Abstract

This study sought to address challenges faced by smallholder farmers in the drylands of Eastern Kenya including soil fertility decline and low profitability resulting from poor soil and water conservation measures. An experiment was set up at Kabati, Kitui County, Kenya in the year 2018/2019 seasons to evaluate the effects of the interaction of zai pits, cattle manure and fertilizer inputs on soil nutrients, sorghum yield and economic returns over two seasons. The field trials were set up in a randomized complete block design (RCBD). Eight treatments were replicated thrice with sorghum gadam variety as the test crop. The results indicated that total nitrogen significantly (p<0.05) reduced at the end of the two cropping seasons. Organic carbon significantly (p<0.05) reduced in conventional method 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 significantly (p<0.05) increased in conventional with manure, zai with fertilizer and zai with manure. Sorghum grain yields were significantly (p<05) higher in all zai treatments with fertility inputs compared to their conventional counterparts during the SR2018 season. During the SR2018 season, return to labour was significantly higher (p=0.0269, p=0.0252, p=0.0379, respectively) in zai treatments with fertility inputs compared to their conventional counterparts. The findings of this research study highlight the importance of using zai pits and the use of manure with mineral fertilizer supplements to improve soil fertility, enhancing crop yields and profitability.

Key words: Zai, soil fertility, soil chemical properties, integrated soil fertility management, cost-benefit analysis.