Irrigation Timing Tolerance in Staple Crops: Implications for Food Security under Climate Variability

Abstract

This paper reports on a forty-year field study — one of the longest of its kind — examining how three of the world's most important food crops respond to changes in irrigation timing. Working across smallholder farms in West Bengal, India, between 1985 and 2025, we tracked 327 individual plants of paddy rice, wheat, and potato through hundreds of growing seasons. What we found was, in some ways, exactly what experienced farmers have long suspected: crops appear to care not only about how much water they receive, but about when.
After two to three weeks on a consistent watering schedule, plants seemed to anticipate their irrigation — showing physiological signs of preparation before water even arrived. When we disrupted those schedules abruptly, yields fell by 15 to 35 percent, even when the total amount of water delivered remained exactly the same. Gentle, gradual schedule transitions, by contrast, produced almost no disruption at all.