Evaluating AquaCrop Model for Winter Wheat under Various Irrigation Conditions in Turkey

Farming winter wheat in Central Anatolia of Turkey traditionally is rainfed. Crop yields are frequently affected in this region because of the drought events of varying severity. There is apparent necessary for an aim appraisal of the effect of dryness on this critical crop, to answer the contradiction whether irrigation is essential or not. For this reason the FAO-AquaCrop (Ver.5.0) crop water productivity model was preferred to predict attainable yields of winter wheat (Triticum durum L.) under four different irrigation regimes. Field experiment was conducted under four different irrigation treatments in Central Anatolia Region of Turkey during 2008-2010. The AquaCrop was calibrated with 2008-2009 field data and model validation was performed using 2009-2010 data. Model simulation results showed that model simulates soil water content in root zone (SWC), canopy cover (CC), grain yield (GY) and aboveground biomass (BM) of wheat reasonably well. The average root mean square error (RMSE) between simulated and observed SWC, CC, GY and BM were 21.1 mm, 7.1%, 0.32 t ha(-1) and 0.34 t ha(-1). Nash-Sutcliffe efficiency (EF) and index of Willmott (d) also were obtained 0.89 and 0.98 for CC, 0.74 and 0.93 for SWC, 0.98 and 0.92 for BM, 0.95 and 0.82 for GY. Model predicted canopy cover, grain yields and biomass with high accuracy while soil water content at 90 cm soil depth was estimated in the moderate accuracy. The results presented that AquaCrop model can be suggested as a convenient model for decision-making whether irrigating wheat is in the priority or not at the limited water resources areas.