Wheat yield modeling under water-saving irrigation and climatic scenarios in transition from surface to sprinkler irrigation systems

Abstract

• Remote sensing can provide historical growth data for crop modeling on large scales. • Water productivity could be improved by 18% by deficit irrigation. • Irrigation could be reduced by 150 mm in wet and normal years with no yield loss. • Irrigation strategy under erratic rainfall is vital in improving water productivity. • Sprinkler irrigation in dry years decreased water productivity. Water-saving through deficit irrigation management is a prominent approach to improving water productivity (WP) in sustainable agriculture. However, it is not feasible to assess many irrigation scenarios and their impact on WP. Therefore, crop modeling is a valuable tool for evaluating the effect of different irrigation scenarios on yield and WP. No study has evaluated surface irrigation and transition to sprinkler irrigation under different climatic scenarios and irrigation strategies. In this study, historical remotely sensed crop growth and field-measured grain yield (GY) data were used to calibrate and validate the AquaCrop model for a wide wheat-cultivated area. Then, the model was used to investigate the impact of different surface deficit irrigation strategies under five different climatic scenarios, including wet, normal, and dry on WP and GY. Then the model was used to assess the effect of different sprinkler irrigation strategies and their application efficiency on WP and GY under the climatic scenarios. Based on AquaCrop scenario analyses, irrigation water requirements varied between 270 and 620 mm in different growing seasons regarding rainfall characteristics (amount and distribution). Also, reducing irrigation water by 30% improved WP between 0% and 18% in different growing seasons. Moreover, sprinkler irrigation could improve WP and sustain yield production only in normal and wet years with high application efficiency and proper irrigation strategy. Otherwise, sprinkler irrigation would decrease WP and increase the pressure on water recourses. Therefore, in such areas with erratic rainfalls, synchronizing irrigation strategy with the rainfall characteristics increases WP and sustains crop production.