Linking chemical structure of dissolved organic carbon and microbial community composition with submergence-induced soil organic carbon mineralization

Chao Ma; Xi Chen; Jingzhi Zhang; Yuanpeng Zhu; Yusef Kianpoor Kalkhajeh; Rushan Chai; Xinxin Ye; Hong-Jian Gao; Wenying Chu; Jing-Dong Mao; Michael L Thompson

doi:10.1016/j.scitotenv.2019.07.286

Linking chemical structure of dissolved organic carbon and microbial community composition with submergence-induced soil organic carbon mineralization

Sci Total Environ. 2019 Nov 20:692:930-939. doi: 10.1016/j.scitotenv.2019.07.286. Epub 2019 Jul 19.

Authors

Affiliations

¹ Anhui Province Key Laboratory of Farmland Ecological Conservation and Pollution Prevention, School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China.
² Anhui Province Key Laboratory of Farmland Ecological Conservation and Pollution Prevention, School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China. Electronic address: hjgao@ahau.edu.cn.
³ Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529, USA.
⁴ Agronomy Department, Iowa State University, Ames, IA 50011, USA.

PMID: 31539997
DOI: 10.1016/j.scitotenv.2019.07.286

Abstract

Much research has been devoted to investigating how water-extractable organic carbon (DOC) concentration and microbial activity regulate soil organic carbon (SOC) mineralization when soils are saturated with water. However, the relationships of DOC chemical structure and microbial community composition with SOC mineralization, as well as the relative contributions of microbial decomposers and their substrates on the mineralization rate have rarely been examined. In a laboratory experiment, we incubated two typical cropland soils (an Entisol and a Mollisol) of China for 360 days under submerged and non-submerged conditions, and we evaluated the concentration and chemical structure of soil DOC, soil microbial metabolic potential and community composition by using total C/N analysis, solution-state ¹H NMR, Biolog EcoPlates, and 16S rRNA amplicon sequencing, respectively. The results showed that submergence significantly increased DOC concentration (P < 0.01) and microbial activity (P < 0.001) and changed DOC chemical structure in the Entisol (P < 0.01). In the Mollisol, it significantly increased the rate (P < 0.01) and cumulative extent (P < 0.001) of SOC mineralization and DOC concentration (P < 0.01) as well as altering the composition of the microbial community (P < 0.001). Moreover, the SOC mineralization rate was better explained by microbial community composition (Entisol: SPC = -0.71, P < 0.001; Mollisol: SPC = 0.92, P < 0.001) than by DOC concentration (Entisol: SPC = 0.21, P > 0.05; Mollisol: SPC = 0.30, P < 0.05) or DOC chemical structure (Entisol: SPC = 0.12, P > 0.05; Mollisol: SPC = -0.45, P < 0.001). Our study revealed that the bacterial community composition had a close relationship to the rate of submergence-induced SOC mineralization in both soils, but only DOC concentration and chemical structure were effective predictors of mineralization rate in the low-pH Mollisol.

Keywords: Concentration and chemical structure of soil DOC; Cropland soils; Soil microbial metabolic potential and community composition; Solution-state (1)H NMR; Submergence-induced SOC mineralization.