Soil microbial biomass C:N:P stoichiometry and microbial use of organic phosphorus |
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| Affiliation: | 1. Department of Soil Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University Bayreuth, Dr.-Hans-Frisch-Str. 1-3, 95448 Bayreuth, Germany;2. Department of DNA Analytics and Ecoinformatics, Bayreuth Center of Ecology and Environmental Research (BayCEER), University Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany;1. State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 210008 Nanjing, PR China;2. University of Chinese Academy of Sciences, 100049 Beijing, PR China;1. Department of Earth System Science, University of California, Irvine, CA 92697, USA;2. Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA;1. Soil Biogeochemistry, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Germany;2. Forest Botany and Tree Physiology, Georg-August University of Göttingen, Germany;3. Laboratory for Radio-Isotopes, Georg-August University of Göttingen, Germany;4. Institute of Soil Science and Land Evaluation, Soil Biology Department, University of Hohenheim, Stuttgart, Germany;5. Research Unit Comparative Microbiome Analysis, Helmholtz Zentrum München, Germany;6. Chair for Soil Science, Technical University of Munich, Emil-Ramann-Str. 2, D-85354 Freising, Germany;1. Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, České Budějovice, Branišovská 31, 37011, Czech Republic;2. Biology Centre CAS, Institute of Hydrobiology, Na Sádkách 702/2, České Budějovice 37005, Czech Republic |
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| Abstract: | Microbial mineralization and immobilization of nutrients strongly influence soil fertility. We studied microbial biomass stoichiometry, microbial community composition, and microbial use of carbon (C) and phosphorus (P) derived from glucose-6-phosphate in the A and B horizons of two temperate Cambisols with contrasting P availability. In a first incubation experiment, C, nitrogen (N) and P were added to the soils in a full factorial design. Microbial biomass C, N and P concentrations were analyzed by the fumigation-extraction method and microbial community composition was analyzed by a community fingerprinting method (automated ribosomal intergenic spacer analysis, ARISA). In a second experiment, we compared microbial use of C and P from glucose-6-phosphate by adding 14C or 33P labeled glucose-6-phosphate to soil. In the first incubation experiment, the microbial biomass increased up to 30-fold due to addition of C, indicating that microbial growth was mainly C limited. Microbial biomass C:N:P stoichiometry changed more strongly due to element addition in the P-poor soils, than in the P-rich soils. The microbial community composition analysis showed that element additions led to stronger changes in the microbial community in the P-poor than in the P-rich soils. Therefore, the changed microbial biomass stoichiometry in the P-poor soils was likely caused by a shift in the microbial community composition. The total recovery of 14C derived from glucose-6-phosphate in the soil microbial biomass and in the respired CO2 ranged between 28.2 and 37.1% 66 h after addition of the tracer, while the recovery of 33P in the soil microbial biomass was 1.4–6.1%. This indicates that even in the P-poor soils microorganisms mineralized organic P and took up more C than P from the organic compound. Thus, microbial mineralization of organic P was driven by microbial need for C rather than for P. In conclusion, our experiments showed that (i) the microbial biomass stoichiometry in the P-poor soils was more susceptible to additions of C, N and P than in the P-rich soils and that (ii) even in the P-poor soils, microorganisms were C-limited and the mineralization of organic P was mainly driven by microbial C demand. |
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| Keywords: | Stoichiometry Soil microbial biomass Soil microbial community Organic phosphorus Temperate deciduous forest |
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