Since the beginning of the seventies, the Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ - German Technical Co-operation) has carried out bilateral and sector-based post-harvest projects with priority given to the African continent. These projects were financed by the Federal Ministry of Economic Co-operation and Development (BMZ).

In Togo, Benin and other African countries in the eighties, GTZ extended a stored cowpea protection method based on the use of neem oil (SPV/GTZ, 1988). This method offered the following advantages in small scale farming:

In practice, harvesting and oil extraction and application go through the stages described in Figure 1 (see the following page). Given the considerable losses caused by bruchids and the advantages mentioned, there is no doubt that the recommendations responded to a real and serious problem, and that the proposed technology had all that was required to attract the interest of the rural target groups.

The extent of damage (up to about 30% loss of dry matter after eight months in storage) seemed to justify the cost of applying imported chemical products in all the cases. Where the LGB was present, the use of binary powders containing two active ingredients was recommended. The application techniques extended by GTZ in Togo and Benin included:

With this range of treatments, chemical means were available for the control of insect pests in all the modern and traditional maize storage systems. The extension services which then were supported by the GTZ were responsible for providing the necessary assistance to ensure the correct use of insecticides in a way that will present no risks to the population and the environment. However, co-operation with extension services has not always been smooth.

In order to offer a solution to the technical problems of grain storage in cereal banks which were constructed in large numbers, especially in the Sahel zone, GTZ designed a standard warehouse (Harnisch & Krall, 1986) which seemed to combine all the advantages of an ideal village storage facility:

With the construction of such warehouses, the preservation of cereal was henceforth no longer considered a major concern by those in charge. To summarise, it can be noted that most cereal storage problems seemed to have found practical technical solutions towards the end of the eighties. Nevertheless, a strange trend was observed: the lot of farmers had not changed much in spite of the progress made.

In reality, the recommendations described above, as well as most others, like the protection of traditional granaries with rodent guards, were in most cases not well accepted by the target groups for various reasons. Below are some of the major arguments raised against the above innovations.

Furthermore, the bitter taste of neem oil discourages many farmers from applying it on beans meant for consumption, even though the taste is completely removed when soaked for a long time in water.

In the research carried out in Togo and Benin, many farmers complained about the ineffectiveness of powder products for the protection of stocks. This is a frequent complaint which may be due to the following reasons:

If furthermore one considers the problems of chemical products distribution in the regions concerned, it is hardly surprising that the use of synthetic products for stock protection is still the exception among most African farmers.

The technical performance of fumigatable warehouses has never been in doubt. However, very few of these storage units have been constructed, and hardly any is being run profitably. The reasons for this situation must be sought in the socio-economic and administrative problems faced by all grain banks (Günther & Mück, 1995). Briefly, if a grain bank is badly designed and managed (which was mostly the case), the question of whether loss of grains can be prevented or not does not arise.

Generally, all technical innovations in the post-harvest sector posed socio-cultural or socio-economic problems, for example:

The divergence between technical recommendations and the realities of rural life translates in most cases into a low adoption rate and unsustainable innovations. To really improve the standards of living of the target groups, additional factors had to be taken into account, especially socio-economic considerations. It also appeared that the state is not in a position to resolve all the problems associated with the development of post-harvest systems. This is why non-governmental organisations, private organisations such as traders were addressed more and more in interventions.

It was at this point that GTZ embarked on participatory development of new technologies. In the first place, this involves the analysis of the problems, based on all the tools provided by the "Participatory Rural Appraisal" technique. Incidentally, the solutions are developed, optimised and established with the participation of interested parties. The novelty of this approach which is more evident in Benin (Kossou et al., 1996), lies in the fact that the local officers live in the village with the farmers, and that they are closely involved in the daily decisions taken by the rural families. This approach is a first in the post-harvest sector in Africa.

In the first place, FAO and GTZ developed a methodology for the analysis of post-harvest systems based mainly on the approach used by La Gra (1990). To date, two case studies have been carried out in order to obtain an overall picture of the problems of specific post-harvest systems, and to test and improve the practice of the method. The first study was carried out by GTZ in Kenya, the second by FAO in Zambia.

The GTZ study, which was carried out in collaboration with the University of Hanover, was on Irish potato and sweet potato (Anonymous, 1997). Below are the main results:

The study carried out in Kenya showed the importance of some key elements in the method used in the post-harvest systems analysis:

The post-harvest system analysis is a very valuable strategy tool. It provides an integrated overview of the different levels, which are usually examined separately, such as the macro-economic and legal framework, the behaviour of the system, bottlenecks in the chain, as well as the potential for investments and development.

As seen in the previous chapter, the results of the first post-harvest system analysis carried out in Kenya surpassed the expectations of experts. In order to fine-tune the method it is absolutely necessary to introduce performance indicators. Generally, the production, stability and flexibility of a system serve as performance indicators. Here, it involves the ability to respond to future production and demand trends. These indicators should be prepared especially for the following two areas:

In the second place, the constraints identified can be classified according to their degree of priority and evaluated according to their influence on the other correlation within the system.

With regard to post-harvest systems development, it is the government's responsibility to define the policy framework for development and to establish public services which the private sector does not provide. Such "public goods" include the creation of infrastructures, the assurance of a legal guarantee, fair market activities, etc. Governments should not try to intervene actively in the market, but rather intervene indirectly by encouraging the private sector through support services like extension.

Fig.2.

Deviations in the performance of the system from a "social optimum".

The working group can act as an organising committee for intervention in the post-harvest sector. This approach requires a certain flexibility on the part of public institutions. The assistance of GTZ in post-harvest systems development can include the following activities:

Fig.3.

Co-ordination between different levels of stakeholders in post-harvest system development.

In this programmes approach, GTZ functions as an intermediary. Other financial donors should be actively involved. Financial co-operation can be associated more closely with technical co-operation. Project activities are to a large extent planned by the members of the working group.