Chapter Five Structure of the Compost Heap and Major Methods of Preparing Manure

A. Structure of compost manure

The construction of a compost heap is similar to that of any other structure. A complete heap comprises layers of various materials and each layer has special functions in the heap. Basically, a complete heap of compost manure consists of the following parts:

1. Layer '0': grass/dry leaves

This layer has several functions.

(a) It helps in aeration of the heap.

(b) It prevents too much water from soaking the refuse as excess water easily trickles downwards.

(c) It absorbs exhausted nutrients from the upper layers of the decomposing heap. This layer should be 10 to 15 centimetres thick.

2. Layer 1: Refuse

This is the layer that is being made to decompose and it absorbs plant nutrients from the overlying layers, preserving them instead of letting them get exhausted in the soil. Usually, the width of this layer is 15 centimetres.

3. Layer 2: Dung

This layer consists of dung or any other type of livestock fertilizer. The function of this layer is to produce nitrogen in the heap so as to enable the micro-organisms function well in the decomposing of the refuse. This layer also adds phosphate and other plant nutrients to the heap. It also fixes bacteria and fungus in the heap. This layer should be 2 centimetres wide. If the farmer does not have livestock dung, he may use other sources of nitrogen, such as legumes, left-overs or artificial fertilizer such as sulphates of ammonia.

4. Layer 3: Ashes

Ashes contain calcium and potassium, which are required by the plant and help in the decomposition process by regulating the pH in the heap. This layer is two centimetres wide.

5. Layer 4: Soil

This layer has the following roles:

(a) Prevents the ammonia produced in the lower layers from escaping into the atmosphere.

(b) Prevents loss of temperature and humidity from the heap.

(c) Increases plant nutrients in the heap.

This layer is two centimetres wide.

NOTE: Water is sprinkled on top of the soil layer. This is intended to increase the moisture in the lower layers, and especially the refuse layer, so that the microorganisms can function well in decomposing it.

6. Inner cover

This is the cover on the heap. As explained earlier, the cover has three roles:

(i) It helps preserve temperature and humidity in the heap.
(ii) Regulates air circulation therein.
(iii) Helps condense the water vapour in the heap, thus maintaining its moisture level.

The role of this cover is to prevent too much rain water which may cause:

· exhaustion of plant nutrients in the heap.

· loss of humidity in the heap.

· saturation of the heap and

· blocking of air spaces in the heap.

Farmers intending to start the production of compost manure are usually confronted by two main barriers:

(a) Inadequate water.

(b) Lack of dung or other farmland manure since they do not keep livestock.

In an effort to deal with the above impediments, an explanation of how to make compost manure under these conditions is offered below.

There are several ways in which compost manure may be made. Any particular method to be adopted by the farmer will depend on several factors:

(a) The capability and ingenuity of the farmer in making compost manure.

(b) Climatic conditions.

(c) The amount of refuse he possesses.

(d) The type of rubbish available.

(i) On the earth's surface.
(ii) In compost pits.
(iii) In special boxes.

This method is used by farmers residing in regions that have adequate rains or where there are other sources of water. This availability of water removes one of the impediments in the making of compost manure. When using this method, it is important to achieve a heap that is 1.5 metres high, 3 metres wide and 3 metres long.

(a) Compost preparation in areas with adequate water and livestock dung

Requirements

(i) Grass/dry leaves.

(ii) Adequate refuse especially food remains, banana skins, cassava, yams, Irish potatoes, sweet potatoes, coffee, weeds, rice husks, millet, maize, bulrush millet, wheat, etc.

(iii) Dung and/or other types of manure from livestock.

(iv) Adequate water.

(v) Ashes.

(vi) Soil.

(vii) Inner cover, for example old sacks and mats.

(viii) Outer cover.

(ix) The following implements: matchet, sickle, fork and an irrigation can.

Preparation

(i) Avail yourself of dry grass and leaves.

(ii) Prepare and mix refuse as explained in Chapter Four, Sections 1 (c) and (d).

(iii) Demarcate the area for making compost manure. This area should be 3 metres long and 3 metres wide. However, these measurements can be slightly altered depending on the amount of refuse available. It is important to remember that smaller heaps do not produce quality manure since they do not decompose well. The same applies to larger heaps since the mixing of the component parts is more difficult without special machines. Therefore, if the farmer has a lot of refuse to decompose, it is advisable for him to have several heaps of average sizes instead of one large one.

