| Agro-forestry in the African Humid Tropics (1982) |
|Traditional agro-forestry systems: Prospects for development|
Summary of discussion: Traditional agro-forestry systems
In the discussions on traditional agro-forestry systems and their prospects for development, the first major point which emerged was that insufficient attention had been paid to the improvement of traditional cropping systems, in short, to make them economically viable as well as to meet subsistence needs. To continue to divorce agriculture from forestry was to be moving in the wrong direction, and this was especially true in the humid tropics. One participant observed that the value of mixed cropping systems was being demonstrated all around us, but that we have been blinded by the success of monocultures in the temperate zone. A "farming systems" approach was strongly advocated, although it was recognized that such an approach was relatively rare and demanded large inputs of scarce, trained personnel to be effective.
It was pointed out that the rapidly increasing population density was leading to smaller farms, yet these had to meet the basic food needs as well as provide cash income. Stable systems must be developed, and research must be carried out to determine whether agro-forestry will indeed provide greater benefits to the small farmer. The claim that higher diversity will increase stability (i.e., lessen risk) was questioned, as the data were still ambiguous. Certainly from a management viewpoint a higher diversity of crops makes it difficult to maximize the yield of the individual components. The problem of crop compatibility was also raised, and it was noted that there was great variability in the demands of annual crops for light, nutrients, water, etc. Similarly, crops vary greatly in their response to different management practices such as weeding. This means that each component within a given system will have to be tested independently and in situ in order to fully evaluate the potential of the system in question. Because of this inherent complexity we must use existing systems as guideposts, and only test systems which could fit in the existing socioeconomic milieu.
The question of tree root architecture was brought up, and the trade-off in the humid tropics between trapping nutrients with a dense, shallow root system vs. increased root competition was recognized. In this case further complications arise because the tree root system is also affected by the herbaceous component, and one would expect the balance to vary in accordance with rainfall, soil type, management practices, etc.
Several speakers felt that insufficient attention had been paid in the past to the development and management of the tree crop component. In this context the point was again made that one has to work within the context of the existing system by looking at the farmers' needs and then providing new plant material or other inputs which are demonstrably better. Improved coconut varieties and the Crop Diversification Project in Sri Lanka were cited as examples from outside Africa. It was also suggested that a type of planted fallow might be developed which would hasten the fertility recovery rate and provide a crop which could be harvested at the end of the fallow.