Biochar-plant interactions enhance nonbiochar carbon sequestration in a rice paddy soil
Zhiwei Liu, Wei Zhang, Ruiling Ma, Shixian Li, Kaiyue Song, Jufeng Zheng, Yan Wang, Rongjun Bian, Xuhui Zhang, Genxing Pan
Abstract
Abstract Soil amendment with biochar is being promoted as a promising strategy for carbon (C) stabilization and accrual, which are key to climate change mitigation. However, it remains elusive on how biochar addition influences nonbiochar C in soils and its mechanisms, especially in the presence of plants. Here we conducted a 365-day soil microcosm experiment with and without adding 13 C-labeled biochar into topsoil to quantify changes in nonbiochar C in the topsoil and subsoil in the presence or absence of rice plants and to determine the mechanisms by which biochar controls nonbiochar C accrual in the soil profile. The nonbiochar C content of topsoil was not affected by biochar addition in the absence of rice plants, but was significantly increased by 4.5% in the presence of rice plants, which could result from increases in the soil macroaggregate fraction, iron (Fe)-bound nonbiochar organic C content, and fungal biomass collectively. However, biochar amendment had no effect on the content of nonbiochar organic C in the subsoil. Overall, biochar-plant interactions drive more nonbiochar C sequestration in the topsoil, and the changes of nonbiochar C in planted soils following biochar addition should be quantified to better assess the soil C sequestration potential in agricultural lands.