Performance of the FAO AquaCrop model for wheat grain yield and soil moisture simulation in Western Canada

Wheat (Triticum aestivum L.) is the major grain crop grown in western Canada (Canadian Prairies) and soil water stress is considered the main limiting factor for crop growth. The objective of this study was to adapt and test the ability of the FAO developed AquaCrop model (v3.0) to simulate spring wheat yield and total soil water content (0–120 cm layer) on the Canadian Prairies. Crop yield and soil water content data collected from five experimental sites across the Canadian Prairies from 2003 through 2006 were used in the study. Results showed that the AquaCrop model can be used to model both wheat grain yield and soil water content on the Canadian Prairies with acceptable accuracy. Overall, the relationship between observed and modelled wheat grain yield for all sites combined produced a R2 of 0.66, slope of 0.96, index of agreement (d) of 0.99, root mean square error (RMSE) of 743 kg ha−1 and mean absolute error (MAE) of 611 kg ha−1. Similarly, the comparison between observed and modelled soil water content yielded a R2 of 0.90, slope of 0.73, d of 0.99, RMSE of 49 mm and MAE of 40 mm. The difference between observed and modelled grain yield was only 3%, while that between observed and modelled total soil water was 2%. Consequently, AquaCrop can be a valuable tool for simulating both wheat grain yield and soil water content on the Canadian Prairies, particularly considering the fact that the model requires a relatively small number of explicit and mostly intuitive input data which can be readily available or easily collected. However, the performance of the model has to be evaluated and fine-tuned under a wider range of conditions, which we hope will be the next step.