Abstract
Water harvesting technologies and soil conservation measures promote water-nutrient synergy and increase agricultural production in the dryland zones of sub-Saharan Africa. To alleviate water stress, soil fertility decline and reduce runoff, soil and water conservation measures are promising options whose impact on agricultural productivity has not been fully explored. The objective of the study was to assess the effect of using zai pits in combination with selected soil fertility ammendments. An experiment was conducted in Tharaka Nithi County, Kenya to assess effects of using Zai pits in combination with selected amendments on sorghum production. The experiment was set up in a Randomized Complete Block Design (RCBD) involving 12 soil and water conservation treatments with three replications per block. Experimental data were subjected to analysis of variance and mean separation done using least significant difference (LSD) at p < 0.05. Zai pit in combination with tithonia amendment had the highest yields of 4.30 Mg ha(-1) during short rains season of 2013 while Zai pit in combination with cattle manure had the highest yield of 4.18 Mg ha(-1) during short rains season of 2014. Conventional planting with full rate NPK had the highest benefit-cost ratio (BCR) of 3.58 while Zai pit without input had the least BCR of 0.99. The experiment showed that Zai pit technology contributed to increments of yields in comparison to conventional planting although its BCR was lower than conventional planting with similar amendments. However, both Zai pit and conventional practices should be used in combination with organic and inorganic amendments to enhance yields in sorghum production.