by
the manufacturer or by someone else.
Nature of the
Situation Needing a Moisture Meter
In an article of
this kind, it is not easy, even if it is possible, to cover all the situations
where the use
of a moisture meter
may be desired. However, such
situations are likely to fall into one or the other of
Knowing whether grain is at the right stage for harvesting.
The processing, (eg drying or milling), of foodstuffs.
Bulking or packaging produce for storage.
Commercial transaction, where moisture content is part of the basis for
Produce Inspection Service.
All the above
situations require moisture meters which are not fragile, which are
acceptable for the particular purpose, and whose performance is little affected
by the operating
conditions of space,
temperature, pressure, light, dust or wind.
They also require, to a greater or
meters that are simple to operate, portable and capable of taking remote
probe-electrodes, or stem hygrometers.
The purpose for
which the use of a meter is usually contemplated is two-fold:
to increase or improve
is, the flow of goods and services), and to ensure economical operations.
Productivity can be
improved by employing a meter which can give results rapidly; a meter for which
facilities for servicing and/or calibration are easily available; a meter which
does not depend
upon sources of
operating power that run out, break down, or become short in supply (eg
paraffin and other fuel).
Economy of operation
implies keeping down to the minimum both capital and operating costs, and/or
return to unit cost. Additionally, the
wider the range of commodities that a meter can test,
the more economical
will be its use. Likewise, the less
destructive a test is, the less will be the
incidental loss to
production, caused by the use of a meter.
Although this kind of loss may appear small,
it must be realised
that its magnitude will depend on how much produce is damaged at each test, and
many times such
tests are carried out on a given product.
It should be clear
from these discussions that very few meters, if any, can win the top position
conceivable area of
consideration, and that there is no magic formula for choosing a meter.
But where a
choice has to be
made, the final responsibility for it must be that of the buyer.
He must have a
knowledge of the commodity to be tested and the accuracy required of a
its moisture content
the availability of the meter, and the cost of operating it; the conditions
the meter will be
operated: the ease of obtaining spares
and facilities for servicing or calibrating the
the type of power supply required and
available. And when a provisional
choice has been made, it
is often advisable
to obtain the meter on loan for trial before buying.
The Quicktest grain moisture tester.
[/I]Report nat. Inst. agric. Engng, No. 83
(Nov.), 5 pp.
Farm grain drying and storage.
[/I]Min. Agric. Fisheries and Food, Bull.,
No. 149, 123-129.
BANNER, E H W.
1958. Electronic measuring
Chapman and Hall, 2nd edn, revised
xi, 496 pp.
LEFKOVITCH, L P and
PIXTON, S W. 1967. Calibrating moisture
meters. J. stored. Prod. Res., 3 (2),
MACKAY, P J.
1967. The measurement of moisture
content. Trop. stored Prod. Inf., (14),
PANDE, A and PANDE,
C S. 1962. Physical methods of moisture
measurement. Part 1:
Instrum. Pract., 16(7), 896-903.
PANDE, A and PANDE,
C S. 1962. Physical methods of moisture
measurement. Part 2:
ultrasonic, microwave and electrolytic
methods. Instrum. Pract., 16(8),
PIXTON, S W.
1967. Moisture content - its
significance and measurement in stored products.
Prod. Res., 3(1), 35-47.
STEVENS, G N.
1968. The measurement of grain moisture
content by rapid methods. Tech. Note
Grown Cereals Auth. No. 5, 3 pp.
WARNER, M G R and
HARRIES, G O. 1956. An investigation
into the performance of five typical rapid
methods of measuring the moisture content
of grain. Report nat. Inst. agric.
Engng, No. 46, (Mar.),
ZELENY, L and HUNT,
W H. 1962. Moisture measurement in
grain. For presentation at the 1962
Meeting of the Amer. Soc. Agric.
Engineers, Chicago, Illinois, Dec. 11-14.
Paper No. 62-926, 32 pp.
(Details from the authors:
Standardisation and Testing Branch, Grain
Division, Agric. Marketing
Service, USDA, Agric. Research Centre,
Details of some available proprietary moisture meters(1)
principles Power supply:
+ Under 1 min (Within % MC)
* Under 50 [pounds]
Self-generating ++ 1-5 min
** 50 [pounds] - 100
+++ over 5 min
*** Over 100 [pounds]
N None required
Thomas Ashworth & Co Ltd
23014Y, Stockholm 23
Cenco Instrumenten Mij, n.v.
Konijnenberg 40, Post Box 336
International Lab-Line Plaza
& Bloomingdale Aves,
Melrose Park, Illinois, USA
ts Crop Tester
2 Block Street, Bath
Townson & Mercer Ltd
CR9, 4EG, England
ELECTRICAL CONDUCTIVITY (Ec)
KPM Aqua Boy
K.P. Mundinger GmbH
D-7253 Renningen, W. Germany
Burrows Equipment Co
1316 Sherman Avenue
Safe Crop Moisture
explained on p. 28.
Table I (contd)
principles Power supply:
+ Under 1 min (Within %
MC) * Under 50 [pounds]
Self-generating ++ 1-5 min
** 50 [pounds] - 100
+++ over 5 min
*** Over 100 [pounds]
N None required
ELECTRICAL CONDUCTIVITY (Ec) (contd)
Agil Moisture Meter
1.0 - 2.0 *
Agil Ltd, Nicholson
Maidenhead, Berks, England
Hart Moisture Meter
Hart Moisture Meters,
400 Bayview Ave, Amityville
N.Y. 11701, USA
Coe's (Derby) Ltd
Thirsk Place, Ascot Drive
Derby, D'E2 8JL, England
Field House Lane
Scottish Mechanical Light
42-44 Waggon Road, Ayr
Siemens (UK) Ltd
Grt West House, Grt West Rd
Brentford, Middx, England
DIELECTRIC CONSTANT (Ed)
A/S N. Foss Electric
39 Roskildevej, 3400
Table I (contd)
principles Power supply:
+ Under 1 min
(Within % MC) * Under 50
++ 1 -5 min
** 50 [pounds] - 100 [pounds]
+++ over 5 min
*** Over 100 [pounds]
N None required
DIELECTRIC CONSTANT (Ed) (contd)
27 Stewart Avenue
Shepperton, Middx, England
1316 Sherman Ave, Evanston
Paul Lippke K.G. 545 Neuwied
PO Box 1760, Germany
* OY Fima Ltd,
A/S N. Foss Electric
39 Roskildevej, 3400
de la Radio
236 Chemin des Vitarelles
Seedburo Equipment Co
West Jackson Boulevard
Chicago, Illinois 60606 USA
Dole 300 Moisture
** Eaton Yale
& Towne Inc
Dole Division, 191 E North
Avenue, Carol Stream
Illinois 60187, USA
Meter Model 919
Table I (contd)
principles Power supply:
+ Under 1 min (Within % MC)
* Under 50 [pounds]
Self-generating ++ 1-5 min
** 50 [pounds] - 100
+++ over 5 min,
*** Over 100 [pounds]
N None required
+ 0.5 - 1.0
E J Chapman & Co Ltd
Martley, Worcester, England
Compagne des Compteurs (GB)
Ltd, Terminal House
Hyb 24, Hyb 25
Grosvenor Gdns, London SW1
Hyb 42, Hyb 43
INTER-GRANULAR RH (H)
Abrax Inc, 179/15H Jamaica
New York 11432, USA
Models 1 and 2
10/11 Gamage Building
All the information given in this table has come from the manufacturers
- Data not available
NB The exclusion of an instrument from
this table does not necessarily
imply the author's disapproval of
its use with agricultural produce.
WORKING PAPER ON THE
VOLUNTEER ROLE IN GRAIN
working paper was originally presented at a regional
seminar held in Cotonou, Benin, West Africa, in 1974.
The seminar was
sponsored by the International Secretariat of Voluntary
Services, the UN
Food and Agriculture Organization, and the
U.S. Agency for
purpose was to encourage the initiation of farmer-oriented
programs through the sharing of practical information
experiences. It was attended by over
100 participants from
in Africa, Europe, and North America. A
was published, by
the German Agency for Technical Cooperation Ltd.,
which includes all
working papers, discussions (summarized), and construction
plans for various
silo and dryer models reviewed during the
Several of the modified plans presented in
this manual are
included in the
seminar report. It is available from
the seminar secretary,
Dichter. His address is:
David Dichter and Associates,
Assistance Programmes, 9 rue de Vermont, 1202 Geneva, Switzerland.
