Yield and Rain Water Use Efficiency of Maize (Zea mays L.) Under Selected Soil and Water Conservation Technologies in the Central Highlands of Kenya

A study was carried out to assess the effectiveness of mulching, mbili intercrop, minimum tillage and tied ridging on soil and water conservation and improvement of maize yields under a rainfed farming system. The treatments, in three replicates, were laid out in a randomised complete block design on 2% slope runoff plots on a Nitisol in the sub humid region and a Cambisol in the semi-arid region of the central highlands of Kenya. Data on grain yield, soil properties, sediment, runoff and soil moisture were subjected to analysis of variance (ANOVA) using SAS 9.1.3. Results indicated highest maize grain yield of 4.9 Mg ha-1 under mbili intercrop followed by mulching (4.4 Mg ha-1 ). Minimum tillage resulted into the lowest (4.0 Mg ha-1 ) yield in the sub humid region. In the semi-arid region, weather variability characterised by meteorological dry spells occurred during the LR11 cropping season leading to total crop failure. During SR11/ 12, mulching and tied ridging were averagely the best with yields of 1.3 Mg ha-1 and 1.1Mg ha-1 . Mbili intercrop and conventional treatments had 0.1 Mg ha-1 and 0.7 Mg ha-1 , respectively. At the sub humid region, mulching, minimum tillage and mbili intercrop reduced sediment loss by 47%, 33% and 4% respectively compared to the control. In the semi-arid region,mulching, tied ridging and mbili intercrop reduced soil sediment loss by 65%, 48% and 39%, respectively compared to the control. Runoff was not significantly influenced by treatments in both experimental sites and was generally in the decreasing order of minimum tillage, control treatment, mbili intercrop and mulching in sub humid region; and control treatment, mbiliintercrop, mulching and tied ridging at semi-arid region. Soil nutrients improved remarkably with the conservation strategies.