Publication Title : Long-Term Aging of Biochar: A Molecular Understanding With Agricultural and Environmental Implications
Publicationed By : Dr. Shamim Mia
Publication Publication Date : 2016-12-17 00:00:00
Publication Online Link : https://www.sciencedirect.com/science/article/pii/S0065211316301079
Publication Description :
Biochar has unveiled a new avenue for carbon (C) sequestration and has shown the potential to increase agricultural productivity. Although there is still debate about the mineralization rate of biochar and its role in sustaining soil fertility after fresh biochar amendment, oxidized or aged biochar has shown strong positive effects on crop productivity. Aging of biochar changes its physiochemical properties, while a range of biochar-derived organic materials (BDOMs) can be formed. These changes have significant consequences for the bioavailability and transport of nutrients and contaminants. In this review, we provide an overview of biochar aging, focusing on its change in structure, surface chemical properties, and the interactions of biochar and BDOMs with nutrients and contaminants in the soil. Synthesis of spectroscopic data from nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and near edge X-ray fine structure (NEXAFS) showed that with progressive aging, either artificially or naturally, biochar undergoes structural and chemical changes leading to progressive formation of surface functional groups such as carboxyl, phenolic, and carbonyl groups. As a result, the O:C ratio, negative surface charge, and cation exchange capacity increase with increased level of aging. The surface oxidized biochar and BDOMs may interact with soil minerals, nutrients, and contaminants resulting in increased mineral-stabilized organic matter, cation retention, anion bioavailability, and reduced organic contaminants’ sorption. Therefore, application of aged biochar could potentially increase agricultural productivity with increased capacities to retain nutrients while serving the role of C sequestration.