Vol. 12, Special Issue 10 (2023)

Author(s):
M Manikandan, N Anandaraj, M Rajeswari, S Manoharan, V Sanjivkumar, G Guru, K Baskar and G Ravindracharry

Abstract:
Uncertain dry periods and rainfall shortfalls pose serious obstacles to rainfed crop production. In-situ rainwater harvesting methods are employed within the farm to retain soil moisture and meet crop needs. However, these methods prove insufficient during prolonged dry periods lasting 2-3 weeks. Supplemental irrigation through ex-situ rainwater harvesting offers a solution to mitigate the impact of dry spells on crop growth and reduce yield loss. In semi-arid regions like the Vertisols tract of Kovilpatti, India, Rainfed crops are largely cultivated during the North East Monsoon (NEM) season occurring from October to December and typically brings about 400 mm of rainfall. Monsoon failures and prolonged dry spells frequently occur in these areas. A continuous long-term research study conducted between 2011 and 2021 at the black soil farm of Agricultural Research Station in Kovilpatti, Tamil Nadu, aimed to assess runoff potential, losses, and the feasibility of supplemental irrigation (SI) from a farm pond for rainfed cotton production. By analyzing runoff-causing rainfall and runoff generated from one-hectare catchment area, the runoff coefficient of 0.24 was determined. On average, a quantity of 250 m³ of water can be collected in a farm pond. This amount is sufficient for a single application of supplemental irrigation (SI) on an area of 0.4 hectares at a depth of 50 mm. This study documented a yield increase ranging from 12.7% to 17% and a rainwater use efficiency of 1.52 to 3.13 kg/ha/mm in cotton through the implementation of SI during critical moisture stress periods. The combined use of in-situ and ex-situ rainwater harvesting at the farm level, along with modern micro irrigation, will enhance the productivity of rainfed crops.