Climate change and economic policy dominate soybean cultivation in china in recent decades of the 21st century

Over the past two decades, despite significant fluctuations in China's soybean planting area, high-resolution assessments quantifying the spatially heterogeneous and nonlinear impacts of compounding economic, climatic, and policy drivers remain scarce. To fill this gap, this study uses satellite remote sensing data (2000–2022) to map 1 km gridded soybean areas across China’s three main producing regions: the Northeast China Plain (NEP), Huang-Huai and Middle-Lower Yangtze Plains (HH-MLYP), and Sichuan Basin (SCB). Integrating yield and cost‒price data, we calculated the comparative economic benefit (CEB) between soybean and maize. A random forest model with SHapley additive explanations (SHAP) quantified the contributions of CEB, climatic, and topographical variables. Results revealed that CEB, growing season precipitation, and growing degree days were the most influential drivers, explaining 14.88%, 14.47%, and 13.70% of area variation, respectively. These impacts exhibit strong spatial heterogeneity: economic factors dominate in the NEP, whereas climate is more critical in the HH-MLYP and SCB. Subsidy policies effectively expanded planting in the NEP, despite diminishing marginal effects. These findings provide a scientific basis for optimizing planting strategies and designing targeted subsidies.