Estimation of yield reduction and scheduling irrigation in greengram under changing climate of North Interior Karnataka

Abstract

Greengram is one of the major legume predominately cultivated in North Interior Karnataka (NIK). The simulation study using CROPWAT aimed to quantify yield reduction under rainfed condition and schedule irrigation in greengram variety DGGV- 2. Crop management input in the model was based on the recommended practices of UAS, Dharwad across four dates of sowing from 7th to 28th June at weekly interval on black clay and red loamy soils. The simulated outputs were analyzed at decadal intervals for both past (1991-2020) and projected climate (2021-2050). The spatial distribution of yield reduction on both the soils under past and projected climate for all the 12 districts of NIK was interpreted using ArcGIS software. On both black clay and red loamy soils, average number of irrigation increased by 0.3 and 1.2 under projected climate, respectively, compared to past climate. Yield reduction in rainfed condition on black clay and red loamy soils under projected climate increased by 6.6 % and 3.3 %, respectively, compared to past climate. Sowing late i.e., on 28th June under projected climate (2021-2050) simulated the lowest yield reduction (rainfed) and require fewest irrigations across 12 districts of NIK.