Sorghum Production Using Zai Pits and Integrated Soil Fertilty Management in Kitui County, Kenya
Kerubo, Getare Ednah
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Food insecurity in the arid and semi-arid land regions of Kenya is partly caused by climate change and variability resulting to prolonged dry periods and water scarcity directly affecting crop production. The dry lands of Kitui County have been facing soil fertility decline over the years as well as low crop yields due to crop failure resulting to food insecurity and low economic returns. This is associated with the poor soil and water conservation methods practiced in the area. The objectives of the study were: i) to determine the effect of zai pits in combination with selected integrated soil fertility management (ISFM) technologies on the chemical properties of soils in Kabati, Kitui County, ii) to determine the effect of zai pits combined with selected integrated soil fertility management(ISFM) technologies on sorghum yield in Kabati, Kitui County and iii) to assess the economic feasibility of using zai pits combined with selected integrated soil fertility management (ISFM) technologies on sorghum production in Kabati, Kitui County. An experiment was set up in a randomized complete block design (RCBD) with 8 treatments replicated thrice, sorghum gadam variety used as the test crop. The treatments were; zai+ manure, zai+60kg N ha-1, zai+manure+30kg N ha-1, zai+ no inputs, conventional + manure, conventional + 60kg N ha-1, conventional+manure+30kg N ha-1 and conventional + no inputs. Soil sampling was done at a depth of 0-15 cm before setting up the experiment and at the end of the experiment. The samples were analyzed in the laboratory for total nitrogen, available phosphorous, soil pH, soil organic carbon and electric conductivity using standard methods. Data on sorghum yield and economic returns was subjected to analysis of variance and mean separated using Standard Error of Difference at p<0.05. The results indicated that total nitrogen reduced significantly (p<0.05) in zai with sole manure and zai with manure and fertilizer treatments after the two cropping seasons. Organic carbon significantly (p<0.05) reduced in conventional without input, zai with fertilizer and zai with manure and fertilizer treatments. Soil electrical conductivity significantly (p<0.05) increased in zai with fertilizer, zai with manure and zai with manure and fertilizer treatments. Available phosphorous increased significantly (p<0.05) in conventional with sole manure, zai with fertilizer and zai with manure. Sorghum grain yields were significantly (p<.005) higher in zai with manure, zai with fertilizer and zai with manure and fertilizer compared to the conventional counterparts during the SR2018 season. In the same season stover yields were significantly (p<0.05) higher in zai with manure and mineral fertilizer compared to their conventional counterpart. During the SR2018 season, return to labour was significantly higher (p=0.0269, p=0.0252, p=0.0379, respectively) in zai with fertilizer, zai with manure and zai with manure and fertilizer compared to their conventional counterparts. The findings of this study highlight the importance of rain water harvesting using zai pits and the use of manure in combination with mineral fertilizer supplements in improving soil fertility, enhancing crop yields and profitability. To enhance crop yields, this study recommends that Zai pits should be used with a combined application of both organic resources and inorganic soil fertility inputs. The farmers should also be trained on the importance of using zai pit as a soil and water conservation technique in ASALs to improve crop production.