Comparative evaluation of water budgeting parameters under different rice (Oryza sativa L.) cultivation methods

Water budgeting studies under different rice cultivation methods provides an insight into the amount of water used by the plant and percolated below the root zone for judicious water management. To undertake this study, a field experiment was conducted to estimate different soil water balance parameters under three rice (Oryza sativa L.) cultivation methods viz. Direct Seeded Rice (DSR), System of Rice Intensification (SRI) and Conventional Puddled Rice (CPR). The experiment was conducted during kharif 2013 and kharif 2014 season at research farm of Indian Council of Agricultural Research-Indian Agricultural Research Institute, New Delhi, India. In this study, the rainfall and irrigation depth, Crop Evapotranspiration (ETc), percolation beyond root zone of the crop and surface runoff during the crop growth period were accounted in water budgeting. It was observed that the percolation be-yond root zone of the crop was the highest under CPR method amounting 963 mm and 831 mm, which was about 55% and 58% of total water applied during 2013 and 2014, respectively. However, the percolation beyond root zone of the crop was the lowest under DSR method of rice cultivation amounting 367 mm and 332 mm which was 43% and 39% of total water applied during 2013 and 2014, respectively. Water loss through Etc was around 30% of total water applied in all three cultivation methods for year 2013. However, it was 59%, 46% and 43% of total water ap-plied for DSR, SRI and CPR, respectively in the year 2014.This indicates more effective utilization of total applied water in the year 2014.The study highlighted that water loss through deep percolation beyond root zone is the major factor contributing to the high water requirement in CPR and SRI methods compare to DSR method. Moreover, different soil water balance components computed in this study will be helpful for estimation of irrigation water requirement in the rice growing areas of the agro-climatic region VI (Trans-gangetic Plains) of India.