WEST AFRICAN SEMINAR
ON THE VOLUNTEER ROLE IN FARM
AND VILLAGE-LEVEL GRAIN STORAGE
DECEMBER 13-23, 1974
WORKING PAPER No. 1
PROBLEMS RELATED TO
POPULARIZING NEW FARM-LEVEL
GRAIN STORAGE TECHNOLOGY
United States Peace Corps
Volunteers to Dahomey (Benin)
of Rural Development
Since 1967, the Agriculture Service of
Dahomey and the United
States Peace Corps
have collaborated in creating, implementing and
farm-level grain storage program in southern Dahomey.
result of this joint
program is the actual construction of over two
hundred and fifty
individual storage units. Another
seven years of
cumulative experience in working through some of
day-to-day problems of popularizing new farm-level grain
technology. This shared experience by
two organizations, one
a governmental agency
and the other an international volunteer agency,
forms the basis for
The authors see the primary purpose of
this paper as a presentation
of some of the major
considerations in the planning and
establishment of a
farm-level grain storage program. Of
importance is a
brief history, attached as an appendix, of the
collaboration of the
Agriculture Service and the Peace Corps in
While the authors' program is limited
to Dahomey and primarily
one type of storage
facility; it is hoped that their practical
experience will be
of benefit to others initiating similar programs,
regardless of the
storage method adopted. The paper is
nor a "how-to-do-it" guide to popularizing new
techniques in grain
storage. Rather, it is a brief
examples based on the author's experience of five
major areas of
concern in planning a new grain storage project:
Assessment of the problem
Choice of the improved method to popularize
Stimulating interest in improved storage methods
The extension and integration of the project into the
"Construction Manual for the 4.5 Ton and 2.5 Ton Cement Silo
and the Mud Walled Grain Dryer" by
U.S. Peace Corps Volunteers,
October 27, 1974.
Assessment of the Problem
The initial phase in the planning of a
project to improve grain
is an analysis of the problem from the point of
view of the farmer
in the particular locality to be served.
ingredient. Any program must be based
upon realities as seen
by the farmer who
will be storing his grain.
In Dahomey, the traditional
corn-growing farmer lives in a
small village and
annually cultivates up to 3 hectares (7 - 1/2 acres)
His annual yield with two growing seasons
could be estimated
kg/hectare or a total of 1,800-2,400 kg.
This is classic
probably not unlike that of most corn-growing
farmers in the
Traditional storage methods.
Initially in the consideration,
choice and planning
of an improved storage program it is advisable
to analyze local traditional
methods in order to (1) understand their
therefore the need for improved techniques and (2)
possible simple, yet effective, improvements.
minor and effective
changes to existing methods of storage are easier
to popularize than
the introduction of complex and costly alternatives.
For example, perhaps
improved sealing of traditional granaries or
program of insecticide treatment could have significant
At any rate, the important point is to
think about the traditional
methods of storage
from the farmer's viewpoint. Does he
find that the
are inefficient? Does the rapid rate of
it impossible to store grain over a long period
of time with his
traditional method? Do mold growth and
What about rodents and birds?
How much grain does he actually
lose with his
traditional methods of storage?
Market Price Realities.
As a practical matter, farmers will not
be inclined to
change their traditional storage methods unless there
will be sufficient
financial returns from whatever additional labor,
time or cash inputs
are required by the improved storage techniques.
economics of the improved techniques as affecting subsistence
farmers must be
Local market price information is
needed. What are the prices
of grain at harvest
time and at the yearly high? Also, does
have large financial
demands at harvest time? What are his
Does he normally have to sell his grain
before prices have
started to reach
their seasonal high? How much
fluctuation is there in
the price on the
local market? Are there other more
he can reach
easily? Is transportation of his crops
to the market expensive
There are other economic and market
factors to consider. For
traditionally, grain in Dahomey is sold in markets by volume
rather than by
weight. This could work against the
adoption of improved
methods. The improved quality of
well-stored grain, for instance,
could bring few
benefits if the farmer not using improved methods can mix
a large proportion
of his damaged corn with good grain and thus sell it
at the same price as
Similarly, are grain prices keeping
pace with inflationary price
rise in the cost of
the new storage techniques? Also,
prices, for example,
can reduce potential profits. In short,
the economies, that
is, the practical benefits of a new method, must be
thought through from
the farmer's standpoint or, it may fail to be
accepted because of
simple economic realities.
Social Customs and Traditions.
Similarly, local customs and
traditions should be
carefully studied from the farmers viewpoint to see
what impact they
might have on the introduction of a particular storage
The use of insecticides, for example, may
If farmers are used to leaving their maize
storage, will they
resist? Will insecticide-treated grain
have a changed
taste or odor?
Is treated grain acceptable by the farmer
for his own
Is it acceptable for sale locally?
Have there been any
bad experiences in
the locality as a result of the misuse of insecticides?
Another example of the importance of
social customs is the farmer's
centralization of storage facilities.
Does the farmer
a granary in his field and leave the crops stored
needed? Would a central storage silo
cause him transportation
Will he resist co-operative storing because
he doesn't want
his neighbor to know
how much he has produced? Social
factors such as
these can affect the
success of a new storage program.
Having analyzed the problems from the
point of view of the farmer,
the planning agency
or organization must decide upon the scope of the
program it hopes to
introduce and to what extent it can support the program.
The providing of new information and
training and support
for the introduction of improved storage methods
considerable personnel. Does the agency
have sufficient manpower?
Will the personnel need
training in the new techniques? Will
be needed? To whom will volunteers be
What will their role
be in relation to the permanent extension personnel?
coordination be arranged? Is the
organizing agency willing to
personnel to assure the success of the program?
therefore, are extremely important in planning a new program.
The supply of necessary materials must be
assured as well.
To what extent is the project dependent upon
materials which are
influenced by outside forces, ie., regional or world
inflation. Cement, insecticides, tin
sheeting, re-rod, sand,
wood ---- are they readily available? Who
assuring the supply of needed materials?
is that person or
agency? How reliable is the
supply? Lack of critical
items when needed
will undermine the farmer's confidence in the program.
Are local transportation facilities
adequate for the
needs of the program? If they are not,
vehicle support must
be made. In such a case, decisions must
be made as
to the use of the
vehicles before precedents are set. If
dependent on a
project to transport their harvests, this may prevent the
development of local
transport and cause difficulties when the project
can no longer
continue such support.
Marketing success of grains stored using
will influence the rapidity with which those methods
For example, if local market prices do not
as greatly as those
in urban centers, the sponsoring agency may want
to consider the
planning and support of organized transportation for
The program should consider the available
and look for improvements to enhance the value of the
techniques. For example, the sponsoring
agency may want
to reward farmers for
the improved quality of their grain by introducing
some system of
quality grading or sale by weight to help popularize their
The above brief summary includes some
of the major factors an
agency must evaluate
in deciding at what level it is willing to and
participating in a program for new grain storage techniques.
Having thus considered the problem, one
is better prepared to choose
the particular means
of improving storage which is best suited for the new
Choice of the Improved Method to Popularize
The choice of an improved storage
technique for popularization
should result from
an analysis of the existing problems.
economic factor will
weigh very heavily. In dealing with
farmers with very
limited cash resources, the total cost of construction,
utilization of a new technique must be measured
the effectiveness and practical benefit to the farmer.
This type of
calculation generally requires time for both study and testing
of the new method,
two factors which are important to the process of choosing
a storage technique.
The importance of scientific testing cannot
Such analysis, before introducing the new
to the farmer, can
avoid many problems.
Scientific testing lends authenticity
and permits the sponsoring
agency to defend
confidently such factors as reliability and efficiency.
For example, the Institute
of Research for Tropical Agriculture (IRAT),
in Dahomey, has
greatly advanced storage techniques in that country by
its testing of many
storage methods, among them; local granaries with
insecticides, cribs, artificial dryers, cement stave and metal
The results of these experiments have
produced information important
to the planning,
choice and policy of grain storage programs in Dahomey.
