A Critical-Systematic Review of the Interactions of Biochar with Soils and the Observable Outcomes

Abstract

Biochar research has experienced a significant increase in the recent two decades. It is growing quickly, with hundreds of reviews, including meta-analyses, that have been published reporting diverse effects of biochar on soil properties and plant performance. However, an in-depth synthesis of biochar–soil interactions at the molecular level is not available. For instance, in many meta-analyses, the effects of biochar on soil properties and functions were summarized without focusing on the specificity of the biochar and soil properties. When applied to soils, biochar interacts with different soil components including minerals, organic matter, gases, liquids, and nutrients, while it also changes soil microbial community structure and their occurrence. These different interactions modify soil physicochemical properties with consequences for dynamic changes in nutrient availability and, thus, plant performance. This review systematically analyzed biochar effects on soil properties and functions: (a) soil physical properties; (b) chemical properties; (c) biological properties; and (d) functions (plant performance, nutrient cycling, etc.). Our synthesis revealed that the surface properties of biochar (specific surface area and charge) and its associated nutrient content determine its role in the soil. At the same time, the extent of changes depends on soil properties, suggesting that both biochar and soil properties need to be considered for harvesting benefits of biochar application. Altogether, we believe our synthesis will provide a guide for researchers and practitioners for future research as well as large-scale field applications.

WITHDRAWN: Optimization and characterization of biochar obtained from weedy biomass of Calotropis gigantea by vacuum pyrolysis

“…Thus, from FTIR results it is interpreted that due to pyrolysis at 450°C temperature thermal degradation of hemicellulose and cellulose have occurred whereas some aromatics functional group related to lignin remain in biochar. This characteristics enables biochar as potential source for soil improvement (Nkoh et al 2021, Kalina et al 2022. Further application of Calotropis biochar could contribute, by cation exchange capacity/complexation/precipitation, to the treatment of soil and waste water pollutants due to the presence of oxygen based functional group and aromatic structure.…”

Impact of Pyrolyzed and Unpyrolyzed Animal Manures on Soil Properties, Carbon Sequestration, and Clover Productivity in Andisol

“…While Andosols exhibit a significant pH-buffering ability [47], this research found that biochars (PLBC, DBC) and PL elevated the soil's pH level (refer to Table 2). Biochars are basic substances, and their alkalinity is influenced by the ash content in their raw materials, as well as by their organic and inorganic bases, carbonates, and functional groups [48]. In addition, unstable feedstocks such as manures have a high potential to provide ash content due to their richer concentrations of volatile matter than wood-based biochars [49].…”

The Importance of the Targeted Design of Biochar Physicochemical Properties in Microbial Inoculation for Improved Agricultural Productivity—A Review

“…Functional groups located on biochar surfaces can retain and provide nutrients for the growth of microorganisms in the soil [146,171]. Biochar is dominated by negatively charged functional groups; therefore, it mostly affects cation retention [172]. However, due to the pH-dependent nature of the surface, it can also contribute to a smaller extent to an anion adsorption [173,174].…”