Effect of Biochar on Soil Properties – A Review

Biochar is produced by carbonizing organic matter under high temperatures in a little to no oxygen environment. There are seven key factors to evaluate biochar, including pH, volatile organic compound content, water holding capacity, ash content, density, pore volume, and surface volume. The choice of raw materials affects the end biochar product, changing its chemical component level, hardness, density, and porosity. Biochar has a notable influence on soil properties. This review summarizes biochar’s effect on soil physical properties, hydraulic properties, microbial biomass, and soil remediation. Biochar decreases the bulk density by interacting with soil particles, enhancing porosity. Thus, soil forms a good structure and serves as an excellent medium for the transport and uptake of water and nutrients. Available water content (AWC), saturation water content (SWC), water holding capacity (WHC), and permanent wilting point (WP) significantly increase with biochar application. Additionally, biochar-amended soils have greater hydraulic conductivity values. Furthermore, biochar application alters the abundance of soil microorganisms by modifying the soil. In certain stressed environments, biochar promotes the colonization of mycorrhizal fungi, encouraging root growth. Biochar can effectively immobilize heavy metals and organic pollutants in the soil through various sorption mechanisms. Despite its advantageous nature, biochar can change nutrient availability and soil nutrient ratios, which could adversely affect plant growth. Altogether, these recent studies suggest that biochar has a huge capacity for boosting soil health and reducing environmental pollution.