Utilization of crop simulation model "APSIM" in investigating climate change effects on sorghum yield in Gedarif area

Abstract

Climate change has significant impacts on food security pertaining to its negative effects on grains production especially under traditional and vulnerable rainfed agricultural systems in Sudan. Hence, the Objective of this study was to study climate change impacts on rainfed sorghum production through different scenarios using APSIM model and studying the length of growth season trends during the last twenty years 1991-2010. To achieve this objective a field experiments were conducted for two successive seasons 2009 and 2010 in Gedarif area. The experiment treatments comprised of three methods of sowing; wide level disc, in rows 80 cm apart using row planter and at bottom of ridges 80 cm as an in-situ water harvesting technique. Two sorghum varieties were used Arfa- Gadamak 8 and Wad Ahmed in the first season, Arfa Gadamak 8 and Bashaer in the second season. Nitrogen fertilizer of zero and 0.5N in the form of Urea was applied. The length of the growth season was studied using daily climate data for 20 years to calculate the ET0 for 10 days interval. The actual climate and biophysical data in addition to data generated from experiments were used for APSIM to simulate sorghum yields for different scenarios for the period from 1979 to 2010. The results showed that the length of the growth season has no consistent trends, but the average season length during the studied period was shorter than the average of preceded period 1961-1990. More water stresses of varying magnitude were observed during the last 10 years of the studied period. APSIM outputs showed yield reductions in all the scenarios. The study revealed that more tuning of APSIM model is required through extensive iv soil-water-crop data under rainfed conditions using sophisticated monitoring equipment. The study, also, supported the use of in-situ water harvesting technology under low rainfall conditions. Still, more research needed on sowing date update according to the changing growth season length due to the climate change with a support of intensive network of automatic weather stations in Gedarif area.