Delayed rainfall diminishes the positive response of soil respiration to warming

Background Soil respiration (R s ) is a highly sensitive and consequential process in terrestrial ecosystem carbon (C) cycling under global change scenarios, particularly warming and altered precipitation patterns. However, how warming and delayed rainfall interact to influence R s and its components remains poorly understood. Methods Here, we combined a field factorial manipulation experiment with δ 13 C natural abundance partitioning and a complementary meta‐analysis to quantify responses of R s and its components in grassland ecosystems. Results We found that warming and delayed rainfall exerted contrasting effects on R s , with warming overall tending to stimulate R s and delayed rainfall tending to suppress it. Crucially, results from the field experiment indicated that the strong negative effect of delayed rainfall could additively diminish or even reverse the positive net response of R s to warming, a pattern further supported by the meta‐analysis, revealing an average 9.7% reduction in R s under their combined effects. This interaction was most pronounced during the mid‐growing season, as warming exacerbated drought stress under delayed rainfall, potentially shifting the ecosystem from temperature limitation to water limitation. Moreover, such warming‐induced drought drove differential responses of respiration components, where autotrophic respiration showed higher sensitivity than heterotrophic respiration. Conclusions Our findings demonstrate that delayed rainfall diminishes the warming‐induced stimulation of R s by exacerbating moisture deficits. Consequently, ignoring the interaction between warming and delayed rainfall may lead to overestimations of positive soil carbon–climate feedback under future compound hot–dry scenarios.