Spatiotemporal variations in water requirements of soybean across China

【Objective】 The cultivation of soybeans has increased in China and to assess the potential influence of this on agricultural water usage, we analysed the spatiotemporal variation in its water requirements across the whole country. 【Method】 The analysis was based on meteorological data measured from 1971 to 2020 in main soybean production regions. Water requirement of soybean in each region was calculated using crop coefficient and the potential evapotranspiration. The Mann-Kendall trend test method and the rescaled range method were used to analyze spatiotemporal variation in water requirement and water deficit of the soybean, for both current conditions and projected future scenarios. 【Result】 The average water requirement and water deficit of soybeans during their growth period across the country were 382 mm and 111 mm, respectively. However, these values exhibited significant spatial variability. The arid and semi-arid areas in the North, as well as the Qinghai-Tibet Plateau and the Loess Plateau are particularly susceptible to drought and water shortage. The average water deficit across various regions in the country ranged from 30 mm to 344 mm. Drought and water shortage have been worsening in some regions, which include the Eastern arid and semi-arid regions in Northern China, the Southern Northeast plain, the Western Huang-Huai-Hai plain, the Southern Yunnan-Guizhou plateau, the Southern region in the Northeast plain, the Western Huang-Huai-Hai plain, the Southern Yunnan-Guizhou plateau, specially in the Southern Yunnan-Kweichow Plateau. Furthermore, drought and water shortages in the Eastern arid and semi-arid regions in Northern China, the Southwest of the Yunnan-Guizhou plateau, and the Western Qinghai-Tibet Plateau are expected to Worsen. A potential water shortage crisis is anticipated in the Western Huang-Huai-Hai region, the Southeast of the Yunnan-Guizhou plateau, and the Northern, middle and lower reaches of the Yangtze River. 【Conclusion】 Our analysis indicates that drought and water shortage for soybean production in the South of the Northeast Plain, Western Huang-Huai-Hai Plain, and the middle and lower reaches of the Yangtze River are predicted to intensify. Therefore, enhancing water-saving measures is essential for sustaining water resource use in these regions for soybean production.