We synthesized 20 years of research to explain the interrelated processes that determine soil and plant responses to biochar. The properties of biochar and its effects within agricultural ecosystems largely depend on feedstock and pyrolysis conditions. We describe three stages of reactions of biochar in soil: dissolution (1–3 weeks); reactive surface development (1–6 months); and aging (beyond 6 months). As biochar ages, it is incorporated into soil aggregates, protecting the biochar carbon and promoting the stabilization of rhizodeposits and microbial products. Biochar carbon persists in soil for hundreds to thousands of years. By increasing pH, porosity, and water availability, biochars can create favorable conditions for root development and microbial functions. Biochars can catalyze biotic and abiotic reactions, particularly in the rhizosphere, that increase nutrient supply and uptake by plants, reduce phytotoxins, stimulate plant development, and increase resilience to disease and environmental stressors. Meta‐analyses found that, on average, biochars increase P availability by a factor of 4.6; decrease plant tissue concentration of heavy metals by 17%–39%; build soil organic carbon through negative priming by 3.8% (range −21% to +20%); and reduce non‐CO₂ greenhouse gas emissions from soil by 12%–50%. Meta‐analyses show average crop yield increases of 10%–42% with biochar addition, with greatest increases in low‐nutrient P‐sorbing acidic soils (common in the tropics), and in sandy soils in drylands due to increase in nutrient retention and water holding capacity. Studies report a wide range of plant responses to biochars due to the diversity of biochars and contexts in which biochars have been applied. Crop yields increase strongly if site‐specific soil constraints and nutrient and water limitations are mitigated by appropriate biochar formulations. Biochars can be tailored to address site constraints through feedstock selection, by modifying pyrolysis conditions, through pre‐ or post‐production treatments, or co‐application with organic or mineral fertilizers. We demonstrate how, when used wisely, biochar mitigates climate change and supports food security and the circular economy.

In this work, the occurrence of contaminants in drinking water sources was described in relation to their treatment options based on both conventional (e.g., coagulation-flocculation, sedimentation filtration, and chlorination) and advanced treatment techniques (e.g., membrane filtration, ozonation, and biofiltration). However, due to apparent drawbacks of these methods (e.g., formation of disinfection by-products (DBPs)), it is desirable to develop an alternative option for safe drinking water. In this respect, biochar is recognized as an effective candidate to resolve the limitations in treating common pollutants typically occurring in drinking water such as microbial contaminants, inorganic contaminants, heavy metals, volatile organic compounds (VOCs), pharmaceuticals and personal care products (PPCPs), and endocrine disrupting chemicals (EDCs). As biochar can exhibit different types of interactions with adsorbates, its sorption processes can be explained by diverse mechanisms, e.g., π-π electron donor-acceptor interactions, complexation, precipitation, H-bonding, and electrostatic attraction. In light of the attractive features of biochar (e.g., enhanced sorption properties, cost-effectiveness, and environmentally friendly nature), we offer in-depth discussion on biochar-based water treatment technologies for large-scale water purification operation.

Purpose of Review: This paper offers a thorough overview of the processes of nutrient enrichment by biochar and how biochar as a nutrient carrier can effectively improve agricultural productivity. The distributions of nutrients in biochar and the dynamics of nutrients in soil are also reviewed in detail. Recent Findings: The application of biochar improves soil health by changing the soil’s biological and physico-chemical characteristics of the soil, such as its structure, cation exchange capacity and microbial biomass carbon. Additionally, biochar produced from low pyrolysis temperatures can enhance nutrient retention in soils and be utilized as a carbon-based fertilizer. Summary: The maintenance of an adequate amount of organic matter in soil and a dynamic biogeochemical cycle of essential nutrients are key components of sustainable soil management. Biochar is a carbonized biomass derived from various feedstock materials, including wood and crop residues, manures, biosolids and animal carcasses. Biochar has been used for more than two decades as a soil amendment to improve soil physicochemical conditions and mitigate soil contamination. Nutrient-enriched biochar-based fertilizers (NEBBF) can be prepared using various nutrient enrichment procedures and have the potential to increase soil fertility and crop productivity. The application of NEBBF, which is a carbon-based nutrient source, has been shown to enhance microbial activity, thereby increasing the efficiency of nutrient use compared to conventional non-carbon-based synthetic fertilizers. This review identified key research gaps and discussed the importance and necessity of biochar as a nutrient carrier in agriculture.