Emission of methane and nitrous oxide from Vigna mungo and Vigna radiata legumes in India during the dry cropping seasons

Abstract

Methane (CH₄) and nitrous oxide (N₂O) emission estimates were made for Vigna mungo and Vigna radiata legumes. The affecting soil parameters like redox potential, soil temperature were studied to evaluate CH₄ and N₂O emissions. The CH₄ was negative and N₂O was positive for Vigna mungo, almost throughout the cropping period. The redox potential was more than +100 mV during the entire cropping period with a maximum N₂O flux of 11.67 μg m^–2 h^–1. The raise in soil temperature and the redox potential during harvest further increased the N₂O flux to 18.38 μg m^–2 h^–1. The seasonally integrated flux E(SIF) for CH₄ and N₂O for Vigna mungo was calculated to be –4.06 g.m^–2 and 3.38 mg m^–2 respectively. Similarly E(SIF) values estimated for Vigna radiata cropping season were 0.009 g m^–2 and –7.6 mg m^–2, whereas for the post harvesting period the fluxes were 0.02 g m^–2 and 4.06 mg m^–2 for CH₄ and N₂O respectively. The soil parameters like organic carbon and nutrients such as ammonia, nitrate and nitrite during the cropping season were evaluated. The emission of greenhouse gases (GHG) was also correlated to various physico-chemical parameters of soil.