Evaluation of the AquaCrop model for barley production under deficit irrigation and rainfed condition in Iran

The AquaCrop simulation model which has been developed by Food and Agricultural Organization (FAO) has the ability to assess the crop production under different irrigation water management. In this research, 2-year data of rainfed barley (2005-2007) from a research project at upstream of Karkheh river basin (Lorestan Province) were used to evaluate the accuracy of the AquaCrop model. The experimental treatments included: rainfed, one irrigation event at sowing time and one irrigation event at spring, that were performed in farmers' fields. The AquaCrop model was evaluated to predict the effect of deficit irrigation and rainfed conditions on yield, soil water content and percentage of green canopy cover. The mean normalized mean root square error for comparison between the measured and predicted values for canopy cover percentage, soil water content, and grain yield were 8.7, 12.4 and 9.2%, respectively, that showed good model accuracy. Efficiency of the model in yield estimation, soil water content and green canopy cover percentage were 0.91, 0.8 and 0.98, respectively. Agreement index for yield was close to 1.0 that showed compatibility of these predicted values with actual values. The results showed that the AquaCrop model is appropriate tool to simulate barley yield under rainfed and deficit irrigation conditions in the study area. This model is a suitable tool to determine sowing date in rainfed conditions based on first effective rain.