Effects of Tillage Practices and Organic Cropping Systems on the Yield of Sorghum (sorghum bicolor L.) and Sweet Potato (Ipomoea batatas L) in Yatta Sub-County, Kenya

Abstract: The study was conducted between October 2012 to February 2013 short rain season (SRS) and April 2013 to August 2013 long rain season (LRS) in semi-arid Yatta sub-county, to evaluate the influence of tillage practices, cropping systems and organic inputs on the yield of sorghum and sweet potato. A Randomized Complete Block Design with a split-split plot arrangement replicated thrice was used. The main plots were tillage practices (TP); Oxen plough (OP), tied ridges (TR) and furrows and ridges (FR). The Split-plots were cropping systems (CS); mono-cropping (MC), intercropping (IC), and crop rotation (CR) while split-split plots were organic inputs; Farm Yard manure (FYM), Minjingu Rock Phosphate (MRP), combined MRP and FYM (MRP+FYM) and the control. Test crops were sorghum and sweet potatoes with Dolichos (Dolichos lablab) and chickpea (Cicer arietinum L) either as intercrops or in rotation. Plant sampling was done by harvesting the grain and tuber and yield determined by weighing with a precision balance. The yields increased significantly (P≤0.05) with application of MRP+FYM of 16.37 and 1.38 t ha-1 for sweet potatoes and sorghum mono-crop, respectively under TR were observed. There was also significant (P≤0.05) yield increase of chickpea and dolichos under combined TR, IC of sorghum with chickpea (1.44 t ha-1) and dolichos (1.38 t ha-1) and with application of MRP+FYM during SRS of 2012. Improved yield of srghum and sweet potatoes were attained with the combined TR, MC and with application of MRP + FYM.