Performance and field practice of smallholder irrigation: The case study of Mitunguu irrigation scheme of Kenya

Abstract

The main objective of this study was to investigate performance and field irrigation practice of a smallholder scheme in Kenya. Farmers' irrigation practices were assessed through observations and questionnaires. Performance was evaluated using sprinkler discharge coefficient, Christiansen's uniformity (Cu), and distribution uniformity (DU). Soil samples were analyzed for texture, bulk density and moisture retention. Results indicated excessive leakages in the water conveyance system. In the low-pressure zone (LPZ), discharge coefficient was low, about 0.74, compared to 0.96 in the high-pressure zone (HPZ). Cu was about 81 % in the LPZ, and about 75% in the HPZ, indicating excessive water losses in the HPZ that can cause environmental degradation. DU was about 71% in the LPZ, but low (about 65%) in the HPZ. Bulk density was about 1.1 g/cm3, indicating compaction, possibly caused by over-irrigation. Farmers did not have a well-defined irrigation scheduling method. Available soil water storage was about 92 mm for shallow-rooted crops, which can be used to schedule irrigations. Performance can be improved through appropriate water management methods such as maintenance of the water conveyance system, use of at least one scientific irrigation scheduling method, educate farmers on crop water requirements, among others.