Effects of long-term fertilization on calcium-associated soil organic carbon: Implications for C sequestration in agricultural soils

Dan Wan; Mingkai Ma; Na Peng; Xuesong Luo; Wenli Chen; Peng Cai; Lihui Wu; Haibin Pan; Jiubin Chen; Guanghui Yu; Qiaoyun Huang

doi:10.1016/j.scitotenv.2021.145037

Effects of long-term fertilization on calcium-associated soil organic carbon: Implications for C sequestration in agricultural soils

Sci Total Environ. 2021 Jun 10:772:145037. doi: 10.1016/j.scitotenv.2021.145037. Epub 2021 Feb 2.

Authors

Dan Wan¹, Mingkai Ma², Na Peng², Xuesong Luo², Wenli Chen³, Peng Cai², Lihui Wu⁴, Haibin Pan⁴, Jiubin Chen⁵, Guanghui Yu⁵, Qiaoyun Huang⁶

Affiliations

¹ State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China; Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China.
² State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China.
³ State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China.
⁴ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China.
⁵ Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China.
⁶ State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China. Electronic address: qyhuang@mail.hzau.edu.cn.

PMID: 33578172
DOI: 10.1016/j.scitotenv.2021.145037

Abstract

Although the contribution of calcium ion (Ca²⁺) to stabilizing organic carbon (OC) in soils has been known for years, we still have a limited understanding of the quantity and molecular composition of Ca²⁺ bound SOC (Ca-OC) evolution in response to long-term fertilization. Here we report the role of Ca²⁺ in the accumulation of OC in the topsoil (0-20 cm) from two long-term (25-37 years) fertilization experiment sites. Approximately 4.54-19.27% and 9.00-25.15% of SOC was bound with Ca²⁺ in the Ferric Acrisol and Fluvic Cambisol, respectively. The application of NPK mineral fertilizers (NPK) decreased (p < 0.05) the Ca-OC stocks from 3.40 t ha^-1 to 0.96 t ha^-1 and from 2.03 t ha^-1 to 1.17 t ha^-1 in the Ferric Acrisol and Fluvic Cambisol, respectively. Swine manure (M) addition did not change (p > 0.05) the Ca-OC stock in Ferric Acrisol, but enhanced (p < 0.05) that from 2.03 t ha^-1 to 9.75 t ha^-1 in Fluvic Cambisol. Fourier transform infrared and carbon (1s)-near X-ray absorption spectroscopies showed that Ca²⁺ was mainly bound with aromatic carbon and carboxylic carbon. Long-term M fertilization facilitated the binding of Ca²⁺ with O-alkyl C, suggesting an increment of Ca-linked polysaccharide. Calcium ion was preferentially associated with ¹³C enriched organic matter (OM). Mineral fertilization promoted the ¹³C-enriched organic compounds in the Ca-OC, while organic fertilization facilitated the binding of ¹³C-depleted organic C with Ca²⁺. This study suggests that Ca-OC may be a potentially vital and stable OC pool in arable soils, and provides direct evidence for the preferential association of OC with Ca²⁺ in edaphic environments.

Keywords: Chemical protection; Organo-mineral interactions; Soil organic carbon stabilization; Stable carbon isotopic composition; Wheat-maize rotation.