MODELING THE IMPACT OF CLIMATE ON THE POTENTIAL YIELD OF MAIZE IN THE UPPER WEST REGION USING THE AQUACROP MODEL

The potential yield of maize cultivated under rain - fed was simula ted using the FAO AquaCrop model using climate data from the Wa Meteorological Station as a case study for the region. The potential maize yield was simulated by delineating the climate and the soil as a water storage reservoir to store the rainfall as the only limiting factors to the potential yield of maize. Hence the only limiting factors to the potential yield of maize were temperature stress and water stress which are climate driven. It’s assumed that other factors such as access to certified viable hi gh yielding seeds, soil fertility and productivity, pests and diseases control, weeds control and other economic and technological constraints are non - limiting and favourable for potential yield of maize. The results indicate that climate has a great impac t on maize yield hence when to plant and which variety to plant is critical. The simulation was run on three most common maize varieties planted in the region (Obatanpa, Aburohima and Dodzi) cultivated on deep uniformly sandy loam soil. Th e simulated avera ge potential yield of Obatanpa for the 2009, 2010 and 2011 farming seasons planted between late - May to mid - July which is the recommended planting period were; 12.61 ton/ha, 12.36 ton/ha and 12.48 ton/ha respectively. That of Aburohima fo r the same farming seasons planted between early - June to late - July were; 9.58 ton/ha, 8.97ton/ha and 9.62 ton/ha respectively. And that of Dodzi planted for the same seasons between early - June to early - August were; 8.82 ton/ha, 8.12 ton/ha and 8.63 ton/ha respectively.