14. agroforestry research in kenya: an overview

14.3  ICRAF's research station at Machakos

In 1980 the Kenya Government gave ICRAF a 40-hectare site to be developed into a field station. Initially the field station was mainly developed for demonstrations of agroforestry technologies for extension personnel, policy makers and researchers. But gradually the station has turned into a research station with modest laboratory facilities. This field station in Machakos is the only such research facility that ICRAF manages on its own.

The demonstrations that were established during the 1980s were of three main types:

• Demonstrations of multipurpose tree species. Seven species were planted in macroplots (Leucaena leucocephala, Acacia albida, Gliricidia sepium, Balanites aegyptiaca, Prosopis juliflora, Sesbania grandiflora, Acacia nummelaria), and another 80 species planted in microplots.

• Demonstrations of agroforestry technologies, e.g. woodlots with Grevillea robusta and Gliricidia sepium, boundary planting, live fences, soil-conservation technologies (barrier hedgerows, bench terraces with trees on the edges of terraces, fanya juu with trees below the risers, trees with grasses on contours), alley cropping, windbreaks, and fodder banks.

• Demonstrations of experimental design (systematic designs, tree/crop interface, etc.)

Numerous visitors have benefited from these demonstrations, and the experience gained at the field station laid the foundation for the research which was developed within the AFRENAs.

From 1990 greater emphasis has been put on research. The collaborative research that began in the mid-1980s created a need for more scientific backing for strategic research issues and research methods. Most of the resources are now geared to research, aimed at answering the "how", "what" and "why" questions. Examples of research activities are:

•  Demonstration plots have been converted to research plots where different soil-conservation measures are assessed with regard to run off, erosion, etc.

•  Different species are investigated in component-oriented research with regard to spatial arrangement, cover versus barrier effects, agroforestry systems versus non-agroforestry systems, impact on long-term soil fertility, etc.

•  Efforts to quantify the tree-crop interface with regard to factors such as water, light, and shelter

• Comparisons of annual and perennial legumes for soil-fertility improvement

• Studies of tree root systems and root competition

• Comparisons between use of prunings from hedgerows for fodder and for soil-fertility maintenance

• Water balance and the hydrology of agroforestry systems

• Provenance trials of Gliricidia sepium and Cajanus cajan while at the same time testing experimental design.