Testing, therefore, is an important
step in choosing a particular
method of improved
Less formal, but equally revealing, is field
For example, field trials can help to verify
local materials as substitutes for more obvious and costly
Field tests uncover hidden problems and
They can indicate the level of farmer
interest in the proposed
An example of the value of field tests
in Dahomey was demonstrated
when they revealed
that storage in butyl bags was impractical because common
bursting, and rats or sharp objects easily pierced
the bag destroying
its air tightness. In effect, the field
a new technique
provides a kind of market sampling of the locality before
The use of permanent
extension agents or Volunteers in performing field
tests can be
effective. In Dahomey, for example,
Peace Corps Volunteers
field experimentation in the early years that resulted
in much practical
information essential to developing the grain storage
Such field experiments must be cearly
described as such to farmers
to avoid false
impressions and to permit adjustments of the program.
protected, one can
obtain valuable information pertaining to such additional
questions as (1) how
much training time and supervision is necessary to
construction and/or proper use? (2) can
the farmer maintain
himself? (3) are special tools
required? (4) will the
extension system support the new technique?
The final choice of a particular
storage method to popularize will
be a balance of many
of the factors previously discussed in the context
of local conditions.
To help the reader assess the various grain
during the seminar, a "table of consideration" is attached
to aid in one's
analysis. Participants can fill in any
they feel is
pertinent and valuable to their specific purposes.
Methods of Financing the Introduction of New
The organization of the financial
aspects of a new program of improved
techniques is essential to the smooth start of the program.
There are several
types of financing available from which to choose, among
which are included:
Direct cash investment by participating farmer
Direct cash investment by participating
Cash payment for any improved storage
technique is the simplest
and most direct
method of financing. It requires a
minimum of administrative,
coordinating burdens for the sponsoring agency.
cash programs using
the personal financial resources of the farmer
can be the method of
financing which gives the widest and fastest possible
popularization of a
program, providing that they are relatively inexpensive
and accessible to
In countries with an average annual her
capita income of less than
$100, such as
Dahomey, many methods of storage which are relatively low-cost
will still be beyond
the means of the average small farmer.
case, high cash
requirements can severely limit the scope of a program
and the speed of its
If the cost of the new technique is too
high, the benefits derived
improvements may be concentrated in the hands of farmers at the
highest income level
or even with merchants and civil servants who are
quick to see the
monetary advantages of improved storage methods.
Thus, other methods of financing will
have to be considered if the
average farmer is to
participate in improved storage programs.
as a result of his
use of improved methods, his increased income may permit
him to assume more
financial responsibility for additional improvements.
Credit financing can increase the
potential availability of improved
storage methods to
the low-income farmer.
Selection of credit recipients is an
important consideration. If
the project uses
financial criteria similar to those used for bank loans,
most small farmers
will not have sufficient resources or collateral to
In order to make credit available to those
who need it
risking a low rate of repayment, it may be necessary to allow
repayment of loans
in kind or make provisions for a commercialization
program for the
To participate in a
credit program, a farmer should be asked to show his
degree of interest
in the project, beforehand. This can be
the requirement of a
cash advance or the supplying of specific materials
The System of repayment of the credit loan
should be well-planned
before the program
begins. Provisions should be made for
that a certain
proportion of the loans will not be repaid sometimes due
beyond his control, such as crop failure.
The terms and
requirements of the
credit program must be clearly explained to all farmer
participants and to
all extension personnel to assure that all parties
the responsibilities being assumed.
Another way of financing a program of
improved grain storage
techniques is by
price support contributions by the sponsoring agency.
This is a form of
gift but it is for the purpose of underwriting the
For example, it might involve granting a
portion of the cash
construction materials or transportation expenses, the remainder
being paid for by
the interested farmer or cooperative.
Price supports can provide a valuable
alternative to cash and
especially when there are rapid increases in the prices
of building materials
or insecticides without equivalent increases in
the prices that
farmers receive for their produce.
Price supports used
in conjunction with
a cash program can serve to avoid the repayment problems
inherent in credit,
thus decreasing the administrative burdens of the
Un-repayed credit becomes a gift.
If a high percentage of reimbursement
cannot be assured by
a credit program, it might be better to distribute
financial resources through the use of price supports.
would make it
possible to extend the benefits of the program to more people.
A price support program, while limited
by the resources available,
has many of the
advantages of a cash program. The
project personnel has a
smaller and less
complicated administrative work-load than a credit program.
Another advantage is
that the interest of the farmer is assured by his cash
Grants provide a means of having
programs quickly accepted by
farmers; their scope
is limited only by the financial capabilities of the
agency. However, grants can present
problems to the long-term
development of a
program. Once the project funds have
been exhausted for
grant financing, it
may be difficult to convince farmers to pay their own
money for what
others have been given free. In this
case, there may be
a lag in
popularization while farmers wait to assure themselves that no
further gifts will
There is another problem that may
result from the donation of a
Since the investment by the farmer is
minimal, his interest in the
upkeep and proper
use of the items received may also be minimal.
If grants for the total cost of the
storage method are to be given
participants, better results may be assured by careful selection
thorough explanation of the practical advantages and use of
the storage method,
followed by continued supervision in its proper use.
Stimulating Interest in Improved Storage
There are many methods of popularizing
a new storage technique or
interest in it. The manner in which it
is done can directly
affect the number of
farmers who will choose to try the new technique.
It is best that the program be completely
planned before commencing
popularization at the farmer level, in order to avoid confusion
For example, project field agents should be
trained and fully
informed about the
program before they begin discussing it with farmers.
The storage method
should have been tested. The financial
should be settled
and agreed upon. Transportation
problems should be
Provisions should be made for the rapid
acceptance and expansion
of the program.
Once all these matters are prepared, than
Demonstration of improved storage
methods can be very effective in
to adopt the new method for themselves.
models should be
highly visible and built to attract a lot of attention.
for demonstration sites are: near the
home of an individual
farmer, at farmers'
cooperatives, at agricultural youth clubs, at agricultural
expositions or on
publicly owned land.
Important considerations in attracting
the farmers' attention are:
Is the location
easily seen? Is adequate, easily
If it is built for an individual farmer, is
Will he use the
site? Are there local personnel
available who can explain
Will the site be attractive and
On Farm Demonstrations
Because of some traditional farmers'
reluctance to adopt new methods,
demonstration sites may need to be built on a total gift or
basis, perhaps with a guarantee to reimburse any losses
in the event of
failure. However, when the
demonstration site is installed
as a gift,
recipients may have little stake in its success.
purpose of a demonstration
site is to spread the knowledge of good results,
special care should
be taken that such sites are well chosen to reduce problems
of mis-use or
abandonment. It is a good idea for the
selection of farmers
sites to be done with the aid of local agricultural extension
authorities. Additionally, close
supervision and careful
storage techniques will held to assure good results and positive
The high visibility offered by
agricultural fairs presents an
opportunity for display, explanation and discussion of demonstration
An explanation in the local language by a
convinced of the
method through personal experience and success can greatly
increase the impact
of an agricultural fair demonstration.
is increased by
handing out simple flyers which briefly explain the storage
method and give
names and addresses to contact for more detailed information
Demonstration Sites on Public Lands
Sites near market places, health
clinics or local agricultural
offices can be very
effective demonstration locations.
Since this type
of site generally
has no single owner or person responsible for its
should be made in its planning to provide for
continued and proper
use because an unused storage unit can be a bad
Increased credibility and effectiveness can
by assistance of
local agricultural extension agents in demonstration site
information dissemination and by inviting local farmers
to participate in
all aspects of its use. Whenever
farmers to a demonstration site can increase its impact.
Use of Radio and Newspapers
For more widespread popularization
purposes, agricultural radio
newspapers can be used. Since these
methods lack the visual
opportunity for questions provided by actual demonstration sites,
explanations must be
clearly and convincingly focused at the level of
knowledge of the
prospective users, preferably in the local language or
self-explanatory diagrams and pictures.
