Evaluating the comprehensive effects of planting winter wheat in the groundwater depletion regions in the North China Plain

The traditional annual double cropping system of winter wheat and summer maize in the North China Plain (NCP) can take the full advantage of regional climate resources, and has played an important role in maintaining national food security. However, high winter wheat production depends on irrigation, which is one of the leading factors for groundwater over-exploitation in the NCP. With the implementation of the national groundwater extraction restriction policy, how to develop winter wheat in groundwater over-extraction areas is becoming an important issue. Based on long-term field experimental data and literatures, this paper discussed aspects such as reducing soil evaporation loss during fallow period, brackish water resources utilization, deficit irrigation to improve quality, and effective cover formation in winter and spring seasons by planting winter wheat. The production of winter wheat in the groundwater depletion regions in the NCP would involve a change from the traditional practice of applying adequate irrigation water for high yield to using limited irrigation for higher quality and higher water use efficiency. The planting of winter wheat can reduce soil evaporation and fully use the rainfall resources during winter and spring seasons. Winter wheat can also form an effective coverage to reduce soil erosion and green the rural areas. By applying reduced irrigation based on the irrigation water availability in a region, winter wheat can still maintain a stable yield due to its deep root characteristics which can efficiently absorb the deep soil water stored during the summer rainy season. Under reduced irrigation, the quality of winter wheat can be improved, which provides the opportunity to grow high-quality winter wheat in the NCP. In the low plain of the NCP, where shallow saline water is abundant, irrigation for winter wheat by fresh water can be replaced by the shallow saline water. Growing winter wheat based on the irrigation water availability in the NCP has the benefits of wind erosion protection, beautification of the rural environment, and meeting regional food security.