Improving water productivity of sprinkler-irrigated cumin through deficit irrigation in arid areas 后印本

摘要: Integrating sprinkler with deficit irrigation system is a new approach to improve crop water productivity and ensure water and food security in arid areas of India. This study undertook a field experiment of sprinkler-irrigated cumin (variety GC-4) with a mini-lysimeter setup at an experimental research farm in Jodhpur, India during 2019–2022. Four irrigation treatments T1, T2, T3, and T4 were designed at irrigation water/cumulative pan evaporation (IW/CPE) of 1.0, 0.8, 0.6, and 0.4, respectively, with three replications. Daily actual crop evapotranspiration (ETc) was recorded and weekly soil moisture was monitored over the crop growth period. Quantities of applied water and drainage from mini-lysimeters were also measured at every irrigation event. Yield of cumin was recorded at crop maturity. Furthermore, change in farmer’s net income from 1-hm2 land was computed based on the cost of applying irrigation water and considering yield variations among the treatments. Results indicated the highest mean seasonal actual ETc (371.7 mm) and cumin yield (952.47 kg/hm2) under T1 (with full irrigation). Under T2, T3, and T4, the seasonal actual ETc decreased by 10.4%, 27.6%, and 41.3%, respectively, while yield declined by 5.0%, 28.4%, and 50.8%, respectively, as compared to the values under T1. Furthermore, crop water productivity of 0.272 (±0.068) kg/m3 under T2 was found relatively higher in comparison to other irrigation treatments, indicating that T2 can achieve improved water productivity of cumin in arid areas at an optimum level of deficit irrigation. The results of cost-economics indicated that positive change in farmer’s net income from 1-hm2 land was 108.82 USD under T2, while T3 and T4 showed net losses of 5.33 and 209.67 USD, respectively. Moreover, value of yield response factor and ratio of relative yield reductions to relative ETc deficits were found to be less than 1.00 under T2 (0.48), and more than 1.00 under T3 (1.07) and T4 (1.23). This finding further supports that T2 shows the optimized level of deficit irrigation that saves 20.0% of water with sacrificing 5.0% yield in the arid areas of India. Findings of this study provide useful strategies to save irrigation water, bring additional area under irrigation, and improve crop water productivity in India and other similar arid areas in the world.