With all of the above methods for creating
information dissemination, emphasis should be placed
on the practical
benefit of the new storage method and all popularization
efforts should be
designed for high visibility and comprehension at the
level of the farmers
for whom the project is aimed.
Integration into the Local Infrastructure
A grain storage program can have a more
lasting and broader impact
if it is closely
integrated with agricultural extension services, farmers'
craftmen and the local marketing structure.
such integration can
reduce the program's organizational and logistical
For example, the management of insecticide
might be turned over
to merchants' or farmers' organizations.
once trained in
storage construction skills, can take over further training
apprenticeship of younger craftsmen.
Agricultural agents can supervise
and storage. Involvement at all levels
of the agricultural,
economic and social
sectors will help bring about an integration
results in adaptation of the storage method.
Coordination with other related
projects can also extend the long-range
effect of a grain
storage project. For example, a broader
base might be gained
by joining forces with grain commercialization programs
production projects which encourage the use of fertilizers,
and/or animal traction. This type of
coordination can provide
benefits for other sectors of activity as well.
To achieve real and continued
integration, one of the project's
conscious goals must
be just that, integration. Contact
regular meetings or frequent interchange can held
communication going and to facilitate cooperation.
thorough training will increase the value of the project
contribution toward integration.
can be held "on
site" for direct experience or, in the case of large groups,
courses can be incorporated at local training institutes
Given the temporary nature of
third-party developmental aid, a
project relying on
this type of support cannot expect to have long-term
integration into existing infrastructures is not undertaken.
integration begins, the less is the risk caused by the eventual
or sudden loss of
outside project support, local participation and local
Brief History of the Grain
Program of the Agriculture
of Dahomey and the U. S. Peace
It was in 1967 that the Agriculture Service
of Dahomey under the
Ministry of Rural
Development first asked for U.S. Peace Corps volunteers
to assist it in
implementing a new program of grain conservation at the
farm level in
southern Dahomey. Problems with grain
storage had always
been acute in
The vast majority of maize produced
annually in Dahomey is grown
in the southern half
of the country where there is constantly high
temperatures which foster rotting as well as the multiplication
insects. The traditional method of
southern Dahomey is
in loosely-woven palm thatched granaries raised on
The only real protection against attack by
insects is offered
by the husk on each ear of maize, resulting in 30%
average loss of the
300,000 tons approximate annual production.
estimated value of
maize lost annually to the combined effects of insects,
rodents and rot is a
minimum of 600,000,000 CFA (about $3million).
The idea behind the original request was
to introduce to individual
farmers the use of
the insecticide, Phostoxin, with steel drums and butyl
sacks furnished by
the Office of Agricultural Commercialization of Dahomey
under a grant by US AID.
Thus, the initial impetus to the
project was aimed at popularizing
a new storage
technique at the farm level. It also
entailed assessment of
of storage and experimentation with a variety of potential
improved methods of
storage. One of these methods was the
cement stave silo,
adapted from larger
models used in the United States, and the mud-walled
developed at Ibadan, Nigeria, and adopted by the Institute of
Research of Tropical
Agriculture (I.R.A.T.) at Niaouli, Dahomey.
Since the process of artificial drying
and storage in a new type
of silo was
experimental, and the results could not be guaranteed, the
majority of the
expenses of constructing the first units for individual
pilot farmers were
paid for by the U.S. Embassy Self-Help Fund.
Over the first few years, the
Agricultural Service and the Volunteers
modifications in the design of the silos and dryers.
this period of
experimentation Dahomean Agricultural extension agents and
offered their help and advice.
Cumulative results of field
testing did indicate
to the Agricultural Service and the Peace Corps that
the Cement stave
silo merited carefully controlled scientific experimentation
to determine its
reliability of performance.
By 1971, it was clear that (1) farmers
in Southern Dahomey were
ready to accept new
methods of storing corn, (2) the earthen dryer was
effective and had
potential for popularization, and (3) there were two
types of silos --
cement stave and sheet metal (the latter developed by
appeared promising for farm level storage.
At this point, it was decided by the
Agricultural Service, the
Peace Corps and
I.R.A.T. that controlled tests should be performed.
experiment was installed at the I.R.A.T. station at Niaouli.
Twelve cement stave
silos and twelve sheet metal silos were built and placed
under a large
shelter. The silos were filled at the
end of October, 1971,
and emptied in June 1972. They were
then refilled with
new maize in
November, 1972, similarly tested and emptied in May, 1973.
The results of these
trials demonstrated that both types of silos, if
insecticide, store maize extremely well.
It was determined
that maize dried to
a moisture content of 12% and treated with any of a
insecticides could be stored in cement stave silos for at least
six months with
average losses of not more than 3 percent.
During this time, volunteers had been
working with local agricultural
popularize and build silos and dryers for interested farmers
who could afford the
units which had an average cost of $70-$80 (without
expensive tin roofed
shelter). It was after the I.R.A.T.
tests that the
director of the
Dahomean Agricultural Service decided to officially adopt
this system, and the
National Cereals Commission of Dahomey committed 5 millio
CFA ($20,000) for
the credit construction of 100 storage units for individual
consisting of a 4.5 ton cement stave silo, an earthen dryer,
and a tin-roofed
shelter. The first ten units were built
in the region
of Sakete, under the
supervision of a technical agent of the Agricultural
Service and a Peace
Corps Volunteer. These completed units
accepted by the Minister
of Rural Development and Cooperative Action in
June, 1974, and work
has been authorized on construction of another twenty
in the three
southern provinces of Dahomey.
The National Cereals Commission has
established criteria for the
100 farmers who are
to receive this credit. The
be a farmer
cultivate at least two hectares (5 acres) of maize per year
reside in the district where the silo is to be built
be recognized by local agricultural agents as a progressive
and cooperative individual
be willing to sign a contract for the repayment of the loan
make a 10,000 CFA ($40) cash advance as an indication of
The loan is to be paid off in six equal
annual payments at 2%
Payment can be made in cash or the
equivalent value of maize
at a pre-determined
value of 25 cfa/kg (the average price of maize at the
time of harvest has
been from 6 to 10 cfa/kg).
Over the years, the collaboration has
grown between the Peace Corps
and the Agricultural
Service and particularly its Division of Crop Protection
which has a
supervisory role with respect to the volunteers.
Requests for and
assignment of volunteers is handled through these offices.
A volunteer with
experience in the program in Dahomey has traditionally
been designated as
"Coordinator" by the Dahomean officials and Peace
Corps staff, and he
acts as a liaison between the grain storage volunteers
in the field, the
Peace Corps staff in Cotonou, and the government agricultural
Porto-Novo. The Peace Corps, besides
helped find outside funding for program related projects.
The information in
this manual is not and can not be complete.
presented here cannot be immediately applicable or appropriate
to all regions or to
every storage need. You may well
assistance in adapting these materials and others
to your grain
storage situation. Some of that help
can come from
books; much, from
organizations and people.
Products Institute (TPI) may already be a familiar name
This agency does a great deal to gather and
worldwide on grain
and grain storage problems. Materials
the TPI library have
been of great value in the preparation of this
Peace Corps and VITA
are grateful to TPI for its permission to reprint
bibliography of materials on the various aspects of farm-level
Crop storage bibliography
(with particular reference to
the storage of durable
agricultural produce in
and sub-tropical countries)
Mrs. S.M. Blatchford and A.J.
has been produced by the Tropical Products Institute, a British
organization which helps developing countries to derive greater benef its
from their renewable
Reproduction of this
bibliography, in whole or in part, is gladly permitted provided that
is given to the Tropical Products Institute, Foreign and
(Overseas Development Administration), and to the authors.
Requests for further
information on this subject should be addressed to:
Slough SL3 7HL
BULLETINS, SPECIAL REPORTS
N O T E S
attempts to bring together a selection of the more important publications
tropical crop storage; it clearly cannot be exhaustive.
Where possible, the
prices (at time of publication) and addresses are given for obtaining
here, excluding scientific papers. A
list of the most common addresses
101-113. Pentonville Road, London, N.1.
AGRICULTURE, FISHERIES and FOOD:
FOOD & AGRICULTURE ORGANIZATION:
Sales Section, Via delle Terme di Caracalla, 00100 Rome, Italy.
