Soil organic and inorganic carbon sequestration by consecutive biochar application: Results from a decade field experiment

Abstract

Biochar addition can expand soil organic carbon (SOC) stock and has potential ability in mitigating climate change. Also, some incubation experiments have shown that biochar can increase soil inorganic carbon (SIC) contents. However, there is no direct evidence for this from the field experiment. In order to make up the sparseness of available data resulting from the long‐term effect of biochar amendment on soil carbon fractions, here we detected the contents and stocks of the bulk SIC and SOC fractions based on a 10‐year field experiment of consecutive biochar application in Shandong Province, China. There are three biochar treatments as no‐biochar (control), and biochar application at 4.5 Mg ha−1 year−1 (B4.5) and 9.0 Mg ha−1 year−1 (B9.0), respectively. The results showed that biochar application significantly enhanced SIC content (3.2%–24.3%), >53 μm particulate organic carbon content (POC, 38.2%–166.2%) and total soil organic carbon content (15.8%–82.2%), compared with the no‐biochar control. However, <53 μm silt–clay‐associated organic carbon (SCOC) content was significantly decreased (14%–27%) under the B9.0 treatment. Our study provides the direct field evidence that SIC contributed to carbon sequestration after the biochar application, and indicates that the applied biochar was allocated mainly in POC fraction. Further, the decreased SCOC and increased microbial biomass carbon contents observed in field suggest that the biochar application might exert a positive priming effect on native soil organic carbon.

Biochar–compost mixture and cover crop effects on soil carbon and nitrogen dynamics, yield, and fruit quality in an irrigated vineyard

“…wheat, corn and ryegrass) reported a significant increase in soil C as a result of biochar application (Shi et al 2021;Weng et al 2017). Shi et al (2021) observed 16 to 82% increase in soil organic C content by 10 years annual application of 4.5 and 9.0 Mg ha -1 corn cobs biochar in winter wheat-corn rotation in a silt loam soil in Shandong Province, China. In their study biochar C was mainly allocated to particulate organic C fraction (38-166%).…”

Sustainable soil management and climate change mitigation

“…A field experiment conducted over a period of a decade found that biochar application significantly increased both inorganic and organic carbon contents in soil, with the most significant increase in the particulate organic carbon content. However, biochar application was also found to have reduced silt and clay associated organic carbon, likely due to biochar's priming effect on natural soil carbon (Shi et al., 2021). The application of soil amendment may also enhance aggregate formation and improve the stability of soil organic matter, for example a structural equation model revealed that manure fertilization stimulates microbial growth, which renders polysaccharide‐C and aliphatic‐C in intra‐particulate organic matter to facilitate macro‐aggregate formation (Wen et al., 2021).…”

Sustainable futures over the next decade are rooted in soil science

“…In addition, there is vast potential for the sequestration of soil inorganic carbon as secondary carbonates and bi‐carbonates (Lal, 2019). For instance, a recent study showed that although biochar addition can expand soil organic carbon stocks, it can also increase the dissolved inorganic carbon content in soils (Shi et al, 2020).…”