Biochars

Organic residues rich in carbon can be pyrolyzed to produce biochar, a stable form of charcoal with potential for carbon sequestration. Biochar has proven beneficial in tropical soils, enhancing pH, nutrient retention, and plant growth. While its mechanisms are not fully understood, biochar's high porosity, surface area, and chemically reactive groups, such as COOH and OH, suggest it can adsorb toxic substances like Al, Mn, As, and Cd. This makes biochar especially promising for highly weathered, acidic, or low-organic matter soils. Quality factors include feedstock type and production method, particularly volatile matter (VM) content, which should be low to avoid nutrient immobilization. High-quality biochar can be produced on-farm with simple equipment. Recommended application involves soil incorporation of screened biochar into the root zone, with reported rates ranging from 18 to 112 metric tons/ha (8 to 50 tons/acre).

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