期刊
SOIL BIOLOGY & BIOCHEMISTRY
卷 50, 期 -, 页码 12-21出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.soilbio.2012.02.033
关键词
Dissolved organic matter; Organic matter solubilization; Microbial activity; Abiotic factors; Abiotic solubilization
类别
资金
- University of Canterbury
- New Zealand Postgraduate Study Abroad scholarships
- J. G. Boswell Endowed Chair in Soil Science
Dissolved organic matter (DOM) is a small but reactive pool of the soil organic matter (SOM) that contributes to soil dynamics including the intermediary pool spanning labile to resistant SOM fractions. The solubilization of SOM (DOM production) is commonly attributed to both microbially driven and physico-chemically mediated processes, yet the extent to which these processes control DOM production is highly debated. We conducted a series of experiments using C-13-ryegrass residue or its extract (C-13-ryegrass-DOM) separately under sterile and non-sterile conditions to demonstrate the importance of DOM production from microbial and physico-chemical processes. Soils with similar properties but differing in parent material were used to test the influence of mineralogy on DOM production. To test the role of the source of C for DOM production, one set of soils was leached frequently with C-13-ryegrass-DOM and in the other set of soils C-13-ryegrass residue was incorporated at the beginning of the experiment into the soil and soils were leached frequently with 0.01 mol L-1 CaCl2 solution. Leaching events for both treatments occurred at 12-d intervals over a 90-day period. The amount of dissolved organic C and N (DOC and DON) leached from residue-amended soils were consistently more than 3 times higher in sterile than non-sterile soils, decreasing with the time. Despite changes in the concentration of DOC and DON and the production of CO2, the proportion of DOC derived from the C-13-ryegrass residue was largely constant during the experiment (regardless of microbial activity), with the majority (about 70%) of the DOM originating from native SOM. In C-13-residue-DOM treatments, after successive leaching events and regardless of the sterility conditions i) the native SOM consistently supplied at least 10% of the total leached DOM, and ii) the contribution of native SOM to DOM was 2-2.9 times greater in C-13-residue-DOM amended soils than control soils, suggesting the role of desorption and exchange reactions in DOM production in presence of fresh DOM input. The contribution of the native SOM to DOM resulted in higher aromaticity and humification index. Our results suggest that physico-chemical processes (e.g. exchange or dissolution reactions) can primarily control DOM production. However, microbial activity affects SOM solubilization indirectly through DOM turnover. (C) 2012 Elsevier Ltd. All rights reserved.
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