Soil moisture variability effects on maize crop performance along a toposequence of a terraced vertisol in Machakos, Kenya

Recurrent droughts are often associated with crop failure and therefore food insecurity especially in semi-arid areas of Kenya. A study was conducted in Machakos County in the long rain and short rain seasons of 2014 to determine the effect of soil moisture variability on crop performances and yields along the toposequence of a terraced vertisol. The crops were grown as either sole maize, sole beans or maize-bean intercrop. An experiment was laid in a randomized complete block design (RCBD) and each treatment replicated three times. Data collected included maize height and leaf area index at 9th leaf and tassel stage, maize and bean yield and soil moisture content. The results showed significant variations (p<0.05) in soil moisture content, maize height, above ground maize biomass yield and maize and bean grain yield at different slope positions. The lower slope position recorded significantly (p<0.05) higher mean soil moisture content (20.6%) compared to the middle (16.1%) and upper (16.3%) slope positions. The lower slope position recorded significantly (p<0.05) higher mean biomass yield of 4.94 ton/ha compared to the middle and upper (4.30 and 4.12 ton/ha, respectively). Results of this study indicate that terracing has an effect on soil moisture content variability and that farmers can benefit from low-cost technology using soil and water conservation structures to increase yields. Key words: Soil moisture variability, terrace embankment, slope position, toposequence, vertisols, crop yields.