Sensitivity of Crop Water Footprints to Planting Dates and Temperature in the Middle Indo-Gangetic Plains, India

Crop water footprint assessment is an emerging area for selecting cropping pattern and best management practices; however, the uncertainties surrounding it have not been fully explored. This study explored the sensitivity of crop water footprint estimates to uncertainties in key input variables. Crop water footprint which included estimation of the green, and blue water footprints of major crops at the district level in the middle Indo-Gangetic plains (MIGP) of India, encompassing Bihar and eastern Uttar Pradesh. Water footprints were estimated for major crops namely rice, wheat, maize (rabi), potato, lentil, and mustard. The one-at-a-time method was applied to assess the sensitivity of the crop water footprint to fractional changes in two specific inputs: planting date with constant growing degree days and temperature. Sensitivity analyses assessed the impacts of shifting planting dates by ±30 days and temperature variations (±20%) on crop water use, yield, and water footprints. The results showed that earlier planting enhances rainfall utilization and yield by up to 17.6 % and 21.1%, respectively, in rainfed rice, whereas delayed planting improves water use efficiency by reducing irrigation demand in irrigated crops such as wheat and maize, with total water footprint reductions up to 5.2% and 0.5%, respectively. Temperature increases generally boost productivity and water use efficiency but elevate blue water (irrigation) requirements, particularly for maize (rabi) and potato. These findings underscore the importance of crop-specific, climate-informed management of planting schedules and irrigation practices to optimize sustainable water use and agricultural productivity in MIGP.