Neco Model Questions Vol1 2023 Geography Question 39

A farmer intends to grow maize on 5 ha. The expected yield without any constraints is 4.5 t ha\(^{-1}\). The soil fertility index of the field is 0.8 (optimum = 1.0) and each 0.1 unit below optimum reduces yield by 12 %. The seasonal rainfall is 850 mm (optimum = 1000 mm) and each 10 mm deficit reduces yield by 0.5 %. Fertiliser (N) is applied at 120 kg ha\(^{-1}\) (optimum = 150 kg ha\(^{-1}\)); each 10 kg deficit reduces yield by 1 %. Pest damage is expected to destroy 8 % of the produced yield. (a) Compute the net expected yield (in tonnes) under these conditions. (b) If the farmer raises fertiliser application to the optimum level and adopts pest control that cuts damage to 3 %, what is the new net yield and the percentage increase over the original net yield?