IMPACT OF CLIMATE CHANGE ON SORGHUM PRODUCTION UNDER DIFFERENT NUTRIENT AND CROP RESIDUE MANAGEMENT IN SEMI-ARID REGION OF GHANA: A MODELING PERSPECTIVE

This study evaluates the potential impact of climate change on sorghum (Sorghum bicolor (L.) Moench) grain yield under different crop residue and nutrient management systems in a smallholder farming system. The Agricultural Production Systems Simulator (APSIM) was used in this scenario analysis. Two crop residue management types (crop residue retention in soil and crop residue removal) and fertiliser management (no fertilisation and application of 40, 30 kg P ha^-1) were the scenarios analysed using climate change (CCD) and historical (HD) weather data to simulate sorghum yield. Comparing grain yield under the two weather conditions, there was a 20% reduction in grain yield as a result of climate change when no fertiliser was applied compared with a yield increase of 4% with the application of 40 kg N, 30 kg P ha^-1. The impact of crop residue management on grain yield was lower under climate change weather conditions than under historical weather conditions. This can be attributed to higher soil moisture stress which also contributed to lower rate of soil carbon decomposition in the top soil. Instability (inter-annual standard deviation) in grain yield was higher under climate change (0.13 to 0.21) weather conditions than under historical (0.04 to 0.11) weather conditions. This was reflected in higher change in yield, thus, making sorghum production under rain-fed agriculture more risky, particularly to the smallholder (low input) farmers.