Fig. 6: Various implements used in me preparation of compost manure

Caution

(i) Where possible, the site for manure preparation should be near the livestock shed in order to get the dung easily.

(ii) The site for manure preparation should be near a farm.

(iii) For hygienic reasons, the manure should not be prepared near an occupied house.

(iv) It is also advisable that the above requirements be met before the construction of the heap starts because the structure must be started and completed within a day.

(v) If possible, the site should be under a shade so as to prevent the fertilizer from drying due to direct sunshine. If no natural shade is available, you will need to prepare some shelter.

Step 1

Prepare three sites, the first one for the construction of the heap and the second and third ones for the shuffling of the component parts.

Label them Site 1, Site 2 and Site 3 (see Figure 7 below). Loosen the soil at Site 1, which is the place for building the heap. There are three main advantages of doing this.

(a) Excess water is removed from the heap.

(b) The worms found in the soil get to the heap.

(c) Aeration of the heap is regulated.

Fig. 7: Construction and shuffling sites of the heap

Step 2

Erect pegs at each comer of these sites. The height of the pegs should be 1.8 metres. The pegs help in guiding the farmer during the preparation and shuffling of the heaps so that he knows their demarcations. If the site is likely to be flabby, the foundation of the heap should be made of leaves or sticks as they help in regulating air circulation. However, if there is no such likelihood, then there is no reason for using the leaves or sticks.

Step 3

Start layer '0' with dry grass or leaves. It should be 10 to 15 centimetres thick.

Fig. 8: Site for the construction and shuffling of the compost heap

Step 4

The first layer will consist of the refuse prepared and shuffled as explained in Chapter Four. It should be 15 centimetres thick.

Step 5

The second layer will consist of dung. It should be 2 centimetres thick.

Step 6

The third layer will consist of ashes. It should be 2 centimetres thick.

Step 7

The fourth layer will consist of soil. It should be 2 centimetres thick.

Step 8

Sprinkle water on the above layers. The amount should be only enough to percolate to all layers; however, too much water will affect the proper decomposition of the heap.

Fig. 9: A farmer sprinkling water on a heap

Step 9

Repeat steps 4 to 8 (see Fig. 11 below). This repetition should be undertaken until the heap attains a height of 1.5 metres; higher than that will make the heap too heavy, resulting in three main problems.

(i) There will be too much heat which the micro-organisms will not withstand.

(ii) Air circulation will be impeded.

(iii) The shuffling of the heap will be difficult, especially in the absence of special equipment.

During the shuffling, erect a peg in the middle of the heap ensuring that it sinks in adequately.

fig. 10: Erect a peg in the middle of the heap

Step 10

Remove the pegs from the stalk. At times one peg could be left intact to serve as a gauge of the temperature and the heap. The resultant hole(s) aid in the circulation of air in the heap.

Step 11

Cover the heap with the inner cover.

Step 12

Place or construct a roof (outer cover), a raised platform or shed above the heap and wait for maturation of the manure to take place before applying it to the farm.

Fig. 11: A complete heap of compost manure

Note

The farmer is advised to sprinkle water on the heap regularly. If there is rain, it is important to remove the inner and outer covers occasionally for the heaps to receive a moderate amount of rain. Care should be taken to avoid soaking the heap with water all the time.

Step 13

Shuffle the heap (see Chapter Four). The first shuffling should be done on Site 2 fourteen (14) days following the completion of the heap structure. The second shuffling should be done 14 days thereafter and should be done on Site 3. The 14-day period may be extended depending on the rate of decomposition. During the shuffling, ensure that the layers that were at the top, the sides and the base of the heap are put in the middle to enable them decompose properly.

Fig. 12: A farmer thoroughly mixing and shuffling the heap

Shuffling has the following advantages:

(a) It enables every part of the heap to get enough air and moisture.

(b) Every part gets the micro-organisms required (as the shuffling distributes these micro-organisms throughout the heap). In this way, the decomposition process is accelerated.

(c) It enables uniform distribution of warmth in the heap, resulting in uniform decomposition of the heap.

(d) It reduces chances of the formation of layers that might otherwise be air- and water-tight to the point of blocking free penetration into the heap.

