Abstract Growing season rainfall variations strongly govern crop productivity, especially in monsoonal agricultural systems such as those in the Indian subcontinent. The optimum rainfall threshold (ORT), defined as the rainfall amount resulting in maximum yields, is a critical yet underexamined factor in achieving stable and high agricultural productivity. Here, by integrating 28 years (1990–2017) of district‐level observations of crop yield in India with diverse rainfall indices, we show that for every 1% (17 mm) increase in seasonal rainfall beyond the ORT, yield declines by 0.20% (0.67 kg ha −1 ) for cotton and 0.11% (1.33 kg ha −1 ) for soybean. Moreover, excess rainfall beyond the ORT causes yield losses comparable to those from equivalent rainfall deficits. Crop yields are more sensitive to rainfall intensity on rainy days than to the frequency of those days, highlighting the greater role of intra‐seasonal rainfall dynamics. The sensitivity to rainfall varies by crop and region, with rice and groundnut showing the strongest rainfall‐yield associations among the eight crops studied. Model‐based projections under future climate scenarios suggest substantial yield declines in India by the mid‐century, driven by anticipated increases in monsoon‐season rainfall. These findings highlight the importance of incorporating ORT‐based metrics into agricultural planning and food security strategies under a changing climate.
Maiti et al. (Mon,) studied this question.