Tillage of clod-forming sandy soils in the semi-arid climate of Botswana
1981
Willcocks, T.J. (National Inst. of Agricultural Engineering, Silsoe, Bedford (UK). Overseas Div., Semi-Arid Dept.)
This paper outlines the findings of a four-season semi-arid tillage study in Botswana where the mean (30 year) rainfall is about 500 mm per annum but effective rainfall can be as low as 100 mm. The approach taken in this research was to give due consideration to the climate, the soil and the draught power as the three basic resources available for crop production. Pre- and post-tillage soil physical measurements (moisture, bulk density and strength) were conducted so that changes in soil conditions resulting from tillage, could be monitored. In-field measurements were made of the draught requirements of mould-board, chisel, sweep, disc and precision strip tillage implements so that energy values could be computed in relation to area cultivated and resultant crop yield. Precision strip tillage, a form of controlled traffic tillage, proved to be the most reliable and economic system for the cultivation of ferruginous sandy loam soils as this technique resulted in the microcatchment of scarce rain water.
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