If the above steps are carefully followed, the compost manure should be ready for use after 10 to 12 weeks since the completion of the heap structure. Incase the decomposition was satisfactory, the process of constructing the heap has to start again. The farmer will then correct all the mistakes that may have been made in the first instance. Competent farmers ensure that they always have one or more extra stalks under decomposition. The number applies also to the heaps undergoing maturation or those already mature and are awaiting application on the farm.

(b) Compost preparation in areas without livestock but with availability of water

Requirements

(i) Dry grass or leaves.

(ii) Enough refuse; for example food remnants, banana skins, cassava, Irish potatoes, sweet potatoes, yams, sugar-cane peelings, weeds, etc.

(iii) Domestic ashes.

(iv) Enough water.

(v) Dry grass that can easily decompose.

(vi) An inner cover.

(vii) An outer cover.

(i) There should be enough dry leaves or grass.

(ii) Prepare and shuffle the refuse as explained in Chapter Four.

(iii) Prepare three sites whose measurements are as explained above; one on which to construct the heap and the rest for the purpose of shuffling. They should be labelled Sites 1, 2 and 3 as shown in Figure 8.

Step 1

Loosen the soil on Site 1.

Step 2

Erect pegs at the comers of Site 1. The pegs should be 1.8 metres high. Erect two or three other pegs at different places of Site 1. As already explained, if the site is likely to be flabby, start the construction with tree branches. If the site cannot be flabby, then there is no need to do so.

Step 3

At Site 1, place layer '0' that is composed of grass or leaves. The thickness should be 10 to 15 centimetres.

Step 4

Prepare the first layer. This layer consists of the refuse to be decomposed. The thickness should be 30 centimetres.

fig. 13: Heap of compost manure showing me various layers

Step 5

The second layer consists of domestic ashes (or lime) and it should be 2 centimetres thick.

Step 6

The third layer consists of soil and is 2 centimetres thick.

Step 7

Sprinkle adequate water on the fourth layer so that all layers are adequately moist.

Step 8

Repeat steps 4 to 7 until the stack reaches a height of 1.5 metres.

Step 9

Remove the pegs that are in the middle of the heap.

Step 10

Place the inner cover over the heap.

Step 11

Place the outer cover over the heap.

Step 12

If decomposition progresses well, after a few days the height of the heap reduces by 15 to 30 centimetres and the shuffling should be done on Site 2 after 30 days. During this process, ensure that the refuse on top, at the sides and the base of the heap is put in the middle. This facilitates uniform decomposition.

Start preparing another stack at Site 1, which is now empty. After another 30 days, transfer the decomposing refuse from Site 2 to Site 3 and that one on Site 1 to Site 2. By the third month, the compost manure will be ready. The compost manure (which is now humus) should be removed from Site 3 and be either applied to the farm or stored for future use. The refuse in Site 2 may be shuffled onto Site 3 and that on Site 1 onto Site 2. A new stack may be prepared on Site 1, which is now empty. Following this process, after the first four months, the farmer may have fresh compost manure on a monthly basis.

(c) Compost preparation without use of water in areas with plenty of fresh coffee foliage and cattle

Requirements

(i) Plenty of easily decomposing plants.

(ii) Ashes.

(iii) Leguminous plants and products.

(iv) Plant remains; for example, fruit peelings, barks of coffee trees, etc.

(v) Soil preparation: the farmer should ensure that there is an adequate supply of plants that hold a lot of water. One preparation method is that of growing these plants. The farmer should also have enough legumes.

Prepare three sites 1, 2, and 3 for the construction and shuffling of the compost heap. Each site should be 3 metres in length as well as in width.

However, these measurements may be reduced depending on the amount of available refuse and manure, as well as other needs. The steps to be followed are as follows:

Step 1

Cut the plants into 10-centimetre bits and split them where necessary. The split bits should be left for one week in the cattle sheds so that they may mix up with dung and urine. The same applies to legumes. The mixture should be removed from the cattle shed after one week.

Step 2

The construction of the heap should start on Site 1 by placing a layer of grass or leaves. This layer should be labelled '0' and should be 10 to 15 centimetres thick.

Step 3

Arrange the mixture explained in step 1. This first layer should be 40 centimetres thick.

Step 4

Arrange the second layer which consists of barks of fruits, coffee berries, etc. The width of this layer depends on the amount of bark available.