DEPARTMENT OF AGRICULTURE:
Documents, U.S. Government Printing Office, Washington D.C. 20402, U.S.A
ANDERSON, J.A. and ALCOCK,
A. W. (Eds).
Storage of cereal grains and their
products. St. Paul, Minn:
Cereal Chem., 1954, ix + 515
pp. (Out of print:
obtainable from Univ.
Microfilms, Ann Arbor, Mich.,
price 10.00 [pounds]. Currently under
Insects and hygiene.
The biology and control of insect pests of
and domestic importance.
Methuen and Co., 1966, 2nd rev.
edn, xi + 467 pp.
Price 5.00 [pounds].
and KAUFMANN, H.H.
The role of fungi in quality loss.
Univ. Minnesota Press, 1969,
vii + 153 pp. Price $6.50.
Pests of stored grain and grain products.
Minneapolis, Minn: Burgess
Publg Co., 1963, rev. edn, 2 + i +
318 pp. (Out of print).
Pests of stored products.
Hutchinson (The Rentokil Library),
1966, 234 pp.
Price 2.10 [pounds].
Storage of grain.
Izdatel'stva `Kolos', 1966, 3rd edn, 406 pp.
(Translated into English by
Keane, D.M. and edited by Kent, N.L. &
Freeman, J.A. Boston Spa:
natn. Lending Libr., 1969, 3 volumes, 244,
287 & 307 pp.
Price 1.25 [pounds] per vol., 3.75 [pounds]
BULLETIN OF GRAIN
Foodgrain Technologists' Research Association of
Price $3.00 per annum.
JOURNAL OF STORED
Pergamon Press. Price 12.00
[pounds] per annum.
Bulletin of the Tropical Stored Products
(Enquiries to the Tropical Stored Products
Centre, (TPI), London Road,
Slough SL3 7HL, Bucks).
TECHNOLOGICAL RESEARCH INSTITUTE.
Annual reports of the C.F.T.R.I., Mysore - 2, India.
Reports of the Infestation
Control Laboratory (Ministry of Agriculture,
Fisheries & Food).
PRODUCTS RESEARCH INSTITUTE.
Annual reports of the Nigerian
Stored Products Research Institute, Federal
Ministry of Trade.
Fed. Minist. Inform., Printing
Annual reports of the Pest Infestation Laboratory (Agricultural
Annual reports (up to and
including 1967) and then Biennial reports of the
Tropical Products Institute, (Overseas Development
(Enquiries to the Scientific Secretariat,
Institute, 56-62 Gray's Inn
Road, London WC1X 8LU).
TROPICAL STORED PRODUCTS
CENTRE: MINISTRY OF OVERSEAS
Tropical Stored Products Centre.
A Report on the work 1965 - 1966.
(The work of the Centre prior
to 1965 was reported as part of the
Annual Report `Pest
Infestation Research'; from July 1967 it forms a part
of the Annual and Biennial
Reports of the Tropical Products Institute.
Enquiries to the Tropical
Stored Products Centre, (TPI), London Road,
Slough SL3 7HL, Bucks).
Bulletins, Special Reports
Fumigation with methyl bromide under
gas-proof sheets. Dep. Sci. Ind.
Res., Pest Infest. Res. Bull. No.
HMSO, 1959, 2nd edn, ii +
Price 22 1/2p.
COTTERELL, G.S. and
Insect infestation of stored food
products in Nigeria. (Report of a
1948 - 50, and of control
measures adopted). Colonial Res. Publn
HMSO, 1952, 40 pp.
(Ed). Preservation of grains in
storage. Papers presented at the
meeting on infestation of
foodstuffs, London, 5 - 12 Aug., 1947.
Fd. Agric. Org. agric. Stud. No. 2, 1948,
174 pp. Price $1.50.
Control of pests in stored agricultural
products with special reference to
Report of a survey in North and South America and certain
countries in 1954 and
1955. Org. eur. econ. Coop., eur.
Project No. 212, Feb.
OEEC, 1958, 169 pp. Price
(OEEC Dist. & Sales Serv.,
33 Rue de Franqueville, Paris 16e and overseas
Suggested guide for the use of
insecticides to control insects affecting crops,
livestock, households, stored
products, forests and forest products.
Dep. Agric., agric. Res. Serv.,
agric. Handbk No. 331, 1968, rev. edn, xvi +
273 pp + 2 app.
Handling and storage of food grains in
tropical and sub-tropical areas. FAO
Dev. Paper No. 90.
Rome: UNFAO, 1970, xiv + 350 pp.
Price US $6 (2.40 [pounds]).
HINTON, H.E. and
Common insect pests of stored food
products. A guide to their
Econ. Ser. Brit. Museum (nat.
Hist.), No. 15. London: British Museum,
1963, 4th edn, vi + 61 pp.
Price 17 1/2p.
Aeration of grain in commercial storages. U.S. Dep. Agric.,
Mktg Res. Rep. No. 170, 1960
(revised and reprinted Sept. 1966), 46 pp.
Price 35 [cents].
The mites of stored food.
Tech. Bull. Minist. Agric. Fish. Fd, No. 9,
vi + 287 pp. London:
EUROPEAN AND MEDITERRANEAN PLANT PROTECTION
Report of the international conference
on the protection of stored products,
Lisbon 27 - 30 Nov. 1967.
EPPO Publications, Ser. A, No. 46-E. Paris:
EPPO, 1968, 171 pp. Price 1.65
[pounds]. (EPPO, 1 rue le Notre, Paris).
EUROPEAN AND MEDITERRANEAN PLANT PROTECTION
Report of the working party on Stored
Products of Tropical Origin (Hamburg,
5 - 6 Nov. 1968).
EPPO Publications, Ser. A, No. 51-E.
Paris: EPPO, 1969,
38 pp + 7 tables.
Price 50p. (EPPO, 1 rue le Notre, Paris).
EUROPEAN AND MEDITERRANEAN PLANT PROTECTION
Report of the Working Party on Stored
Products of Mediterranean Origin
(Lisbon, 13 - 14 March,
1969). EPPO Publications, Ser. A, No.
EPPO, 1970, 85 + xxx pp.
(EPPO, 1 rue le Notre, Paris).
JOUBERT, P.C. and DE
The toxicity of contact
insecticides to seed-infesting insects.
Series No. 6.
Tests with bromophos on
maize. S. Afr. Dep. Agric., tech.
Commun. No. 84. Pretoria:
Government Printer, 1968, 9 pp.
KAMEL, A.H. and
Protection of stored seeds in
Egypt. Bull. Minist. Agric. Egypt, Ext.
No. 295. Cairo:
General Organization for Government Printing
1958, 16 pp.
Evaluation of several formulations of
malathion as a protectant of grain
sorghum against insects - in small
bins. U.S. Dep. Agric., agric. Res.
Mktg Res. Rep. No. 828, 1969,
iv + 19 pp. Price 20 [cents].
Evaluation of malathion, diazinon, a
silica aerogel and a diatomaceous
earth as protectants on wheat
against lesser grain borer attack ... in small
U.S. Dep. Agric., agric. Res. Serv., Mktg
Res. Rep. No. 860, 1970,
iv + 12 pp.
LOCHNER, E.H.W. Safe
storage of food grains in the Republic of South Africa.
S. Afr. Dep.
Agric., tech. Serv., tech. Commun.
No. 13. Pretoria: Government Printer,
1963, ii + 45 pp.
Fumigation of maize in railway trucks in transit to the ports.
with English Summary).
S. Afr. Dep. Agric., tech. Serv., tech.
No. 25. Pretoria:
Government Printer, 1964, ii + 62 pp.
MARTIN, H.G., DIXON, W.B. and MOLLISON, D.W.
Prevention and control of infestation of stored grain by
insect pests and
Prepared jointly by the Storage and
Dept, Minist. Trade and Ind.)
and Plant Protection Division (Minist. Agric.
Govt Printer, 1961, iii + 57 pp.
Manual of fumigation for insect
control. F.A.0. agric. Studies, No. 79.
FAO, 1971, xii + 381 pp. Second edn, revised.
Price 2.80 [pounds].
