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Iron oxides selectively stabilize plant‐derived polysaccharides and aliphatic compounds in agricultural soils
Author(s) -
Wan Dan,
Ye Tinghong,
Lu Yong,
Chen Wenli,
Cai Peng,
Huang Qiaoyun
Publication year - 2019
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/ejss.12827
Subject(s) - soil water , arable land , chemistry , environmental chemistry , soil carbon , adsorption , total organic carbon , carbon fibers , soil science , agriculture , geology , organic chemistry , materials science , ecology , composite number , composite material , biology
A strong link exists between iron oxides and soil organic carbon (SOC). However, the role of iron oxides in the preservation of SOC in agricultural soil remains poorly understood. In this study, we comprehensively examined the concentration, molecular composition and biological sources of iron oxide‐bound organic carbon (Fe‐bound OC) in arable soils collected from 12 sites in central and east China. The results indicated that 6.2–31.2% of the SOC was bound to iron oxides in agricultural soil and that the binding mechanisms varied from adsorption in most soils to coprecipitation in those with a large content of organic carbon. The distribution of Fe‐bound OC showed no clear variation in relation to site, but Fe‐bound OC reached a peak in soils with an annual mean temperature of 16.4°C. Correlation analysis demonstrated that TOC might be the main determinant for the amount of Fe‐bound OC and that the binding mechanism is influenced by both TOC and the active Fe ratio. Comprehensive studies of C/N, 13 C isotope and synchrotron radiation‐based Fourier transform infrared (SR‐FTIR) spectroscopy showed that iron oxides selectively protected plant‐derived aliphatic compounds and polysaccharides in agricultural soil. This study revealed the quantitative characterization, biological sources and molecular composition of Fe‐bound OC in arable soils, which provides useful information for evaluating and managing the global C cycle under the framework of climate change.