Step 5

Arrange the third layer which consists of ash. It should be 2 centimetres thick.

Step 6

Arrange the fourth layer which consists of soil. Its should be 2 centimetres thick.

Step 7

Press the layers down sufficiently by trampling upon them.

Step 8

Repeat steps 3 to 7 until the stack is 1.5 metres high.

Step 9

Place the inner cover on top of the heap.

Step 10

Construct the outer cover.

Step 11

Use Site 2 to shuffle the heap after 14 days. After 21 more days, relocate the refuse heap on Site 2 onto Site 3.

Fig. 14: Structure of the compost heap

As explained earlier, this process is continued on rotational basis. After 21 more days (which is the maturation stage) the compost manure will be ready for application on the farm.

D. Preparation of compost manure in pits

The second main method of making compost manure is through the use of compost pits. However, this is applicable only where there is lack of water or rain. Generally, the three ways of making compost manure which were explained earlier are used where there is plenty of water or rain; they are also applicable in the making of compost manure in pits. This means that the explanation offered above in respect to making compost manure is applicable to preparing it in pits. Therefore, repetition is not necessary here, except to emphasise that the site for making the pit should have the following requirements:

(a) It should be flat.

(b) The water table should be low - there should be no possibility of availability of underground water.

(c) There should be no possibility of water getting into the pits.

(d) To limit the problem of inadequate air the pit should not exceed a depth of one metre.

(e) The edges of the pit should have a slope so as to facilitate good service to the pit, especially that one of shuffling the contents. The pits are numbered 1, 2, and 3 similar to the sites explained earlier. After filling the pits, cover them with the inner and outer covers.

E. Preparation of compost manure in boxes

The third major method of making compost manure is through the use of boxes. This is done by farmers who need small quantities of manure or those with small quantities of refuse but who have the ability to buy or make the boxes.

Fig. 15: Three boxes used for the preparation of compost manure

The boxes are open on both ends, the top and the bottom. Each box measures one square metre and may be made from bricks, timber, iron sheets, etc. as long as they are able to preserve heat, facilitate circulation of air and retain adequate moisture. Three boxes are required for a good shuffling of the manure.

Requirements

(a) Adequate rubbish.
(b) Three boxes open both at the top and bottom.
(c) Livestock manure, especially cowdung.
(d) Domestic ash.
(e) Enough water.

Preparation

(a) Prepare and shuffle the rubbish to be decomposed as explained in Chapter Four.
(b) Prepare the boxes.
(c) Prepare livestock manure, domestic ashes and enough water.

Steps to Follow

Step 1

Loosen the soil at the site where the compost manure will be prepared.

Step 2

If necessary, put in place a mechanism for letting in air from the bottom as explained earlier. Leaves, timber, layers of bricks, etc. may be used.

Step 3

Place or build the box on top as stated under Step 2.

Step 4

Build a heap inside the box as follows:

Layer '0'- Dry grass/leaves - 3 centimetres
Layer 1- Refuse -15 centimetres
Layer 2 - Dung - 2 centimetres
Layer 3 - Ashes - 2 centimetres
Layer 4 - Soil - 2 centimetres

Sprinkle water on these layers.

Step 6

Apart from layer '0', repeat layers 1 to 4 until the box is full.

Step 7

Place the inner cover on top of the box.

Step 8

Build a roof (outer cover) on top of the box to prevent an improper decomposition of the refuse or spoilage.

Step 9

After 14 days, the heap in box 2 should be shuffled. The second shuffling is to be done after 14 days when the refuse in box 2 is moved into box 3. If another shuffling is necessary, it will be done in another 14 days. Following this, the refuse should be left alone to undergo decomposition and for the fertilizer to mature.

Usually, compost manure is ready for use within 12 weeks following the preparation of the heap in the box.

Note

In cases where the farmer is unable to prepare compost manure due to unavailability of some essential items, the farmer should ensure that all the refuse coming from plants and animals should be made to decompose and returned to the soil. This means that the remains of crop plants after harvest or preparation, food left-overs, rubbish swept from the house, or other refuse, should not be discarded aimlessly.

It is very helpful when farmers see for themselves the good quality of plants brought about by the application of compost manure on the farm. We wish to encourage all farmers to be more modem by preparing and using compost manure, thus contributing to soil conservation and the protection of the environment.