Assessing Greenhouse Gas Emissions from Integrated Rice-crop Systems in the Dry Zone of Sri Lanka: A Case Study in Ampara District

Abstract

Rice is the staple food in Sri Lanka and requires substantial agronomic inputs to achieve optimal yields necessary to meet the nation’s growing demand. However, paddy cultivation is a major contributor to environmental degradation, accounting for approximately 52% of the agricultural sector’s greenhouse gas (GHG) emissions. This study aimed to quantify the global warming potential (GWP) of a paddy intercropping system in the Ampara district of Sri Lanka. The study was conducted on a 4.825-hectare plot, comprising 4.425 hectares under paddy, 0.2 hectares under turmeric, and 0.2 hectares under cowpea. The total GHG emissions from paddy cultivation were calculated to be 19,136.72 kg CO₂ eq/ha annually, with nitrous oxide (N₂O) emissions from soil leaching being identified as the primary source. Paddy, turmeric, and cowpea contributed 88.43, 10.46, and 1.11%, respectively, to the total GHG emissions from the intercropping system. It was further observed that incorporating cowpea in 10% of the cultivated area could reduce total GHG emissions from paddy by 6.76%. Additionally, the adoption of sustainable practices, including the application of composted rice straw, biochar, and deep placement of urea fertilizers, presents significant potential for mitigating the GWP of paddy-based cropping systems. These results underscore the necessity of integrating climate-smart agricultural techniques to reduce the carbon footprint of rice production while maintaining sustainable yield levels critical for national food security.