(Gen. Ed). Pest control in
groundnuts. PANS Manual No. 2. London:
Overseas Dev., trop. Pestic. Res. H.Q. & Inf. Unit, 1967, iv
+ 138 pp.
(56-62 Gray's Inn Rd, London, WC1X8LU).
An investigation into storage problems of
rice in Sierra Leone. Colonial
Res. Studies, No.28.
HMSO, 1959, 52 pp.
Buildings for the storage of crops in warm
climates. Dep. sci. ind. Res.
Trop. Building Studies, No. 2.
London: HMSO, 1960, 24 pp. Price 22
Investigations into grain storage problems
in Nyasaland with special
reference to maize (Zea mays
L.). Colonial Res. Publn No. 21.
HMSO, 1957, 49 pp. Price 22
Meteorology and grain storage.
Tech. Note U.N. Wld met. Org., No. 101
(WMO No. 243 TP 133). Geneva:
Secretariat of World Meteorological
Organisation, 1969, xvi + 47
pp. Price 1.00 [pounds].
(Gen. Ed.). Pest control in rice.
PANS Manual No. 3. London:
Overseas Dev. trop. Pestic. Res.
H.Q. & Inf. Unit, 1970, ii + 270 pp.
Price 62 1/2p.
(56-62 Gray's Inn Rd, London WC1 X8LU).
FOOD AND AGRICULTURE ORGANIZATION.
Improved storage and its
contribution to world food supplies.
in `State of Food and
agriculture, 1968', pp 115 - 143. Rome:
1968, 205 pp. Price $5.75 or
FOOD AND AGRICULTURE ORGANIZATION.
Technical Report No. 1 of the Food Research
Unit, Accra, Ghana.
Prepared for the Government of Ghana by FAO
acting as executing agency for
the United Nations Development Programme,
based on the work of J.
Rawnsley. PL:SF/GHA 7.
ix + 89 pp + 7 app.
DEPARTMENT OF AGRICULTURE: AGRICULTURAL
SCIENCES BRANCH, STORED PRODUCTS INSECTS SECTION.
Stored grain pests.
U.S. Dep. Agric. Fmrs Bull. No. 1260, 1958,
46 pp. Price 25 [cents].
Mycotoxins in foodstuffs.
Proceedings of a symposium at Massachusetts
Inst. Technol., March 1964.
Mass. Inst. Technol.
Press, 1965, xii + 291 pp.
Price 3.75 [pounds].
Food storage manual.
(Prepared by the Tropical Stored Products
Ministry of Overseas
FAO, 1970, 3 vols, 820 pp.
BOOTH, C., HOLLIDAY,
P. and SUBRAMANIAN, C.V.
C.M.I. descriptions of pathogenic
fungi and bacteria. Set 22, sheets 211
Commonw. Mycol. Inst., 1969. Price 25p. (Commonw.
Mycol. Inst., Ferry Lane, Kew,
Methods for sampling
oilseeds. Br. Stand. No. 4146, 1967, 16
pp. Price 30p.
Methods of test for cereals and
pulses. Part 2.
Determination of moisture
content of cereals and cereal products (basic reference
method). Br. Stand.
No. 4317, Part 2, 1968, 12 pp.
Methods of test for cereals and
pulses. Part 4.
Determination of impurities
Br. Stand. No. 431 7, Part 4, 1968, 7
pp. Price 20p.
Methods for sampling cereals (as
grain). Br. Stand. No. 4510, 1969, 19
Methods for sampling pulses.
Br. Stand. No. 4511, 1969, 16 pp. Price 40p.
Recommended common names for
pesticides. Br. Stand. No. 1831, 1969,
4th rev., 107 pp.
Price 2.00 [pounds].
BRANDENBURG, N.R. and KLEIN, L.M.
Mechanical seed cleaning and
handling. U.S. Dep. Agric., agric. Res.
(in conj. w. Oregon agric.
Exp. Stn), agric. Handbk No. 354, 1968, 56 pp.
Price 55 [cents].
AGRICULTURE, FISHERIES and FOOD.
Fumigation with the liquid
fumigants carbon tetrachloride, ethylene
dichloride and ethylene
dibromide. Precautionary measures.
HMSO, 1966, rev. edn, i + 8
pp. Price 71/2p.
AGRICULTURE, FISHERIES and FOOD.
Heating of grain in store.
Minist. Agric. Fish. Fd, Adv. Leafl. No.
1968, rev., 6 pp.
Single copies free.
AGRICULTURE, FISHERIES and FOOD.
Insect pests in food stores.
Minist. Agric. Fish. Fd, Adv.`Leafl. No.
1968, rev., 8 pp.
Single copies free.
AGRICULTURE, FISHERIES and FOOD.
Fumigation with ethylene oxide.
Precautionary measures, 1969.
HMSO, 1969, 8 pp. Price 9p.
DEPARTMENT OF AGRICULTURE: AGRICULTURAL
AGRICULTURAL ENGINEERING RESEARCH DIVISION.
Guide lines for mold control in
high-moisture corn. U.S. Dep. Agric.,
Bull. No. 2238, 1969, rev., 16
pp. Price 10 [cents].
DEPARTMENT OF AGRICULTURE: AGRICULTURAL
QUALITY RESEARCH DIVISION.
Controlling insects in farm-stored
grain. U.S. Dep. Agric., Leaff. No.
1969, 8 pp. Price 10 [cents].
A full list of
papers published by staff of the Tropical Stored Products Centre is available
request from the
TSPC, (TPI), London Road, Slough SL3 7HL, Bucks).
AMARO, J.P. and
CANCELA DA FONSECA, J.P.
Panorama actual dos problemas
fitossanitarios dos produtos armazenados
(Comprehensive survey of phytosanitary
problems of stored
products in Africa).
Garcia de Orta, 5 (4), 675 - 699.
The chemical control of stored food
insect pests in Kenya. J. agric. vet.
Chem., 4 (2), 44-48.
An assessment of the value of dilute
dust insecticides for the protection of
stored maize in Kenya.
J. appl. Ecol., 3(1), 169 - 179.
Inspection methods for detecting insects
in stored produce. Trop. stored
Prod. Inf., (12), 481 - 494.
ASHMAN, F., ELIAS,
D.G., ELLISON, J.F. and SPRATLEY, R.
An instrument for detecting
insects within food grains. Milling,
32, 34 & 36.
ATTIA, R. and KAMEL,
The fauna of stored products in
U.A.R. Bull. Soc. ent. Egypte, 49, 221
Airtight storage of grain, its effects on
insect pests. II.
Aust. J. agric. Res., 7 (1), 7 - 19.
Airtight storage of grain, its effects on
insect pests. III. Calandra oryzae
Aust. J. agric. Res., 8 (6), 595 - 603.
The effects of percussion on insect pests
of grain. J. econ. Ent., 55 (3),
301 - 305.
Airtight storage of grain - its effect on
insect pests. IV. [\IRhyzopertha
dominica (F.) and some other
Coleoptera that infest stored grain.
J. stored Prod. Res., 1 (1),
25 - 33.
Pesticide residues as hazards.
PANS, 15 (1), 2 - 8.
The infestibility of stored paddy by
Sitophilus sasakii (Tak.) and
Rhyzopertha dominica (F.).
Bull. ent. Res., 51 (3), 599 - 630.
Studies on the oviposition of Rhyzopertha
dominica (F.) in rice and paddy.
Bull. ent. Res., 53 (4), 621 -
The chilled storage of grain.
Ceres, (5), 15-20.
CABRAL, A.L. and
Da occorrencia de algunas pragas
de produtos ultramarinos en poroes de
navios mercantes (Carreira
da Guine). (Occurrence and distribution
some pests of stored
products in ships' holds of cargo ships of the Guinea
Garcia de Orta, 8 (1), 47-57.
The infestation of cowpeas in the Western
Region of Nigeria. Trop. Sci., 3
(4), 154 - 158.
CASWELL, G.H. and
Effect of moisture content on
germination and growth of fumigated maize
Emp. J. exp. Agric., 28, 139 - 149.
and KAUFMANN, H.H.
Deterioration of stored grains
by fungi. A. Rev. Phytopath., 3, 69 -
and LOPEZ, L.C.
Pathology of stored seeds.
