Agro-environmental characterization of biochar issued from crop wastes in the humid forest zone of Cameroon

Purpose Crop wastes are underused organic resources due to low heating value and slow decomposition rates. However, conversion to biochar through pyrolysis could offer agronomic and environmental benefits. The study compared the pyrolysis of biochar from crop wastes, assessed their physicochemical properties for the purposeful use to improve soil fertility, crop productivity and their carbon sequestration potential. Methods Biochar was produced from crop wastes such as cassava residues, corncobs, rice husk, sawdust, coffee husk, and peanut using an Elsa barrel pyrolyser. Standard laboratory procedures were used to analyze pH, CEC, total carbon and nitrogen and exchangeable cations. Results The biochars were high in nutrients containing 4.17–18.15 g kg−1 N, 22.26–42.51 mg kg−1 P, 2.48–4.18 cmol kg−1 K and pH 7.78–10.81 units. It is evident that adding biochar to acidic soil containing 0.79 g kg−1 N, 7.41 mg kg−1 P, 1.42 cmol kg−1 K and pH of 5.68 could increase soil fertility and plant productivity. Carbon dioxide reduction potential ranged from 94.46 to 313.42 CO2 eq kg−1. This implies that the concept and technique of producing biochar could be a valuable way of reducing carbon emissions into the atmosphere thereby mitigating climate change. Conclusion Crop wastes and by-products which constitute a nuisance could be used to produce a very useful by-product, biochar whose quality depends on the substrate from which it is produced. Recycling crop wastes to biochar is strongly recommended to smallholder farmers for use in agriculture to improve fertility and crop productivity due to their high nutrient content and soil fertility attributes.