Global methane emission from rice-paddies: excellent methodology but poor extrapolation

Abstract

Methane emission from rice paddies would require a source of carbon as a substrate and a reducing soil environment. The maximum methane production from glucose, presuming it as a source of carbon, was estimated on the basis of known micro-biochemical reactions. The total biomass of rice paddies from the various regions was estimated using grain yield and biomass partition coefficient (Harvest Index). The relation of biomass and methane emission was used as reported earlier for estimating methane emission from rice paddies. The maximum global methane emission from rice paddies was estimated 7.08x10¹² g as against 110x10¹² g and 60x10¹² g reported by IPCC in 1990 and 1994, respectively. The need for identifying new sources of methane is emphasized, and the limitations of experimental methodology highlighted.