Impact of Biochar on Soil Physical and Chemical Properties

Biochar, a carbon-rich residue produced by biomass pyrolysis, has sparked global attention as a soil amendment capable of improving soil fertility, increasing carbon sequestration, and contributing to climate mitigation efforts.  Numerous studies have shown that biochar may influence soil physical characteristics (bulk density, porosity, water-holding capacity, aggregation) and chemical properties (pH, cation exchange capacity, nutrient retention, and contaminant dynamics). However, reactions are heavily context-dependent: feedstock, pyrolysis temperature, application rate, and baseline soil properties all influence results.  This article summarizes current knowledge of how biochar affects soil physical and chemical properties, describes the mechanisms underlying those changes, and provides practical considerations for farmers and land managers looking to reap biochar's advantages while avoiding any negatives.