Soil acidification and the liming potential of biochar

Soil acidification in managed ecosystems such as agricultural lands principally result from increased releasing of protons (H+) from the transformation reactions of carbon (C), nitrogen (N) and sulphur (S) containing compounds. The incorporation of liming materials can neutralize the protons released, hence reducing soil acidity and its adverse impacts to soil environment, food security, and human health. Biochar derived from organic residues are becoming a source of carbon input to soil and provide multifunctional values. Biochar can be alkaline in nature with the level of alkalinity dependent upon the feedstock and processing conditions. This review covers the fundamental aspects of soil acidification and of the use of biochar to address constraints related to acidic soil. Biochar are increasingly considered as an effective soil amendment for improving soil acidity owing to its liming potential, thereby enhancing soil fertility and productivity in acid soils. The ameliorant effect on acid soils is mainly because of the dissolution of carbonates, (hydro)-oxides of the ash fraction of biochar and potential use by microorganisms.