Proc. int. Seed Test. Ass., 28, 701 - 711.
Fungi in stored products.
Trop. stored Prod. Inf., (15), 3 - 14.
'Insack' treatment of maize with
insecticide for protection against storage
pests in Uganda.
E. Afr. agric. J., 24 (4), 244 - 250.
Hermetic sealing of a stack of maize
with bituminous roofing felt.
Trop. Agric., Trin., 37 (1), 53
I : a review of yam storage practices and of information on
J. stored Prod. Res., 2 (3), 229 - 244.
Sacks for the storage of food
grains. Trop. stored Prod inf.,(17),
Insect infestation of stored raw cocoa in
Ghana. Bull. ent. Res., 51 (1),
203 - 222.
DAVEY, P.M. and
humidity equilibria of tropical stored produce.
Part 3. Legumes, spices and beverages.
Trop. stored Prod. Inf., (13), 15 - 34.
Aluminium phosphide for bulk grain
fumigation in Uganda. E. Afr. agric.
J., 24 (2), 103 - 105.
A note on the control of bean pests in
Uganda. E. Afr. agric. J., 24 (3),
174 - 178.
Coleoptera associated with stored
products in Uganda. E. Afr. agric. J.,
(3), 199 - 201.
Storage of maize in a prefabricated
aluminium silo in tropical conditions.
E. Afr. Agric. J., 25 (4), 225 -
Experiments on the crib storage of maize
in Uganda. E. Afr. agric. J., 26
(1), 71 - 75.
CHAVES, A.M. and EDJE, O.T.
Drying or anaerobically
preserving small lots of grain for seed or food.
Agron. J., 61 (6), 913 -
CSIRO develops aeration system for
farm-stored grain. Pwr Fmg Bett. Fmg
Dig., 78 (10), 10 - 13.
Low-cost farm buildings for storage and
equipment housing in Ghana.
Ghana J. agric. Sci., 1 (2), 165
The storage of cereals by farmers in
Northern Nigeria. Trop. Agric., Trin.,
41 (3), 197 - 212.
Control of insects infesting stored
sorghum in Northern Nigeria. J. stored
Prod. Res., 1 (2), 145 - 158.
Maize storage: the problem of
today. Trop. stored Prod. Inf., (14), 9
Observations in Kenya on the flight
activity of stored products insects,
particularly Sitophilus zeamais
Motsch. J. stored Prod. Res., 4 (2),
317 - 329.
GOLUMBIC, C. and
Radiation disinfestation of
grain and seeds. Proc. Symp. Food
Karlsruhe, 1966, pp 473 -
488. Vienna : Int. Atomic Energy
GONEN, M. and
Changes in the microfloral composition of moist sorghum stored
Trop. Sci., 10 (2), 107 - 114.
Warehouse ecology studies of bagged
maize in Kenya. I. The distribution
of adult Ephestia (Cadra)
cautella (Walker) (Lepidoptera, Phycitidae).
II. Ecological observations
of an infestation by E. cautella. III. Distribution
of the immature stages of E.
cautella. IV. Reinfestation following
fumigation with methyl bromide gas.
J. stored Prod. Res., 6 (2): I, 147 - 155;
II, 157 - 167; III, 169 -
175; IV, 177 - 180.
The protection of dried sea-fish in
South Arabia from infestation by
Dermestes frischii Kug.
(Coleoptera, Dermestidae). J.
stored Prod. Res.,
2 (4), 331 - 350.
Prevention of waste of agricultural
produce during handling, storage and
Trop. stored Prod. Inf., (15), 15 - 23.
Food storage in the developing
countries. J.R. Soc. Arts, 117 (5156),
562 - 579.
Build-up of free fatty acid in Northern
Nigerian groundnuts. Trop. Sci., 9
(4), 211 - 237.
Infestation control in stored groundnuts in
Northern Nigeria. Wld Crops,
15 (2), 63 - 67.
Entomological problems of food storage
in Northern Nigeria. Bull. ent.
Res., 43 (1), 111 - 144.
A summary of estimates of optimal and
minimal conditions for population
increase of some stored products
insects. J. stored Prod. Res., 1 (2),
177 - 184.
Losses caused by insects and mites in
stored foods and feeding stuffs. Nutr.
Abstr. Rev., 35, 285 - 293.
HOWE, R.W. and
Some laboratory observations on
the rates of development, mortality and
oviposition of several
Bruchidae breeding in stored pulses.
Bull. ent. Res.,
55 (3), 437 - 477.
Hazards of storing high-moisture grain
in airtight silos in tropical countries.
Trop. stored Prod. Inf., (18), 9
Moisture migration in horizontally
stored bulk maize: influence of graininfesting
insects under South African
conditions. S. Afr. J. agric. Sci., 1
(2), 175 - 193.
The effect of physical disturbance or
'turning' of stored maize on the
development of insect
infestation. I. Grain elevator
studies. S. Afr. J.
agric. Sci., 6, 55 - 64.
KAPUR, N.S. and
Storage and preservation of
fatty foods. Food Sci., Mysore, 8, 257
On open-air and underground storage in
the Sudan. Bull. Soc. ent. Egypte,
53 (44), 129 - 142.
The relative susceptibility of some
varieties of sorghum to Trogoderma
Emp. J. exp. Agric., 30 (118), 133 - 136.
Protection of cob maize stored in
cribs. E. Afr. agric. J., 19 (2), 69 -
Control of insects attacking maize on
the cob in crib stores. E. Afr. agric.
J., 23 (4), 275 - 279.
LEPELLEY, R.H. and
Experiments in the use of
insecticides for the protection of grains in storage.
Bull. ent. Res., 45 (2), 295
An annotated record of Coleoptera,
Lepidoptera, Hemiptera and Hymenoptera
associated with stored produce
in Jamaica. Trop. Agric., Trin., 40
The productivity and rate of development of
Sitophilus oryzae (L.) (Coleoptera,
Curculionidae) in various parts
of Kenya. J. stored Prod. Res., 4 (1),
31 - 51.
Stored products insect control in
Kenya. Trop. stored Prod. Inf., (18), 13
Treatment of large grain stores in Kenya
with dichlorvos slow-release strips
for the control of Cadra
cautella. J. econ. Ent., 63 (1), 288 -
Theory of moisture in stored produce.
Trop. stored Prod. Inf.,
13)., 9 - 14.
MAJUMDER, S.K. and
Toxicity of calcium phosphate to
some pests of stored grain. Nature,
Lond., 202 (4939), 1359 -
KRISHNAMURTHY, K. and GODAVARI BAI, S.
Pre-harvest prophylaxis for
infestation control in stored food grains.
Nature, Lond., 192 (4800),
375 - 376.
NARASIMHAN, K.S. and SUBRAHMANYAN, V.
Insecticidal effects of
activated charcoal and clays. Nature,
(4693), 1165 - 1166.
MAJUMDER, S.K. and
Some aspects of the problem of
bulk storage of foodgrains in India.
Wld Rev. Pest Control, 2 (2),
25 - 35.
SHARMA, S.M. and SINGH, S.P.
Fungi associated with
[\i]Sorghum vulgare under different storage conditions
PANS, 15 (3), 365 - 367.
PAGE, A.B.P. and
Fumigation of insects.
A. Rev. Ent., 8, 239 - 264.
The protection of stored seeds from
insects and rodents. Proc. Int. Seed
Test. Ass., 28 (4), 893 - 909.
The onset of insecticide resistance among
field populations of stored product
J. stored Prod. Res., 1 (1) 3 - 8.
KADKOL, S.B., RAO, M.N., SWAMINATHAN, M. and SUBRAHMANYAN, V.
Effect of insect infestation on
stored grain: II. Studies on husked, handpounded,
milled raw rice and
parboiled milled rice. J. Sci. Fd
Agric., 8 (9),
512 - 516.
PINGALE, S.V., RAO,
M.N. and SWAMINATHAN, M.
Effect of insect infestation on
stored wheat. I. Studies on soft wheat.
J. Sci. Fd Agric., 5 (1), 51
Moisture content - its significance and
measurement in stored products.
