Methane emission from rice fields at Cuttack, India

Methane (CH<SUB>4</SUB>) emission from rice fields at Cuttack (state of Orissa, eastern India) has been recorded using an automatic measurement system (closed chamber 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 CH<SUB>4</SUB> flux over that of chemical N alone. Application of Sesbania, Azolla and compost resulted in 132, 65 and 68 kg CH<SUB>4</SUB> ha<SUP>-1</SUP> in the wet season of 1996 when pure urea application resulted in 42 kg CH<SUB>4</SUB> ha<SUP>-1</SUP>. Intermittent irrigation reduced emissions by 15% as compared to continuous flooding in the dry season of 1996. In the wet season of 1995, four cultivars were tested under rainfed conditions resulting in a range of emissions from 20 to 44 kg CH<SUB>4</SUB> ha<SUP>-1</SUP>. Application of nitrification inhibitor dicyandiamide (DCD) inhibited while Nimin stimulated CH4 flux from flooded rice compared to that of urea N alone. Wide variation in CH<SUB>4</SUB> production and oxidation potentials was observed in rice soils tested. Methane oxidation decreased with soil depth, fertilizer-N and nitrification inhibitors while organic amendment stimulated it. The results indicate that CH<SUB>4</SUB> emission from the representative rainfed ecosystem at the experimental site averaged to 32 kg CH<SUB>4</SUB> ha<SUP>-1</SUP> yr<SUP>-1