Increasing Rainfed Pigeonpea and Groundnut Water Productivity through Supplemental Irrigation from Farm Pond in Micro-Watershed of Raichur

Rainwater management is the most critical component of rainfed farming. Successful production of rainfed crops largely depends on how efficiently soil moisture is conserved in-situ or the surplus runoff is harvested in farm ponds, stored and recycled for supplemental irrigation. A field experiment was conducted to find out the catchment-storage-command relationship for enhancing water productivity in micro-catchment of University of Agricultural Sciences (UAS) campus, Raichur. A square shaped (trapezoidal section) farm pond of size 18 x 18 m top width, 10x10 m bottom width and 2.70 m depth was excavated. The total capacity of the pond was 547.0 m³. The catchment and command area were delineated as 8 and 1 ha respectively. In 2019, there were six runoff events. The highest sediment yield during the season was calculated by collecting the runoff samples from the runoff events, and it was 0.40 t/ha against the rainfall of 113.00 mm and runoff volume of 2985.50 m³. In 2020, the highest sediment yield recorded was 0.358 t/ha against the rainfall of 83.60 mm and runoff of 33.84 mm with runoff volume of 1596.40 m³. Supplemental irrigation (SI) was provided in first year to pigeonpea crop during pod filling stage and higher yield of 12.27 q/ha was recorded as compared to without supplement irrigation (11.20 q/ha). Higher rain water use efficiency (RWUE) of 1.85 kg/ha-mm was obtained under supplemental irrigated as compared to without supplement irrigation (1.76 kg/ha-mm). Higher net returns of Rs. 39120 and benefit cost ratio of 2.13 was recorded in SI field as compared to without SI. During second year, the SI for groundnut was provided during pod development stage and higher yield was recorded (15.26 q/ha) as compared to without SI (13.15 q/ha). Higher RWUE of 2.75 kg/ha-mm was recorded under SI as compared to without SI (2.57 kg/ha-mm). Higher net returns of Rs. 41378 and benefit cost ratio of 2.05 was recorded with SI as compared to without SI. In semi-arid regions of Karnataka, runoff water harvesting in a pond and using the collected water through SI could be a promising option for enhancing the productivity of pigeonpea and groundnut.