Impact of Biochar on Soil Fertility and Behaviour of Xenobiotics in Soil

Abstract

The different xenobiotic compounds, such as insecticides, fungicides, herbicides, chlorinated derivatives and polycyclic aromatic hydrocarbons (PAHs), which are widely used in agricultural activities for increased crop production and other human benefits, can enter the soil and water environments and cause significant toxic impacts on the soil health, microorganisms, ecosystem, human health and environmental quality. The application of biochar to soil can improve soil health and fertility, soil organic matter, nutrient content, pH and soil water retention and aggregation, but reduce soil greenhouse gas emissions, soil bulk density, erosion potential and leaching of pesticides and nutrients to surface and groundwater and mitigate climate change impacts. The biochar has high potential to remediate the soils contaminated by xenobiotic compounds reducing their mobility and bioavailability in soil. This book chapter has reviewed (1) biochar production properties and their effects on soil fertility, physical, chemical and biological properties; (2) the fate and behaviour of xenobiotics in soil, illustrating their interaction with soil constituents and uptake by plants; and (3) the remediation techniques to reduce mobility and bioavailability of the xenobiotic compounds through biochar application to soil. Depending on the type, amount of biochar applied and the physicochemical properties of the biochar itself, it may change the soil properties as well as impact the use, rates, efficacious properties and fates of xenobiotic compounds used in agronomic management. The effects of biochar on the fate and mobility of xenobiotic compounds in soil ecosystems depend on the soil types and properties. Since biochars contain colloidal-sized particles that move through soil pore water flows, colloid-facilitated transport could actually enhance mobility and leaching of xenobiotic compounds in the presence of biochar. Increased sorption to soils and recalcitrance of pesticides leading to longer residence times in the environment is desirable if bioactivity is still acceptable, and it controls the target pest. However, longer residence time may also create some environmental problems, such as greater leaching potential or carry-over problems into the following season.