Influence of biochar on the soil water retention characteristics (SWRC): Potential application in geotechnical engineering structures

• Published in: Soil & tillage research Vol. 204; p. 104713
• Main Authors: Hussain, Rojimul, Ravi, K., Garg, Ankit
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2020
• Subjects: agricultural soils; Amendment; Biochar; biomass; carbon sequestration; feedstocks; green roofs; Inter-particle pores; Intra-particle pores; landfills; particle size; pollutants; Pyrolysis; soil fertility; soil water retention; surface area; SWRC; temperature; tillage; vegetation; Inter-particle pores; Pyrolysis; Amendment; SWRC; Biochar; Intra-particle pores
• ISSN: 0167-1987; 1879-3444
• DOI: 10.1016/j.still.2020.104713

•A detailed review of soil water retention characteristics (SWRC) of biochar-amended soil is presented.•Biochar feedstock type, pyrolysis temperature, particle size and aging has a strong influence on the SWRC.•The SWRC of biochar-amended soil also depends on soil type and corresponding compaction condition.•Correlations among SWRC parameters and biochar properties were developed and presented.•Such a study will be quite handy while applying biochar-amended soil in geotechnical and agricultural applications. Biochar is a stable carbon-rich product obtained through pyrolysis of plant and animal-based biomass. Soil is often amended with biochar due to the beneficial features, such as carbon sequestration, improvement of crop growth and yield by enhancing soil fertility, removal of an organic and inorganic pollutant from the soil, and improvement of water retention properties of the soil. Fundamentally, the amendment of soil with biochar alters the soil water retention characteristics (SWRC) of the soil. This is primarily due to the inherent properties of biochar that includes large specific surface area (SSA) by the intra-particle pores, and the functional groups present in biochar surface. SWRC is vital for both agricultural soil and soil in geotechnical or geo-environmental engineering structures due to the presence of vegetation. The effect of biochar on the SWRC of agricultural soil was extensively studied. However, it is rarely studied for soil in geotechnical or geo-environmental engineering structures, such as landfill cover, bioengineered slope, embankment, green roof, etc. Soil in these structures subjects to a distinct condition, in terms of compaction state and design life compared to agricultural soil. Therefore, a comprehensive gathering of information on the effect of biochar on the SWRC and the factors controlling the biochar influence is needed for potential investigation and application of biochar amendment for soil in geotechnical or geo-environmental engineering structures. In this article, the effect of biochar amendment on the SWRC of soil has been reviewed and summarized by considering various factors controlling the influence of biochar on the SWRC. The literature review revealed that the amendment of soil with biochar could improve the SWRC while few occasions not influence the SWRC. Factors, such as feedstock type and pyrolysis temperature, particle size of biochar, soil type, and compaction state have strong bearing on the influence of biochar on the SWRC.