Stage-specific drought impacts and the mitigating role of irrigation on maize yield: evidence from satellite remote sensing

In the context of global warming, frequent agricultural droughts pose a severe threat to food security. Henan Province, as a primary maize-producing hub in China, is highly susceptible to these extreme climate events. Leveraging a comprehensive dataset combining county-level meteorological indicators, satellite remote sensing observations, and agricultural statistics spanning 2013 to 2022, this study investigated the stage-specific impacts of drought on maize yield and the mitigating role of irrigation investment. To identify the “critical windows” of crop vulnerability, we segmented the maize growth cycle into five distinct phases: sowing, emergence, jointing, tasseling, and maturity. Employing a two-way fixed effects model, the findings indicated that agricultural drought had a significant negative impact on yield. A one-unit increase in drought severity reduced output by 1.46 t/ha. The analysis revealed pronounced heterogeneity, identifying tasseling and maturity as the most vulnerable “critical windows,” where yield losses reached 0.79 t/ha and 0.78 t/ha, respectively. Crucially, interaction analysis demonstrated that irrigation served as vital “climate insurance,” significantly attenuating these marginal losses. Satellite remote sensing evidence via Normalized Difference Vegetation Index (NDVI) mediation analysis substantiated that irrigation maintains crop physiological activity and suppresses the transmission of drought shocks during sensitive phenological phases. These results provide a scientific basis for enhancing climate resilience through precision irrigation during reproductive stages, offering a crucial hydrological foundation for broad-scale agricultural strategies like the Integrated Soil-Crop System Management framework to stabilize grain production.