J. stored Prod. Res., 3 (1), 35
A possible rapid method of determining
the moisture content of high-moisture
J. Sci. Fd Agric., 21 (9), 465 - 467.
Contribution a la conservation du niebe ,
du vouandzou, du mais, des
arachides et du sorgho.
(Contribution to the preservation of cowpeas,
(Bambarra groundnut), maize, groundnuts and
Agron. trop., Nogent, 23 (9), 982 - 986.
Essai et enquete sur greniers a mais
togolais. (A trial and survey on
Togolese maize granaries).
Agron. trop., Nogent, 24 (8), 709 - 718.
MOOKHERJEE, P.B. and SHARMA, G.C.
Pusa bin for grain storage
Indian Fmg, 15 (1), 14 - 16.
A study of rice storage under tropical
conditions. J. agric. Engng Res., 4
(3), 243 - 254.
The distribution of insects in stacks of
bagged groundnuts in Northern
Bull. ent. Res., 54 (4), 689 - 713.
WILBUR, D.A. and MILLS, R.B.
Irradiation of early instars of
the Angoumois Grain Moth. J. econ.
63 (4), 1241 - 1247.
The control of insects infesting groundnuts
after harvest in the Gambia:
The practical application of control measures.
Trop. Sci., 2 (3), 134 - 139.
Trials with small capacity grain silos in
Dar es Salaam, Tanzania. E. Afr.
agric. for J., 34 (2), 263 -
The metabolism of contact insecticides in
stored grains. Residue Rev., 17,
105 - 177.
SARID, J.N. and
Storage structures for large
scale handling and preservation of food grain.
Bull. Grain Tech., 3 (2), 62
SARID, J.N. and
Protection of marketable
grain. Bull. Grain Tech., 6 (1), 16 -
SARID, J.N., RAI,
L., KRISHNAMURTHY, K. and PINGALE, S.V.
Studies on the large scale
storage of food grains in India. Part
on the relative suitability
of cement concrete and aluminium bins for
Bull. Grain Tech., 3 (4), 135 - 141.
SARID, J.N., RAI, L.
and PINGALE, S.V.
Studies on the large scale
storage of food grains in India. Part
on the insect and
temperature fluctuations in bag storage of wheat.
Grain Tech., 5 (1), 3 - 11.
E.L. Effectiveness of green
electroluminescent lamps for attracting stored-product
J. econ. Ent., 63 (3), 726 - 731.
Plastics films for the bulk storage of
food. Plast. Inst. Trans. & J., 33
(103), 11 - 15.
STRONG, R.G. and
Germination of cereal, sorghum
and small legume seeds after fumigation
phosphide. J. econ. Ent., 53 (1), 1 - 4.
STRONG, R.G. and
Effect of methyl bromide and
hydrocyanic acid fumigation on the germination
of corn seed.
J. econ. Ent., 54 (8), 764 - 770.
Trials on the underground storage of maize
of high moisture content in
Bull. ent. Res., 48 (2), 397 - 406.
VENKAT RAO, S.,
NUGGEHALLI, R.N., PINGALE, S.V., SWAMINATHAN, M. and
Effect of insect infestation on
stored field bean (Dolichos lablab) and
black gram (Phaseolus
mungo). Fd Sci., Mysore, 9, 79 - 82.
VENKAT RAO, S.,
NUGGEHALLI, R.N., SWAMINATHAN, M., PINGALE, S.V. and
Effect of insect infestation on
stored grain: III. Studies on Kaffir corn
J. Sci. Fd Agric., 9 (12), 837 - 839.
Effects of grain moisture content on
residual toxicity and repellency of
J. econ. Ent., 52 (1), 131 - 134.
Physical methods of insect control.
Proc. Ent. Soc. Manitoba, 21,
18 - 27.
An appraisal of gamma irradiation for
insect control in cereal foods.
Manitoba Ent., 2, 37-45.
WILKIN, D.R. and
Polythene sacks for the control
of insects in grain. J. stored Prod.
6 (1), 97 - 101.
New storage, transportation and handling
techniques for tropical agricultural
Prot. Cult. Trop., Marseilles, 1965, pp 93 - 98.
Chambre de Commerce et
WRIGHT, F.N. and
The potential uses of plastics
for storage with particular reference to rural
Trop. Sci., 4 (2), 74 - 81.
Simple methods are given
converting English and
Following these is
a series of useful
for units of area, volume,
pressure and power.
The chart in Figure 3 is useful
for quick conversion
from meters and
centimeters to feet
and inches, or
For more accurate results
and for distances
greater than 3 meters,
use either the
tables in Figure 2 or
1 foot = 30.48cm
The chart in Figure 3 has metric
divisions = 0.3048m
of one centimeter to
three meters, 1 yard =
and English units in
inches and feet
to ten feet.
It is accurate to about
1 mile = 1.607km
plus or minus one
= 5280 feet
1cm = 0.3937 inches
= 39.37 inches
An example will explain how to use
= 0.62137 miles
Suppose you wish to find
= 1000 meters
how many inches are
equal to 66cm. On
"Centimeters into Inches" table look
down the leftmost
column to 60cm and then
right to the column
headed 6cm. This
gives the result,
centimeters FIGURE 2
(1 in. =
(1 cm. = 0.3937
The chart in Figure 5 converts pounds
and ounces to
kilograms and grams or
For weights greater than
ten pounds, or more
use the tables
(Figure 4) or conversion
See "Length Conversion,"
Figure 2, for an example
of the use of
On the chart, notice that there are
for each pound to
ounces. There are 100 divisions
only in the first
represents ten grams.
The chart is
accurate to about plus
or minus twenty
1 ounce = 28.35 grams
1 pound = 0.4536 kilograms
1 gram = 0.03527 ounce
1 gram = 2.205 pounds
(1 kg. = 2.20463
(1 lb. =
The chart in Figure 1 is useful for
from degrees Celsius
degrees Fahrenheit and
Although the chart is fast
and handy, you must
use the equations
below if your answer
must be accurate
to within one
Degrees Celsius =
5/9 x (Degrees
Degrees Fahrenheit =
1.8 x (Degrees
This example may help to clarify the
use of the
equations; 72F equals how
72F = 5/9 (Degrees F -32)
72F = 5/9 (72 -32)
72F = 5/9 (40)
72F = 22.2C
Notice that the chart reads 22C, an
error of about 0.2C.
Units of Area
1 Square Mile
= 640 Acres
= 2.5899 Square Kilometers
Kilometer = 1,000,000 Square
Meters = 0.3861 Square Mile
= 43,560 Square Feet
1 Square Foot
144 Square Inches =
0.0929 Square Meter
1 Square Inch
6.452 Square Centimeters
1 Square Meter
10.764 Square Feet
0.155 Square Inch
Units of Volume
1.0 Cubic Foot
= 1728 Cubic Inches
= 7.48 U.S. Gallons
1.0 British Imperial
Gallon = 1.2 U.S. Gallons
1.0 Cubic Meter
= 35.314 Cubic Feet
= 264.2 U.S. Gallons
= 1000 Cubic Centimeters
= 0.2642 U.S. Gallons
Units of Weight
1.0 Metric Ton
= 1000 Kilograms
= 2204.6 Pounds
= 1000 Grams
= 2.2046 Pounds
1.0 Short Ton
= 2000 Pounds
Units of Pressure
1.0 Pound per square
inch = 144 Pounds per square
1.0 Pound per square
inch = 27.7 Inches of Water*
1.0 Pound per square
inch = 2.31 Feet of Water*
1.0 Pound per square
inch = 2.042 Inches of
= 14.7 Pounds per
square inch (PSI)
= 33.95 Feet of Water
1.0 Foot of Water =
0.433 PSI = 62.355 Pounds per
1.0 Kilogram per square
centimeter = 14.223 Pounds per square
1.0 Pound per square
inch = 0.0703 Kilogram per
(*) at 62 degrees
Fahrenheit (16.6 degrees Celsius)
Units of Power
(English) = 746 Watts = 0.746
(English) = 550 Foot Pounds
(English) = 33,000 Foot
Pounds per minute
1.0 Kilowatt (KW) =
= 1.34 Horsepower (HP) English
(English) = 1.0139 Metric
Horsepower = 75 Meters X
Horsepower = 0.736
Kilowatt = 736 Watts