Rainwater harvesting for supplemental irrigation to enhance crop productivity under rainfed conditions: A case study of north eastern ghats zone of Odisha

Rainwater harvesting-cum-supplemental irrigation is an important strategy to enhance crop water productivity under rainfed conditions. This study was conducted to assess efficacy of farm pond in harvesting rainwater and utilizing it for irrigation to okra-radish cropping sequence during 2018-19 and 2019-20 at Phulbani, Odisha. In this study, runoff harvested from a catchment area of 0.5 ha and stored in farm pond was quantified. Also, seepage and evaporation losses from the farm pond were determined along with computation of area that could be irrigated from the stored water. Three irrigation treatments were considered, namely, T₁ - life-saving irrigation to okra and one protective irrigation of 5 cm to radish, T₂ -life-saving irrigation to okra and two protective irrigations of 5 cm each to radish, T₃ - control without any protective irrigation. Rainwater harvesting potential of the study area varied from 8.3% to 8.9% of rainfall. Evaporation and seepage losses from the pond varied from 30.6% to 27.4% and from 18.21% to 17.4% during 2018 and 2019, respectively. About 26.35% and 24.8% of the harvested rainwater was utilized for providing life-saving irrigations to 0.4 ha cropped area during Kharif and Rabi seasons in 2018 and 2019, respectively. Treatment T₂ consisting of one life-saving irrigation to okra and two irrigations to radish resulted in the highest okra equivalent yield (OEY) of 10,156 kg ha^-1 and 10,228 kg ha^-1 during 2018 and 2019, respectively. Crop water productivity was found to be the highest, i.e., 0.63 and 0.632 kg m-3 during 2018 and 2019, respectively for treatment T₂. Therefore, pond water can be used for providing life-saving irrigation to the vegetable crops, as it resulted in higher returns due to increased crop yields. Rainwater harvesting provides farmers an opportunity to go for second crop in Rabi season.