Abstract

The influence of different sources of nitrogenous fertilisers and seasonal effect on methane emission has been studied at Tamil Nadu Agricultural University Wetland Farm at Coimbatore during kharif and Rahi seasons, 1996. The results showed that fertilised plots recorded higher emission level than unfertilised plots. The emission level in PK alone (without-N) applied plots is higher during both seasons as compared to nitrogen. applied plots. Among the different nitrogenous fertilisers tried, ammonium sulphate was found to reduce the emission level throughout the growing season followed by urea. ammonium chloride and DAP. The sulphur component of ammonium sulphate inhibited methanogenesis in rice rhizosphere. Seasonal variations in methane flux were observed in all treatments. The first peak was observed within 10 days of transplanting and the emission level decreased towards active tillering stage. A second peak of lower magnitude was observed during flowering stage and declined further towards harvest. The magnitude of emission level during Rabi season was two to three fold higher as compared to Kharij season. The emission level varied with texture of the soil. The light textured soils had lower flux level than heavy textured clay soils.

Keywords: Methane emission, Tropical rice soils, Nitrogenous fertilisers, Seasonal variation