Abstract: Under the condition of limited available water resources, it is increasingly important to optimize irrigation strategies and adjust sowing dates to improve sustainability and profitable production. Authors calibrated and verified the crop parameters in AquaCrop model by using soil moisture, cotton growth, biomass and yield 2017−2018, and inputting the data into the meteorological, crop, irrigation, and field management modules. The biomass and yield of cotton under mulch drip irrigation in the oasis area of southern Xinjiang from 1988 to 2017 were simulated under 30 scenarios of different irrigation (TS1: 18mm, TS2: 24mm, TS3: 30mm, TS4: 36mm, TS5: 45mm, and TS6: 54mm) and sowing dates (D1: March 23, D2: April 3, D3: April 13, D4: April 23, and D5: May 3). The stability and sustainability of cotton production for 30 consecutive years were also analyzed. The results showed that the AquaCrop model could well simulate the cotton canopy coverage, aboveground biomass, and soil moisture under different irrigation and sowing dates. The normalized root mean square error (NRMSE) was less than 20%, and the synergistic index (d) and correlation coefficient (R2) were close to 1. The AquaCrop model underestimated cotton evapotranspiration (ET) and yield (Y) with relative error (RE) of −4.5% to 1.2% and −8.6% to −6.8%, respectively. However, it proves that AquaCrop model can be used for scenario simulation. The model prediction showed that the stability and sustainability of cotton production were less affected by sowing date, but increased with the increase of irrigation quota. With the same sowing date, the cotton biomass and yield increased with the irrigation quota. Under the 495mm irrigation quota, higher irrigation water efficiency was obtained, and the cotton yield was not significantly reduced. At the same time, under the 495mm irrigation quota, if the sowing date was postponed to April 13, it could save 36.78mm of water. If early maturing cotton seeds were used for sowing on April 23, it could save 65.34mm of water. Therefore, for regions with rich water resources, early sowing can be considered to obtain high yield, while for regions with poor water resources, late sowing is an economic and effective strategy to adapt to the current and future climate change and the shortage of water resources under the combination of varieties and cultivation models.

Key words: AquaCrop model, Irrigation quota, Planting date, Predicting yield