D.K. Singh, Zenab Akhtarb, Shilpi Gupta and Ashish Srivastava
Abstract
Field experiments were conducted at G.B. Pant University of Agriculture and Technology, Pantnagar, India during rainy season 2012 and 2013 to explore possible outcomes of sustainable production of organic basmati rice in terms of productivity, water use efficiency and methane emission reduction in mollisols of Uttarakhand, India. Six treatments viz., conventional transplanting with Sesbania green manuring (GM) + vermicompost (VC), conventional transplanting with Farmyard manure (FYM) + VC, system of rice intensification (SRI) with FYM, direct seeded rice (DSR) with FYM, farmers practice organic control (FYM @ 10 t /ha) with continuous flooding and farmers practice chemical control recommended NPK (N70P40K30) was taken in randomized block design (RBD) with three replications. However, only four treatments viz., GM + VC, FYM + VC, SRI and chemical control were considered to quantify methane flux. Traditional basmati rice variety Type-3 popularly known as Dehraduni Basmati was taken for study. Flux measurements of methane were done by Flame Ionization Detector (FID) at different stages of crop growth. Under organic amendments green manuring with sesbania increased the growth, yield parameters, and yield of rice due to high nitrogen accumulation and greater release of nitrogen during both the years. Maximum CH4 flux was observed at panicle initiation stage (55 DAT). During the entire crop growth period, the treatments GM + VC, FYM + VC, SRI and chemical control produced an average CH4 flux of 20.19, 13.00, 9.83 and 5.53 mg m-2 h-1, respectively. This shows that among the nutrient sources, CH4 emission was higher in organically fertilized plots as compared to chemically fertilized with urea at initial stages, however, at later stages, not much variation was observed in CH4 emission for different nutrient sources. Even with in organic system less CH4 was emitted from SRI field where water was maintained alternate wetting and drying system.