Grain Expansion in China's Drylands Secures Food but Intensifies Environmental Trade-Offs

Drylands are increasingly crucial for global food supply, and grain cultivation there continues to expand. Newly cultivated croplands in these regions are often assumed to be biophysically marginal and low yielding. However, the food-security benefits, environmental costs, and associated trade-offs of this expansion remain insufficiently quantified. Here, we assessed maize, wheat, and rice expansion across China's drylands (2000–2019) by harmonizing 1-km crop maps, estimating grid-scale expected yields (under typical local production conditions) with machine-learning models, and coupling these estimates with a process-based crop water-demand model and gridded fertilizer and pesticide data sets. Results show that drylands accounted for a significantly increasing national share of all three crops, driven primarily by maize and rice expansion. Crop expansion areas exhibited competitive expected yields, with ∼60% exceeding stable-area benchmarks. However, this competitive performance was accompanied by higher input burdens. Relative to stable croplands, median fertilizer inputs increased by 11.1%–18.1%, pesticide inputs by 3.2%–15.5%, and blue-water demand by 3.2%–11.7%, while their use efficiencies declined for most crops. Overall, 89.4% of crop expansion areas exhibited at least one high-input indicator, with 58.1% facing double or triple burdens. These findings highlight spatially heterogeneous yield-input trade-offs, suggesting that yields in these expansion areas are maintained largely through elevated inputs. Such input-dependent yields can trigger a self-reinforcing “high-yield trap,” where competitive yields incentivize further expansion and intensification in water-limited regions. Future dryland agriculture must therefore move beyond aggregate production growth toward differentiated zoning centered on yield benefits, input efficiency, and resource sustainability.