Effects of Selected Soil Water Conservation Strategies on Maize Yields and Soil Organic Matter Under Farmer Managed in the Central Highlands of Kenya.

Most farmers in Kenya have been experiencing a decrease in crop yields in the recent decades as a result of low water availability in the area caused by low and erratic rainfall, low inherent soil moisture storage capacity and poor water harvesting techniques. The main objective of the study was to evaluate the effects of the selected soil water conservation strategies (SWC) on soil organic matter, maize yields and yield stability under on-farm conditions. On-farm field experiments were installed at Mbeere South and Meru South Sub-Counties in Kenya to test three SWC strategies. The SWC strategies were evaluated for four cropping seasons. Maize and soil data were subjected to analysis of variance (ANOVA). Compared with the CT, results showed that in Mbeere South grain yields significantly increased under TR and MC during the LR12, the SR12 and the LR13 seasons. Tied ridging led to a 100% increase of the grain yields during the SR12 in Mbeere South. In Meru South, grain yields significantly increased under all the tested SWC strategies during the SR11, the LR12 season and the SR12 seasons. Mulching increased yields throughout the four cropping season in Meru South. Maize grain yields were more stable under TR and MC with residual variances of 0.107 Mg ha^-1 and 0.183 Mg ha^-1, respectively in Mbeere South compared to CT. Mulching, MT and TR strategies indicated yield stability with residual variances of 0.017 Mg ha^-1, 0.039 Mg ha^-2, and 0.155 Mg ha^-1, respectively, in Meru South. There was improvement in soil organic matter (SOM) under TR and MC Mbeere South and Meru South, respectively at the end of the experiment. The findings highlight the importance of SWC strategies for increased and stable maize yields of smallholder farmers under rain-fed farming system.