Methane emission from rice fields at Cuttack, India

Methane (CH4) emission from rice fields at Cuttack (State of Orissa, easter n India) has been recorded using an automatic measurement system (closed ch amber method) from 1995-1998. Experiments were laid out to test the impact of water regime, organic amendment, inorganic amendment and rice cultivars. Organic amendments in conjunction with chemical N (urea) effected higher C H4 flux over that of chemical N alone. Application of Sesbania, Azolla and compost resulted in 132, 65 and 68 kg CH4 ha(-1) in the wet season of 1996 when pure urea application resulted in 42 kg CH4 ha(-1). Intermittent irrig ation reduced emissions by 15% as compared to continuous flooding in the dr y season of 1996. In the wet season of 1995, four cultivars were tested und er rainfed conditions resulting in a range of emissions from 20 to 44 kg CH 4 ha(-1). Application of nitrification inhibitor dicyandiamide (DCD) inhibi ted while Nimin stimulated CH4 flux from flooded rice compared to that of u rea N alone. Wide variation in CH4 production and oxidation potentials was observed in rice soils tested. Methane oxidation decreased with soil depth, fertilizer-N and nitrification inhibitors while organic amendment stimulat ed it. The results indicate that CH4 emission from the representative rainf ed ecosystem at the experimental site averaged to 32 kg CH4 ha(-1) yr(-1).