The Effects of Tillage and Residue Mulching on Soil Moisture Conservation in Laikipia, Kenya

The effects of selected soil management practices (conventional tillage, tied ridging and crop residue mulching) on soil moisture conservation in a semi-arid area of Kenya (Kalalu, Laikipia) were studied during the short rains period, 1988, and long rains period,1989. Two test crops maize and beans were used to monitor the effects of conserved moisture on crop performance (emergence,height and ground cover) and yield. Three treatments with three replications of each practice under a completely randomised block design were used in the study.Nine experimental plots,each of size 4m by 10m 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 upto a maximum depth of 120cm. Crop performance was also monitored on a weekly basis throughout the crop growing periods.Calibration of the neutron probe was done for the soil (ferric Acrisol) at two depth ranges: 0-90cm and 90-120cm. The need to calibrate the probe for the 90-120cm 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 despite lagging behind in seedling emergence, did conserve more moisture throughout the two crop growing periods and had a better crop XVl performance and yield than the other two practices. The vigorous crop growth and good ground cover under residue mulch was attributed to a high soil moisture content in the soil profile. The tied ridged plots had the lowest amount of soil moisture and hence the poorest crop performance and yield. Thus the application of surface crop residue mulch seems to be the best soil management practice for .incr ee sed soil moisture conservation and improved crop perfomance and yield in Kalalu, Laikipia.