biochars

Biochar is a stable form of carbon produced when biomass is heated in a low-oxygen environment, a process known as pyrolysis. Common feedstocks include crop residues, wood waste, manure, and other organic materials. The resulting material varies with production temperature, heating rate, and residence time, which influence its stability, porosity, nutrient content, and pH. Biochar is characterized by its aromatic carbon structure, high surface area, and persistence in soil for years to centuries.

In soil, biochar can improve physical properties such as porosity and water-holding capacity, and chemical properties including cation exchange capacity and pH, depending on feedstock and ash content. It can adsorb nutrients and contaminants, reduce nutrient leaching, and provide habitat for soil microbes. The stability of biochar means carbon is sequestered in soils for long periods, contributing to climate change mitigation in some life cycle assessments.

Applications include soil amendment for agriculture and forestry, land restoration, and integration into composting or manure management. It is also studied for remediation of polluted soils and water by adsorption of organic pollutants and heavy metals.

Environmental aspects: the environmental performance depends on feedstock, production energy, and management. Potential drawbacks include emissions during production, contamination from heavy metals or persistent pesticides in feedstocks, and possible nutrient immobilization or pH shifts in soils. Standards and best practices continue to develop as researchers assess long-term effects and economic viability.