SIMULATION OF RICE WATER DEMAND UNDER CONVENTIONAL AND MODIFIED WATER MANAGEMENT PRACTICES USING DNDC MODEL IN BHAVANISAGAR BASINJ. Kavitha Mary, K. Senthilraja, R. Anbhazhagan and A.P. Ramaraj
Rice-DNDC (DeNitrification Decomposition) model is mainly used to calculate methane emission from rice ecosystem. It also calculates the water requirement and uptake by plants. The present study was carried out to simulate rice water demand for the year 2013 and 2014 under different management practices (conventional and 10 days Mid Season drainage in the 45th DAT and 65th DAT). For this study simulated weather parameters for the year 2013 and 2014, soil properties and farming practices for Bhavanisagar basin is given as input for Rice-DNDC model. The results show that precipitation will be calculated as 891.4 mm for 2013 and 724.2 mm for 2014. Irrigation water requirement for conventional cultivation is 2245 mm water and 1945 mm for mid-season drainage for three consecutive paddy crops. Mid-season drainage will reduce the water requirement and methane emission from rice ecosystem because decomposable organic matter was decomposed under aerobic conditions. In the present investigation water demand is similar for both conventional and modified irrigation method (768.66 mm for 2013 and 888.6 mm for 2014). Water uptake is reduced in mid-season drainage (656.05 mm, 715.88 mm) than conventional (707.51 mm, 826.55 mm) in 2013 and 2014 respectively. Water stress is negligible in both conventional and mid-season drainage (2.95 and 2.96 mm respectively). Hence mid-season drainage is a water saving method which also reduces the methane emission from paddy ecosystem.
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