Spatial and temporal distribution of water requirements and irrigation requirements of spring maize in Northeast China

Spring maize is one of the main grain crops grown in Northeast China. Drought and flood disasters frequently occur with irrational irrigation in this region; therefore, it is important to develop a rational irrigation system for spring maize production. In this study, the spatiotemporal distribution of water demand and shortage of spring maize in Northeast China was analyzed based on 70 years of experimental statistics from 26 stations in Northeast China, and crop water requirements were spatialized and analyzed using GIS technology. The results revealed the following: 1) the difference in water demand of spring maize was over 22 mm among wet, normal, dry, and extremely dry years, and the irrigation demand indices were 0.37, 0.44, 0.50, and 0.55, respectively. 2) Water shortages for spring maize first increased and then decreased from the northeast to the southwest, and the water shortage in the same hydrological year was higher in the west and lower in the east. The water requirements of spring maize increased gradually from the northeast to the southwest, and water requirements in the same hydrological year were higher in the southwest and lower in the northeast. Water requirements and shortages increased with increasing drought degree in the same region. The western region of the study area had the highest degree of dependence on irrigation, requiring long-term irrigation to ensure spring maize production. The planting structure should be adjusted appropriately and an inadequate irrigation system should be adopted to ensure water supply to spring maize during the critical period of water demand. Water requirements for spring maize were higher in eastern Liaoning, whereas water shortage and irrigation demand indices were lower than average because of abundant rainfall. Spring maize planting areas can be moderately expanded to maximize the use of rainfall and increase crop production and income.