Sustainability and profitability of intensive cropping technologies on the dryland Vertisols of Sudan: A simulation approach with EPIC

There have been rapid increases in the mechanized farming of the Vertisols in the Gadaref region, the primary dryland sorghum production area in Sudan. The Gadaref region contributes approximately 50 percent of sorghum produced in the dryland mechanized farming system of Sudan. Sorghum yields in the Gadaref Vertisols have been declining over time. The purpose of this thesis is to evaluate the long term sustainability and profitability of the present and some alternative intensive technologies for sorghum production. Using the EPIC simulation model, the thesis evaluated: sorghum yield distributions with present practices including continuous mono-cropping of sorghum and alternative sorghum fallow systems; the potential of new intensive technologies (improved sorghum cultivars, fertilizers, and tied ridging) for increasing and sustaining yields of sorghum; the profitability over time of present and new technologies. The decline in sorghum yields in the continuous monocropping system and in the fallow systems, due to increasing soil fertility stress was indicated. Compared to present practices, the use of improved sorghum cultivars fertilized with nitrogen fertilization resulted in a sustainable increase in sorghum yields in the long run. The improved sorghum cultivars, with moderate nitrogen fertilizer and improved agronomy were highly profitable, having first degree dominance, over the predominant traditional activity of continuous sorghum cropping. Even with farmers agronomy there was second degree dominance of the improved cultivar and nitrogen practice over the traditional activities and other new technologies. Other new technologies were also evaluated but did not improve upon the above technology combination.