Using Combined AquaCrop Model and Thomas- Fering Method in Analyzing Rainfed Wheat Yield

One of the experts' suggestions for restoring Lake Urmia is to convert irrigated lands in to rainfed farming in the Urmia lake basin. Rainfed wheat farming might be considered as one of the effective alternatives to the irrigated areas. So, evaluating the soil available moisture as the most important limiting factor of the rainfed wheat farming is necessary. Since the field experiments are costly and time-consuming, application of the crop yield simulating models, e.g. AquaCrop which can estimate the crop yield based on soil water content with high accuracy, would be desirable. In this study, after calibration and validation of the mentioned model for simulating rainfed wheat yield in Tabriz plain during a period of 35-years (1360- 1395 HJ), the meteorological variables of the studied region were predicted for a 5-years ahead prediction interval using Thomas- Fering method. The rainfed wheat yield was then estimated using Aquacrop model for the period between 1396 and 1400 (HJ). Finally, management scenario for increasing the potential of rainfed wheat was proposed. The results of this study confirmed the ability of the conjunctive crop model and time series technique for simulating crop yield and meteorological variables in the studied region. Results showed that despite no significant change will be occurred in rainfall amount, ascending trend of the air-temperatures will cause an increase of about 13% in rainfed wheat yield during the next five years. Also, due to precipitation insufficiency for rainfed wheat farming, predicted supplemental irrigation is recommended equal to 40 mm, to increase the potential yield production.