Soil Water Content As Affected By Crop Growth Stages, Different Management Practices and Soil Depth Under Dryland Conditions.

Soil water content is the most important factor controlling germination, root growth and emergence. The experimental design was factorial experiment laid out in RCBD with three replicates. The experiment consisted of five cropping systems, which were monocropping cowpea, monocropping maize, rotational maize, rotational cowpea and intercropping maize-cowpea. The three growth stages compared in this study were before tasseling/flowering, during tasseling/pod formation and during physiological maturity of maize and cowpea. The three locations of data collection were Potchefstroom, Taung and Rustenburg. Soil was sampled for the 0-0.15, 0.15-0.3, 0.3-0.6 and 0.6-0.9 m depth increments and soil water content determined using the gravimetric method. The growth stage before tasselling/flowering in maize/cowpea had significantly (P < 0.05) higher water content of 10.2, 10.8, 12.5 and 13.3% at the depth of 0-0.15, 0.15-0.3, 0.3-0.6 and 0.6-0.9 m respectively. Soil collected at Rustenburg and Potchefstroom had significantly (P < 0.05) higher water content of 13.5 and 10.2; 15.9 and 10.9; 18.3 and 12.8; 18.4 and 14.5% at the depths of 0-0.15, 0.15-0.3, 0.3-0.6 and 0.6-0.9 m respectively. Monocropping cowpea plots had significantly (P < 0.05) higher water content of 12.4% than other cropping systems at the soil depth of 0.3-0.6 m. The interaction effect of growth stage x location x season on soil water content at different soil depths contributed much to the significant of this study, with the implication that, soil water availability depends on stages of crop growth under different locations with different climatic conditions.