FERTILIZER QUALITY AND CARBON SEQUESTRATION POTENTIAL OF COMPOST GENERATED FROM CLEAN-DEVELOPMENT MECHANISM MUNICIPAL ORGANIC SOLID WASTE COMPOSTING PLANTS IN UGANDA

Municipal Organic Solid Waste (MOSW) management in developing countries remains a major urban challenge, yet is valuable resource in agriculture. Cities generate large quantities of causing environmental pollution and greenhouse gas (GHG) emission. In Uganda, municipalities were supported under Clean Development Mechanism (CDM) to compost MOSW. A study was conducted in nine municipal waste management plants to estimate GHS mitigation and evaluate the quality of compost from the windrow technology. Composting reduced 90% of CH4 emission compared to landfilling and GHG estimated at 24.6 Mg year-1 and the compost generated added 3886 and 7.8 Mg year-1 of organic carbon and stable carbon into the soil, respectively. The sites produced compost with a fertilizer potential of 9886, 20247 and 102892 ha of N, P and K, respectively. The quality of compost significantly varied across the sites (p< 0.001) and months (p< 0.001) attribute to agroecological zones and agricultural seasons. The concentrations of total nitrogen ranged between 7.06 – 15.44 g kg-1, organic carbon (81.7 – 160.6 g kg-1) with C: N ratio < 12 indicating matured compost. The concentrations of phosphorus ranged between 3.03 to 3.37 g kg-1 while potassium was 10.30 to 51.42 g kg-1, calcium 12.42 to 55.56 g kg-1 and magnesium 1.3 to 5.48 g kg-1 in compost. The maximum detected Pb concentration was 51.1 mg kg-1 indicating low risk of Pb accumulation in soil following application of compost. It was concluded that composting reduced GHG emission and recovered fertilizer resources with low-risk heavy metal contaminants.