Improved water productivity in intensified agroforestry systems: supplementary irrigation from farm ponds in semi-arid Olepolos highlands in Kajiado district: a research paper

The project was aimed at determining the be st combination of crops and trees for an intensified Agroforestry system that would ma ximize land productivity in a sustainable way. Thereafter a criteria and procedure for desi gning the size of pond that would fulfill the irrigation requirements for the same Agroforest ry system (optimizing the pond size) was to be determined. The project used supplementary irrigation and irrigation water productiv ity as the bases of arguments. An Agroforestry system was modele d for the area which included cereal legume vegetable and fodder crops and trees. The total water requirement for the system was computed to be 1400m 3 of which 40m 3 was to be obtained from supplemental irrigation Rainfall and catchment characteristics were an alyzed for the study area. The total available catchment area for the pond system (both within the farm and outside) was considered as approximately 0.5 acres. The design rainfall was based on the monthly ra infall data recoded for a 10-year period from Kajiado Maasai Rural Trading Centre meteorol ogical station. It was determined to be 640 mm. Seepage was assumed to be negligible assuming the system had lined ponds. The volume lost to evaporation was computed to be 47.5m 3 from data got from Narok meteorological station which experiences similar weather with Kajiado. The losses expected from the drip irrigation system were taken as 9.72 m 3 Pond capacity to support the Agroforestry system was computed to be 100m 3 . The total rainwater harvest potential was computed 1160m 3 /yr. The potential rainfall was capable of providing a continuous supply of water for the system. Water productivity for each Agroforestry element was then computed on th e basis of FAO documen ted expected yields. A procedure for determination of water productivity benchmark was then established. A two- week irrigation schedule was drawn up using wa ter balance for the Agroforestry system. A procedure for designing of pond capacity us ing water productivity benchmark was then established. Shapes of ponds were also propos ed and dimensioning procedures outlined

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