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Three sources of CO 2 efflux from soil partitioned by 13 C natural abundance in an incubation study
Author(s) -
Kuzyakov Yakov,
Bol Roland
Publication year - 2005
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1938
Subject(s) - chemistry , decomposition , slurry , efflux , sugar , incubation , environmental chemistry , tracer , organic matter , dissolved organic carbon , abundance (ecology) , environmental science , ecology , food science , environmental engineering , biochemistry , organic chemistry , biology , physics , nuclear physics
Abstract This study describes a novel approach to separate three soil carbon (C) sources by one tracer method (here 13 C natural abundance). The approach is based on the combination of C 3 and C 4 sources in different treatments, identical decomposition of C 3 and C 4 substances in soil, and subsequent calculation of their contribution to the total CO 2 efflux. We used the temporal dynamics of the CO 2 efflux from a C 3 grassland soil amended with added C 3 or C 4 slurry and/or C 3 or C 4 sugar to estimate contributions of three separate C sources: native soil organic matter (SOM), slurry and sugar, to CO 2 efflux. Soil with slurry and/or sugar was incubated under controlled conditions, and concentration and δ 13 C values of evolved CO 2 were measured over a 2‐week period. The main assumption needed for separation of three C sources in CO 2 efflux, i.e. identical decomposition of applied C 3 and C 4 sugars in soil, was investigated and proven. The relative contribution to the CO 2 efflux increased, but its duration decreased with an increased microbial availability of the C source, i.e. sugar > slurry > SOM. The microorganisms used the C sources according to their availability. The contribution of sugar to the CO 2 efflux was finished after 2–4 days. Separation of three CO 2 sources and comparison of CO 2 from different treatments tracing the changes of SOM and slurry decomposition induced by addition of sugar were investigated. During the sugar decomposition (the first 2–4 days), the SOM decomposition strongly decreased. At the same time the contribution of slurry‐C to CO 2 increased. The shortcomings and limitations as well as possible future applications of the suggested method including FACE (Free Air Carbon dioxide Enrichments) and continuous labelling experiments are discussed. Copyright © 2005 John Wiley & Sons, Ltd.