Abstract:

The water footprint of grain production is an effective method for assessing the regional agricultural water resource situation. As a typical ecologically fragile area in the northwest region of China, Yulin city had been facing severe competition for water use among industry, agriculture, and residents, with intensified production, living, and ecology water resource pressures. Analyzing the effects of crop structure adjustment in Yulin city from the perspective of the water footprint of grain production is crucial for achieving efficient integration of regional water resources and agricultural production. In this study, the authors employed the food security index and crop water footprint theory to quantify the crop structure and water use in Yulin city from 2000 to 2020 with the perspective of the production water footprint. Additionally, an agricultural benefit evaluation system was developed using the entropy weight method to analyze the regional grain yield and water-saving benefits. The results indicated that (1) from 2000 to 2020, the planting structure of grain crops in Yulin city underwent significant changes, with an increase in the sowing area of corn and tubers becoming the dominant crops. The total output of major crops’ significantly increased from 55.89×10⁴t to 212.01×10⁴t, and the grain self-sufficiency rate also increased from 4.29% to 13.74%. (2) The blue-water footprint slightly increased during the grain crop planting structure adjustment. During the study period, the water footprint per unit mass of major grain crops had decreased, with the lowest blue water footprint per unit mass of corn at 0.21m³·kg⁻¹. At the county level, the blue-to-green water ratio was predominantly characterized by blue water being no more than green water. (3) During the study period, the grain yield, water-saving, and comprehensive benefits of agriculture had significantly increased. The comprehensive agricultural benefits had improved, with the northern six counties generally experiencing higher benefits than the southern six counties. The authors found that the planting structure adjustment had effectively ensured regional food security, with a small increase in the blue water footprint, sustaining the security of regional groundwater and surface water resources. This adjustment optimized regional water resource utilization while enhancing the benefits of grain yield and water savings. To ensure the coupling and sustainable use of cultivated land and water resources in the future, it is essential to improve cultivated land quality by focusing on “land use structure, water use structure, and planting structure”. Additionally, it is crucial to promote drip irrigation, sprinkler irrigation, and cultivating drought-resistant crops in the northern six counties, while developing “four-in-one” rainwater replenishment irrigation in the southern six counties, combined with biological coverage measures to enhance the soil's water retention and moisture retention capacity. 

Key words: Water footprint, Cropping structure, Water resources, Food production, Yulin city