N2O emissions of India: an assessment of temporal, regional and sector trends

Abstract

This paper estimates the national level trend of India’s N2O emissions from 1985–2005 and detailed sub-regional (594 districts) level and sector emissions for the year 2005. N2O emissions are estimated using the latest methodologies (IPCC 2006), disaggregated activity data and indigenized emission factors. The estimates show that India’s N2O emissions have grown from 144 Gg in 1985 to 267 Gg in 2005 exhibiting a compounded annual growth rate of 3.1%, which has been gradually declining from 4.7% over 1985–1990 to 2.4% over 2000–2005. N-fertilizer application contributed most to N2O emissions, a 49% share in 2005 compared to 40% in 1985. Sub-regional (district-level) distribution of N2O emissions showed rising mean and spread over the years, with average emissions per districts increasing from 305 ton N2O per year in 1990 to 450 tons in 2005. The main reason being increased use of N-fertilizer. However crop selection plays an important role in N2O emissions and there are crops providing high economic returns but low N-fertilizer requirements. Agriculture sector could contribute considerably to GDP even with very low N2O emissions. Indian agriculture practices vary widely in input applications and crop yields across states. The gradual transition from traditional to modern agriculture over past two decades has enhanced the intensity of inputs like N-fertilizer. A simple correlation based on 1985–2005 trends shows that, ceteris paribus, a 10% increase in total crop production is accompanied with a 12.4% increase in N-fertilizer application and a 9.7% increase in total N2O emissions from India.