APPLYING THE CONCEPT OF AGRODIVERSITY TO INDIGENOUS SOIL AND WATER CONSERVATION PRACTICES IN EASTERN KENYA

Agrodiversity - the diversity of cropping systems, crop species and fa rm management practices has received increasing attention in recent ye ars as a way of spreading risk and supporting food security in resourc e-poor farming systems. This paper discusses the dynamic aspects of in digenous soil and water conservation (ISWC) practices in a semi-arid p art of Kenya. The objective is to show the range of sources of variabi lity and diversity that prevail in this environment, the responses of farmers to this variability, and the way farmers' rationalise the hete rogeneity of soil and water management practices. Methods used include d participatory surveys and evaluations, on-farm monitoring, soil and rainfall data analyses, and questionnaire surveys. Sources of variabil ity affecting cropping systems and land management practices included rainfall, soil fertility, farmer resource level and farm productivity. A decision-tree was developed to examine how biophysical and socio-ec onomic variability affected farmers' choice of ISWC. Different ISWC st ructures dominated on sandy and stony soils, respectively. Low resourc e farmers tended to choose cheaper and less labour demanding technique s, and constructed smaller ISWC structures than better endowed farmers . The largest diversity of ISWC practices was found on newly-opened la nd with mixed soils. Moreover, on-farm productivity levels indicated t hat costly investments in SWC are unfeasible, as this would further in crease the risk for negative returns to farming. The wider implication s of the results are that SWC interventions in marginal areas should b uild on the existing agrodiversity and an understanding of the complex interactions between environmental and socio-economic factors that gi ve rise to differences in farming systems and land management practice s. (C) 1998 Elsevier Science B.V. All rights reserved.