EVALUATING WHEAT PLANTING STRATEGIES USING A GROWTH-MODEL

The PUTU wheat crop growth model was used to determine optimal wheat planting strategies for Glen, South Africa (28-degrees-57'S, 26-degrees-20'E) using 50 years historical weather data. Aspects investigated were (1) the first date of prospective planting and (2) the fraction of the total available area allocated to each of four possible planting events. A total of 144 strategies were evaluated in terms of mean production, mean gross margin, production risk and stochastic efficiency. Highest mean production was simulated when the entire available area was planted on the first possible date after 5 May. Simulation results indicated that profit maximizing, risk averse producers should delay planting until 9 June and then plant the total available area as soon as favourable planting conditions occur. This strategy simulated a mean gross margin of R115 ha-1 and proved risk efficient. The potential of applying crop growth models and historical weather data to determine an optimal wheat planting schedule was demonstrated.