Irrigation scheduling of crops under the influence of shallow groundwater table

This study aims to develop irrigation schedules for Indian mustard, wheat, pea, and maize by evaluating root zone soil moisture dynamics under the influence of a shallow groundwater table (SGT) with capillary rise. Field-based Lysimeter experiments conducted at NIT Hamirpur, Himachal Pradesh, under sub-humid subtropical conditions were combined with a numerical model to capture soil moisture variations. The model showed strong agreement with observed data (R2 = 0.70–0.85; NSE = 0.72–0.85; MBE within ±0.05), confirming its predictive reliability. Irrigation schedules were derived for crop root zones with SGT (CRZSGT) and compared with gravity drainage (CRZGD). The number of irrigation events decreased from 6 to 4 for Indian mustard and wheat, from 8 to 6 for pea, and from 3 to 2 for maize. This resulted in water savings of 30.5%, 36.8%, 25%, and 33.3% for the respective crops. Crop yields were consistently higher under CRZSGT, with percentage increases of 8%, 12%, 10%, and 3% in Indian mustard, wheat, pea, and maize, respectively, compared to CRZGD. The findings demonstrate that incorporating SGT into irrigation scheduling can save water while sustaining or slightly enhancing crop yields, offering a practical framework for water-scarce regions.