Simulation of yield and evapotranpiration of forage maize using AquaCrop model

Crop models such as AquaCrop can be a useful tool for better management of water consumption. However, these models should be evaluated before applying. In this study, the accuracy of the AquaCrop model in estimating shoot fresh weight and evapotranspiration of Maize in different soil fertilities and soil textures was evaluated. Field experiments were done as a factorial experiment in a completely randomized design with three soil texture treatments (including silty clay loam, loam and sandy loam) and three levels of soil fertility (including without added fertilizer, adding one and two percent of the fertilizer into the soil). The study was conducted in summer of 2012 in Jey and Qahab region in Isfahan. Results of this study showed that prediction of the model for shoot fresh weight of fodder maize was extremely efficient. The normalized root mean square errors (nRMSE) of the shoot fresh weight of fodder maize for calibration and validation stages were obtained as 0.87% and 0.67%, respectively. Predicting maize evapotranspiration during the growing season by the model had a higher error rate. Maximum and minimum of the root mean square error was obtained in the sandy loam soil with the addition of two percent of the fertilizer treatments (SLF2) and loam soil by adding one percentage of the fertilizer (LF1) with values of 0.88 and 1.42 mm per day, respectively. Results of this study showed that the mean values of RMSE and nRMSE in simulating maize evapotranspiration for sandy loam soil were 1.16 mm and 24.3% that were more than mean values of RMSE and nRMSE for silty clay loam soil type and loam which were 1.08 mm, 26.2% and 0.93 mm, 20.4%, respectively. However, the model accuracy in predicting maize evapotranspiration was varied at different levels of soil fertility depending on soil types so that the maximum value of RMSE in the loam soil was obtained in treatment without fertilizer (LF0) and in sandy loam soils in treatment with two percent fertilizer (SLF2).