Rice area mapping and methane emission pattern in the Cauvery Delta region of Tamil Nadu

Rice is extensively grown on larger scales for human food consumption and animal fodder purposes. Rice paddies are a significant source of methane, a potent greenhouse gas contributing to climate change. Accurate estimation of methane emission was pivotal for comprehending environmental impacts and formulating effective mitigation strategies. Synthetic Aperture Radar (SAR) data operating in the microwave region classifies the crop area since it is sensitive to biophysical parameters, and classification is based on the backscatter coefficient. The rice-growing area was delineated using MAPscape-RICE software during kharif 2023 for the Cauvery Delta districts of Tamil Nadu. The delineated rice area was validated against ground truth data and had an overall accuracy of 92.5% with a kappa value of 0.85. The experiment was carried out on CH4 emission patterns in rice fields with different planting, irrigation, and fertilizer application practices. Methane emissions peaked during the panicle initiation stage across direct-seeded and transplanted rice, with higher emissions observed under organic manure application. The alternate wetting and drying (AWD) practices significantly reduced the methane emissions by 37% compared to continuous flooding. Whereas, the direct-seeded method of planting (DSR) reduced emissions by 25% compared to conventional transplanting practices.