Crop-Specific Weather–Yield Associations in Irrigation-Intensive Oasis Agriculture: Evidence from Cotton and Maize in Xinjiang, China

Weather–yield relationships in arid agricultural regions are shaped jointly by temperature and precipitation exposure, irrigation conditions, crop choice, and management under water constraints. This study combines county-level cotton yield and maize grain-yield data for Xinjiang, China, from 2000 to 2020 with daily meteorological station records assigned to county-level weather exposures. We estimate two-way fixed-effects models that include temperature degree-day indicators and a quadratic precipitation term to examine crop-specific weather–yield associations in irrigation-intensive oasis agriculture. The baseline two-way fixed-effects estimates indicate that a 100 °C d increase in growing degree days is associated with a 2.85% increase in cotton yield and a 1.88% decrease in maize yield. For cotton, the baseline and common-trend specifications indicate a convex precipitation–yield association, with an estimated turning point of 141.07 mm (95% CI: 27.75–225.63 mm), while the pattern is less stable under prefecture-by-year fixed effects. Maize yield is more consistently negatively associated with growing-season heat accumulation. Post-2010 interaction terms indicate crop-differentiated changes in heat sensitivity, consistent with different temporal evolution of weather–yield associations across cotton and maize. Overall, the results show that climate-risk assessment in irrigation-intensive arid agriculture should distinguish between crop types, precipitation regimes, and the management conditions under which weather exposure is translated into yield outcomes.