AN EVALUATION OF SUSTAINABLE CULTURAL-PRACTICES FOR RAIN-FED SORGHUM PRODUCTION ON VERTISOLS IN EAST SUDAN

Cultural practice trials have been conducted in east Sudan since 1986 to demonstrate that Vertisols can be managed successfully for sorghum production using only shallow tillage (0.08 m depth) or manual no-till planting. The trials have compared tillage inputs and crop yields (outputs) of traditional manual no-till planting methods with shallow overall weeding tillage, using tractor-drawn shallow discing (one-way or wide-level discs) at three levels of manual weeding (none, once and twice). Four systems of field preparation were compared: (1) manual operations with broadcast seeds; (2) manual operations with row planting using the Saluka planting stick; (3) broadcast seed using tractor-drawn one-way discs; (4) crops planted in rows using the one-way discs fitted with a seed box. The results for three consecutive growing seasons, with very different total rainfall and distribution, show that (1) early weed control after planting has a very significant influence on grain yield; (2) shallow discing provides effective weed control and reduces the need for subsequent manual weeding; (3) crop yield is related to rainfall distribution rather than the seasonal total. These results confirm and justify the need for long-term tillage trials to clarify the temporal effect climate has upon crop yield and the local economy in semi-arid regions.