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 °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 N 2 O 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.

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The burning of crop residue results in numerous environmental issues and also affects human beings. Crop residue has the potential to produce considerable energy and can be converted into biochar via thermochemical routes; this conversion helps in the management and handling of biomass. This study deals with the development of a system for the continuous production of biochar by carbonization of groundnut shells at different temperatures. The developed system is capable of converting different kinds of crop residue into biochar. The carbonization chamber was heated using an industrial burner, and its thermal performance was elevated at 400, 450, and 500°C using groundnut shell as feedstock, and the amount of time the feedstock resided in the burner was limited to 4 min. The mass yields and heating value of the produced biochar were found to be highest at 400°C. Therefore, the crop residue converted into biochar and the chemical properties were assessed for this temperature. Biochar conversion efficiency was recorded at about 30%. The oxygen-to-carbon (O:C) and hydrogen-to-carbon (H:C) ratios were found to be 0.08 and 0.40 respectively. The energy required to produce 1 kg of biochar ranged from 3.70 to 4.64 MJ. The benefit-cost ratio and a payback period of the developed system were calculated to be about 1.94 and 11 months, respectively. The internal rate of return was estimated at about 121%. In the present study, the impact of carbonization upon the composition of lignocelluloses and its thermal behavior was also assessed with the help of a thermogravimetric analyzer (TGA).

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