A study on GHG emission assessment in agricultural areas in Sri Lanka: the case of Mahaweli H agricultural region

Agricultural activities contribute 7% to Sri Lanka’s economy and account for 20% of the national greenhouse gas (GHG) emissions. The country aims to achieve zero net emissions by 2060. This study was aimed at assessing the present state of agricultural emissions and identifying mitigation strategies. The assessment involved estimating agricultural net GHG emissions from non-mechanical sources in the Mahaweli H region, Sri Lanka, in 2018 using the Intergovernmental Panel on Climate Change (IPCC 2019) guidelines. New indicators were developed to measure emissions for major crops and livestock and used to show the flow of carbon and nitrogen. The region’s agricultural emissions were estimated to be 162,318 t CO(2)eq y(−1), of which 48% was from rice field methane (CH(4)) emissions, 32% from soil nitrogen oxide emissions, and 11% from livestock enteric CH(4) emissions. Biomass carbon accumulation offset 16% of the total emissions. Rice crops exhibited the highest emission intensity of 4.77 t CO(2)eq ha(−1) y(−1), while coconut crop had the highest abatement potential of 15.58 t CO(2)eq ha(−1) y(−1). Approximately 1.86% of the carbon input to the agricultural system was released as carbon-containing GHG (CO(2) and CH(4)), whereas 1.18% of the nitrogen input was released as nitrous oxide. The findings of this study suggest extensive adaptations of agricultural carbon sequestration strategies and increased nitrogen use efficiency to achieve GHG mitigation targets. The emission intensity indicators derived from this study can be used for regional agricultural land use planning to maintain designated levels of emissions and implement low-emission farms.