Effects of adding Rice Husk Biochar on GHG Emission and Compost Quality during Cow Manure Composting

Abstract

Agriculture is a major anthropogenic source of Green House Gases (GHG) and contributes 24% of total GHG emitted (IPCC, 2014). Livestock sector forms a significant part of agriculture and is responsible for major GHG emission. According to FAO, 2016, livestock manure contributes 23% to total GHG emitted in agricultural sector. N₂O, CO₂ and CH₄ are important GHG emitted during management of livestock manure. Against the background of global warming, there is increased motivation in reducing GHG emission. Therefore, this study deals to see the effects in N₂O, CO₂ and CH4 emission by adding 5%, 10% and 15% of rice husk biochar during cow manure composting. In addition, degradation rate and C/N ratio of manure samples were analyzed for determining the final compost quality. Subsequently, a composting experiment was conducted using rice husk biochar and gases emitted were measured periodically with static gas chamber method. The experimental results indicated that biochar was effective in reducing N₂O and CO₂ emissions. The cumulative emission of N₂O was reduced by 40% in 5% treatment, 46% in 10% treatment and 60% in 15% treatment. Similarly, there was decrease of CO₂ by 69% in 5% treatment, 68% in 10% treatment and 48% in 15% treatment. Biochar’s well developed pore structure and adsorption capacity reduced the gas emission. Furthermore, addition of biochar enhanced degradation rate and better C/N ratio. Biochar addition provided necessary nutrients and habitat, facilitating growth of various microorganisms. The results of CH₄ emission did not show any significant difference between the treatments. The obtained results indicate that rice husk biochar addition is beneficial in reducing GHG emission and improving compost quality with faster degradation and better C/N ratio.