Microbial assimilation of plant-derived carbon in soil traced by isotope analysis |
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Authors: | Oliver Pelz Wolf-Rainer Abraham Matthias Saurer Rolf Siegwolf Josef Zeyer |
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Affiliation: | (1) Swiss Federal Institute of Technology (ETH), Zurich, Institute of Terrestrial Ecology, Soil Biology, Grabenstrasse 3, 8952 Schlieren, Zurich, Switzerland;(2) Division of Microbiology, German National Research Centre for Biotechnology (GBF), Mascheroder Weg 1, 38124 Brunswick, Germany;(3) Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland;(4) Present address: Product Safety Department, BASF Aktiengesellschaft, GUP/CA-Z470, 67056 Ludwigshafen, Germany |
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Abstract: | The flow of new and native plant-derived C in the rhizosphere of an agricultural field during one growing season was tracked, the ratios in different soil C pools were quantified, and the residence times (s) were estimated. For this the natural differences in 13C abundances of: (1) C4 soil (with a history of C4 plant, Miscanthus sinensis, cultivation), (2) C3 soil (history of C3 plant cultivation), and (3) C4/3 soil (C4 soil, planted with a C3 plant, Triticum aestivum) were used. Total amounts and 13C values of total soil C, non-hydrolysable C, light fraction C, water-soluble C, microbial biomass C, and phospholipid fatty acids (PLFA) were determined. Using the 13C values of soil C in a mixing and a 1-box model enabled the quantification of relative contributions of C3 plant and C4 plant C to the total amount of the respective C pools in the C4/3 soil and their s. Compared to early spring (March), the percentage of C3 plant C increased in all pools in June and August, showing the addition of new C to the different soil C fractions. In August the contribution of new C to microbial biomass C and water-soluble C reached 64 and 89%, respectively. The s of these pools were 115 and 147 days. The 13C values of the dominant soil PLFA, 18:17c, cy19:0, 18:19c, 16:0, and 10Me16:0, showed wide ranges (–35.1 to –13.0) suggesting that the microbial community utilized different pools as C sources during the season. The 13C values of PLFA, therefore, enabled the analysis of the metabolically active populations. The majority of 13C values of PLFA from the C4/3 soil were closely related to those of PLFA from the C3 soil when T. aestivum biomass contributions to the soil were high in June and August. Specific populations reacted differently to changes in environmental conditions and supplies of C sources, which reflect the high functional diversity of soil microorganisms. |
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Keywords: | Carbon-13 Carbon dynamics Miscanthus Soil carbon Soil microbial biomass PLFA |
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