Effect of biochar addition on nutritional status, maturity, and phytotoxicity of cow dung-fortified kitchen waste

In this study, kitchen waste which is otherwise discarded or allowed to putrefy and pose environmental discomfort is co-composted with biochar to assess the effects of the biochar on the composting of kitchen waste as well as the quality of the final compost. To achieve this, biochar was composted with kitchen waste (w/w) in ratios of 10%, 20%, 30%, and 40% to determine its effect on composting process and the final compost product compared to cow dung-fortified kitchen waste as a control. Results indicate that pH and EC were not affected by biochar content during composting; however, biochar content had a profound effect on the attainment of thermophilic temperatures during composting, nitrification and other maturity/stability indexes such as germination index (GI), humification index (HI), degree of polymerization (DP) and HA/FA ratio. In effect, higher biochar content (more than 10% biochar/feedstock ratio) favored faster humification, higher available P and S content.