Biochar improves soil organic carbon sequestration potential in the topsoil and subsoil of a paddy field
Kaiyue Song, Shuo Jiang, Zhiwei Liu, Ying Cai, Wei Liu, Rongjun Bian, Xuhui Zhang, Jufeng Zheng, Lianqing Li
Abstract
We investigated the carbon sequestration potential and underlying mechanisms of a paddy soil amended with biochar for 4 years. By adding maize straw and incubating the soil for 60 days in the laboratory at depths of 0–15 cm, 15–30 cm, and 30–50 cm, we found that biochar reduced soil organic carbon mineralization by 13.5 %, 27.8 % and 16.5 %, respectively. It also decreased cumulative net carbon mineralization and metabolic quotient values induced by fresh substrates at all depths. In addition, biochar and straw increased topsoil hydrolase activity and enhanced the competitiveness of fungi and gram-positive bacteria in the subsoil. • Biochar reduced carbon mineralization at depths of 0‐15 cm, 15–30 cm, and 30–50 cm and inhibited decomposition of fresh substrates in maize straw, showing stronger effects in subsoil compared to topsoil. • Biochar enhanced microbial carbon utilization efficiency at all three soil depths. • In biochar-amended soil enriched with straw, the microbial community in subsoil tends to shift from r -strategists bacteria to K -strategists (fungi and gram-positive) bacteria.