Seasonal drought during the soybean growth period and agricultural water stress in southern China eased in the context of global warming

Seasonal drought poses significant risks to agricultural productivity in humid areas. However, research on crop water requirement (CWR) and irrigation water requirement (IWR) under such conditions remains limited, particularly in the Yangtze River Basin—a climate-sensitive monsoon area with frequent precipitation mismatches. In this study, soybean water requirements (SWR) in the middle reaches of the Yangtze River Basin were investigated on the basis of meteorological data from 1961 to 2021. The daily Standardised Precipitation Evapotranspiration Index was used to assess drought conditions throughout the growth period. Moreover, the effects of drought on SWR at different growth stages were evaluated. Used the Random Forest combined with SHAP to explain the effect of meteorological factors. The impacts of meteorological factors on SWR under different drought and wet scenarios were subsequently analysed via the GeoDetector model. The results revealed that the multiyear average CWR and IWR of soybeans were 433.82 and 356.81 mm, respectively, and decreased with trends of 0.197 and 0.235 mm/year, respectively. The regional drought characteristics exhibited a decreasing trend, with light (46.40 %) and moderate (33.68 %) droughts dominating. The rapid growth and mid-season stages exhibited the highest vulnerability to drought ( r < -0.4). Net radiation consistently had the strongest effect on spatial heterogeneity ( q > 0.7) in SWR. The wet scenario was mainly driven by net radiation-temperature, while the others were driven by net radiation-vapour pressure deficit. The study results could provide crucial insights for formulating drought mitigation strategies and achieving efficient agricultural water management. • Soybean water requirements exhibited a decreasing trend from 1961 to 2021. • Over the past 61 years, droughts during the soybean growth period have eased. • The soybean was affected primarily by seasonal drought at the mid-season stage. • Among the meteorological factors, net radiation yielded the most significant impact. • An analytical framework for seasonal drought-water requirements was established.