Nitrogen and phosphorus balances of Kindo Koisha farms in southern Ethiopia

This paper describes soil N and P balances calculated at field and farm lev el in Kindo Koisha, southern Ethiopia. The balances were calculated for eig ht farms representing two agro-ecological zones (highland and lowland) and four socio-economic farmer groups (rich, medium, poor and very poor). Proce sses quantified included mineral fertilizer, organic matter, deposition, N fixation (inputs) and harvested products, removed residues, leaching, denit rification and water erosion (outputs). Measurements of N and P flows were made in the four major farm components: enset-garden, darkoa, tare root and shoka fields. Field scale analysis showed that N and P balances were eithe r in equilibrium or positive in most of the farm components across all farm s, suggesting that soil fertility is being maintained or even increasing. H owever, the shoka field, one of the most important components in terms of c ontribution to total farm output, had strongly negative N balances in all f arms. P balances were mostly positive although slight deficits were occasio nally observed. The aggregated farm scale balances varied considerably acro ss socio-economic groups and agro-ecological zones. N depletion was severe for rich farmers in the highland and for poor farmers in the lowland. Diffe rences in N and P balances were also observed between agro-ecological zones . There is a need for a more targeted approach to soil fertility interventi on that differentiates between farm component, agroecological zone and soci o-economic group. (C) 1998 Elsevier Science B.V. All rights reserved.