Estimation of methane emission from rice fields using static closed chamber technique in Tiruchirapalli District

Abstract

Temperature and rainfall (climate) have mostly determined traditional agricultural practices on the Earth. Agriculture is the main source income for the majority of population living in the South and Southeast Asia. Agricultural activities are associated with the emission of greenhouse gases, notably methane (CH4) and nitrous oxide (N2O), which are important for anthropogenically influenced climate change. Among all of atmospheric components, methane (CH4) is a major greenhouse gases (GHG). According to the Intergovernmental Panel on Climate Change (IPCC), the warming forces of CH4 are 25-30 times higher than that of CO2 per unit of weight based on 100-yr global warming potentials (IPCC, 2007). Rice cultivation has been recognized as one of the major anthropogenic source for methane emissions (Li et al, 1999). Methane emission from rice fields is a microbial mediated anaerobic activity, mainly favoured by the flooded condition. In this regard, extensive rice cultivation may become a potential contributor to the enhancement of global warming. Therefore, initiatives to estimate country-specific contributions to the global methane emissions from paddy fields have to be undertaken. Gas samples were collected from the field using static closed chamber technique. The air samples from the sampling bags were analyzed for CO2, CH4 and N2O. The Methane were estimated in a Shimadzu GC-2014 gas chromatograph. The obtained CH4 concentrations were determined by peak area and flux were calculated based on the equation proposed by Rolston et al., 1986) to estimate methane emission. In this study, present the distributions of CH4 emission from rice fields over the Tiruchirapalli District, Field chamber studies registered per day methane emission of 0.43 to 0.49 kg/ha/day and seasonal methane emission 40.8 to 48.5 kg/ha.