Effects of residue mulch and tillage on soil moisture conservation

The effects of selected soil management practices (conventional tillage, tied ridges and crop residue mulching) on soil moisture conservation in a semi-arid area of Kenya were studied during the short rains period, 1988, and long rains period, 1989. Three treatments, mulching, tied ridges and conventional tillage with three replications of each practice under a completely randomized block design, were used in the study. Nine experimental plots, each 4 m × 10 m were set up on a slope of 2%. During the study period, soil moisture was monitored on a weekly basis using the neutron probe at predetermined depths to a maximum depth of 120 cm. Calibration of the neutron probe was done for the soil at two depth ranges: 0–90 cm and 90–120 cm. The need to calibrate the probe for the 90–120 cm depth arose due to the presence of iron concretions within this depth range. The results obtained from this study showed that overall, crop residue mulching did result in more moisture down the profile throughout the two seasons within 2 years than the other two tillage practices. The tied ridged plots had the lowest amount of soil moisture in the soil profile during the two seasons. Thus the application of surface crop residue mulch seems to be the best soil management practice for increased soil moisture conservation and improved crop performance in rainfall marginal areas of Kenya.