Evaluation of SWAP Model for Simulation of Early and Mid Corn in Different Plant Densities under Sprinkler Irrigation

Corn is one of the most important agricultural crops in Iran. In order to achieve appropriate yield, biomass and water use efficiency, it is necessary to evaluate the effect of irrigation amounts, cultivar types and plant densities on corn yield. Because of time-consuming and high cost in field studies, crop models have been proposed to study mentioned scenarios. In order to evaluate SWAP, a field study was conducted on two maize cultivars (V1 and V2 representing median cultivar SC500 and early cultivar Sc302, respectively) under different plant densities (D1, D2 and D3 representing 75000, 85000 and 95000 plants.ha-1, respectively, for SC500 and 80000, 90000 and 100,000 plants.ha-1 for SC302 cultivar) with different irrigation volumes (I1, I2 and I3 indicate as 75, 100 and 125% irrigation demand, respectively) in Karaj during two years (2006-2007). Results showed that SWAP had the best accuracy to simulate corn yield in V1, I3 and D3 in comparison to other treatments. SWAP accuracy was better in V2, I3 and D2 treatments for simulation of corn biomass. The model precision for water productivity was better in both cultivars, I3 and D3. In general, based on normalized root mean square error, the model accuracy for simulation of corn yield, biomass and water productivity were 0.14, 0.13 and 0.16, respectivly. SWAP efficiencies for mentioned parameters, with values equal to 0.98, were acceptable. So, it is proposed to use SWAP for simulation of yield, biomass and water use efficiency under above mentioned treatments.