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Authors
Affiliations
1 Department of Science and Humanities, Vel Tech High Tech Dr. Rangarajan and Dr. Sakunthala Engineering College, Avadi, IN
Source
Biometrics and Bioinformatics, Vol 3, No 4 (2011), Pagination: 184-192
Abstract
Wet land rice paddy ecosystems have been recently identified as a major source of atmospheric methane, which is currently increasing at 7 ppbv yr-1. Methane emission form rice paddies indicate a global source of 60 Tg yr-1. The CH4 emission rates vary significantly with the types of soil, cultivar variety, and cultivar age and water management. The expansion of irrigated cultivation area and new cultivation practices have made rice fields one of most important anthropogenic sources for atmospheric CH4. The CH4 emission from paddy ecosystems is controlled by physical processes (diffusion, ebullition and ventilation) and biological processes (microbial production and consumption). Thus in an effort to reduce uncertainties, in the present study diel variation of methane fluxes were measured from control, Pseudomonas and nemento amended rice cores for 24 hours at an interval of 30 minutes during tillering, reproductive and harvesting stages of growth of rice plants. The CH4 emission rates increased at accelerated rates and were maximum during the early afternoon (14-15 hours, 2.59-9.35 mg/m2) and decreased rapidly and remained constant during night (8.19-7.71 mg/m2). The diel CH4 emission in all the rice cores were lower during the tillering stage (2.18-7.17 mg/m2) and higher at the reproductive stage of the plant (2.59-9.50 mg/m2). This is probably due to higher soil Eh during the initial stage of plant growth. The methane emission was lower in night because low soil temperature at night causes low CH4 production rates. Also higher ambient CO2 concentration in the canopy during night reduces the transport of CH4 through plants. The CH4 emission rates decreases in Nemento amended cores (6.35 mg/m2) than Control cores (8.41 mg/m2) as nemento (product from neem) being nitrification inhibitor reduces CH4 production in soil. The Pseudomonas amended cores resulted in less CH4 emission (6.9 mg/m2) than Control cores as pseudomonas being a denitrifying bacteria helps reducing CH4 emission.
Keywords
Anoxic Soils, Methane Emission, Methane Flux, Methanogenesis, Rice Paddies.
