The Effect of Time of Seedbed Preparation on Conserved Soil Moisture and Grain Yield of Wheat at Njoro, Kenya

Abstract

The effect of tillage implements and time of seedbed preparation on soil moisture status and grain yield of wheat at Njoro was determined over a period of four years. There were no significant differences in yield, soil moisture status and efficiency of operation among tillage implements tested. But there were significant differences in grain yield of wheat, soil moisture status due to the effect of time of seedbed preparation. Early seedbed preparation prevented regrowth of weeds and volunteer crop plants. This resulted in increased stored moisture and an increase in yields. Besides this early time of seedbed preparation appeared to –be related to some residual factors other than soil moisture which influenced yield but were not determined. The degree of yield reduction due to initial time of seedbed preparation depended on the amount of rainfall during crop life. The two were inversely related. From the results of study, early seedbed preparation was expected to be always beneficial at Njoro and probably all other areas with growing conditions similar or more adverse than Njoro. This includes all those areas which receive about 300 mm of rainfall before planting and significantly less than 1,000 mm of rainfall during crop life. In such areas stubble land must be cultivated within two months after harvesting for the next crop in order to avoid adverse moisture loss and yield reduction. These findings are of special importance to crop production in marginal rainfall areas.