Contribution of Composting and Surface Decomposition of Farm Waste to the Mitigation of CO2 and CH4 from Selected Farm Wastes in Masaka and Lyantonde Districts
Agriculture in Uganda is the leading sector, employing over 85% of the entire population, with 68% of farmers struggling as smallholder farmers. Thus, agriculture is dominated by smallholder farmers. Available reports emphasize the contribution of the agricultural sector to greenhouse gas emissions (GHG), such as carbon dioxide (CO2) and methane (CH4). During the course of farming, smallholder farmers make many attempts to either benefit from the farm wastes generated or to get rid of them directly or indirectly. Thus, we realize some go for composting, which is intentional, while others opt for surface decomposition, which is seen as the default approach. Whatever option of waste management is chosen, there is efficacy for the method. The type of system waste component and waste management practice greatly contribute to GHG emissions, such as CO2 and CH4. The efficacy of each method varies considerably in terms of mitigating GHG emissions. This study considered farm wastes (bean trash, maize trash, banana trash, cattle slurry, goat slurry, and pig slurry) commonly produced by smallholder farmers in two farming systems of Masaka and Lyantonde Districts to: estimate the relative carbon dioxide and methane emissions of each selected farm waste component in different farming systems (arable and mixed, represented by Masaka and Lyantonde Districts, respectively), and estimate the relative carbon dioxide and methane emissions of selected aggregated farm waste. Using a gas analyzer F-950 (three-gas analyzer), we determined carbon dioxide and oxygen from airtight containers in which individual farm wastes/aggregated farm wastes were contained. Basing our calculations on the gas laws, we used a formula
to compute and obtain corresponding methane values. Results revealed that composting beans from the arable farming system captured the highest volume of 784.3 ppm of CO2 and 978.7 ppm of CH4 at 3000 cm？1. In the mixed farming system, pig slurry produced the highest volume of CH4 (556 ppm), while maize produced more CO2 volumes under composting (602 ppm). The mixed
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