Dr Xinliang Dong1,2, Dr Guitong Li2, Prof Bhupinderpal Singh3
1The Center For Agricultural Resources Research, Institute Of Genetics And Developmental Biology, CAS, Shijiazhuang, China, 2China Agriculture University, Beijing, China, 3University of New England, Armidale, Australia
An understanding of the influence of biochar on soil organic carbon (SOC) formed from different carbon (C) sources, other than biochar, at field scale is required to accurately assess and predict the C sequestration potential following application of biochar. For this study, we set up a field experiment in 2009, including four treatments (i.e. B0, B30, B60, and B90, where the biochar application rates were 0, 30, 60, and 90 t ha-1, respectively). We then assessed the impact of biochar on native SOC derived from different plants (C3 and C4) and different SOC fractions, and biochar effect on SIC compositions. After five years, the content of native SOC derived from crop residues increased by 81% (from 4.32 to 7.84 g kg-1) in the B0 treatment, while the increases of native SOC were relatively lower in the B30 (61%), B60 (43%), and B90 (26%) treatments. Thus biochar decreased the content of native SOC compared to the B0. Additionally, biochar decreased “labile pool I” (first-step, weak acid hydrolysable) of native SOC by 11.2–47.7%, compared to the B0, but did not influence “labile pool II” (second-step, strong acid hydolysable) and “recalcitrant pool” (acid non-hydolysable). Using the natural abundance 13C, our results showed that 62–74% of the native SOC was derived from wheat across all the treatments. Biochar application decreased the contribution of wheat-derived C to native SOC by 14.7, 29.0, and 41.5% in the B30, B60, and B90 treatments, respectively, while the content of maize-derived native SOC did not change, relative to the B0. In addition, as biochar application rate increased, δ13C of native soil inorganic C (SIC) decreased, which indicated that pedogenic inorganic C was formed. Biochar application rates were positively related to the pedogenic inorganic C content; however, it did not influence the lithogenic inorganic C content. In summary, the results showed that the long-term (five years) biochar application can improve SIC content, while decreasing native SOC content.
Xinliang Dong studied soil science at the China Agriculture University, where he earned his PhD in 2017. Dr. Dong’s research focuses on the dynamics of soil organic matter derived from different plant sources, and biochar effect on soil organic carbon fractionations.