Comprehensive review on production and utilization of biochar

The on-farm burning of crop residues and biomass results in numerous environmental issues and affects human beings. Crop residues have considerable energy potential if utilized appropriately. Crop residues can be converted into biochar through thermo-chemical routes; conversion helps in the managing and handling of biomass. Biochar reactors usually operate at temperatures between 400 and 600 degrees C with fixed carbon contents ranging from 60 to 85%. The application of this biochar to soil improves the physiochemical characteristics of soil because biochar is rich in organic carbon content, which makes the soil more fertile and acts as a carbon sequestration agent over the long term. Biochar itself is considered a source nutrient and can alter the soil nutrient pools and availability. Biochar applied up to 10 cm depth of soil may decrease the denitrification potential and lower N2O emission, greatly controlling leaching of mobile nutrients such as potassium, thus improving water use efficiency, nutrient availability and plant growth. Furthermore, it reduces the leaching of nitrogen into the groundwater and increases the water retention and cation-exchange capacity while moderating the soil's acidity, resulting in improved soil fertility. This article discusses different biochar production processes and various feedstocks and characteristics of biochar. The factors affecting biochar production and advantages of the utilization of biochar in soil are also reviewed.