Impact of biochar amendment in agricultural soils on the sorption, desorption, and degradation of pesticides: A review

Highlights: • Dominant biochar properties affecting pesticide sorption-desorption were reviewed. • Biochar effect on pesticide sorption-desorption in the soil was evaluated. • Aging process usually causes lower sorption capacity of biochar. • Modified biochar provides higher sorption efficiency for pesticides. • How biochar affects the biodegradation of pesticides in soils is inconclusive. Extensive and inefficient use of pesticides over the last several decades resulted in serious soil and water contamination by imposing severe toxic effects on living organisms. Soil remediation using environment-friendly amendments to counteract the presence of pesticides in soil seems to be one suitable approach to solve this problem. Biochar has emerged as a promising material for adsorbing and thus decreasing the bioavailability of pesticides in polluted soils, due to its high porosity, surface area, pH, abundant functional groups, and highly aromatic structure, mainly depending on the feedstock and pyrolysis temperature. However, biochar effects and mechanisms on the sorption and desorption of pesticides in the soil are poorly understood. Either high or low pyrolysis temperature has both positive and negative effects on sorption of pesticides in soil, one by larger surface area and the other by a large number of functional groups. Therefore, a clear understanding of these effects and mechanisms are necessary to engineer biochar production with desirable properties. This review critically evaluates the role of biochar in sorption, desorption, and degradation of pesticides in the soil, along with dominant properties of biochar including porosity and surface area, pH, surface functional groups, carbon content and aromatic structure, and mineralogical composition. Moreover, an insight into future research directions has been provided by evaluating the bioavailability of pesticide residues in the soil, effect of other contaminants on pesticide removal by biochar in soils, effect of pesticide properties on its behavior in biochar-amended soils, combined effect of biochar and soil microorganisms on pesticide degradation, and large-scale application of biochar in agricultural soils for multifunction.