Soil microbial carbon use efficiency (CUE), defined as the ratio of organic C allocated to growth over organic C taken up, strongly affects soil carbon (C) cycling. Despite the importance of the microbial CUE for the terrestrial C cycle, very little is known about how it is affected by nutrient availability. Therefore, we studied microbial CUE and microbial biomass turnover time in soils of a long-term fertilization experiment in a temperate grassland comprising five treatments (control, PK, NK, NP, NPK). Microbial CUE and the turnover of microbial biomass were determined using a novel substrate-independent method based on incorporation of 18O from labeled water into microbial DNA. Microbial respiration was 28-37% smaller in all three N treatments (NK, NP, and NPK) compared to the control, whereas the PK treatment did not affect microbial respiration. N-fertilization decreased microbial C uptake, while the microbial growth rate was not affected. Microbial CUE ranged between 0.31 and 0.45, and was 1.3- to 1.4-fold higher in the N-fertilized soils than in the control. The turnover time ranged between 80 and 113 days and was not significantly affected by fertilization. Net primary production (NPP) and the abundance of legumes differed strongly across the treatments, and the fungal:bacterial ratio was very low in all treatments. Structural equation modeling revealed that microbial CUE was exclusively controlled by N fertilization and that neither the abundance of legumes (as a proxy for the quality of the organic matter inputs) nor NPP (as a proxy for C inputs) had an effect on microbial CUE. Our results show that N fertilization did not only decrease microbial respiration, but also microbial C uptake, indicating that less C was intracellularly processed in the N fertilized soils. The reason for reduced C uptake and increased CUE in the N-fertilization treatments is likely an inhibition of oxidative enzymes involved in the degradation of aromatic compounds by N in combination with a reduced energy requirement for microbial N acquisition in the fertilized soils. In conclusion, the study shows that N availability can control soil C cycling by affecting microbial CUE, while plant community-mediated changes in organic matter inputs and P and K availability played no important role for C partitioning of the microbial community in this temperate grassland.
", "keywords": ["FUNGAL", "2. Zero hunger", "106022 Mikrobiologie", "Nitrogen addition", "BACTERIAL", "NITROGEN DEPOSITION", "GROWTH EFFICIENCY", "FOREST FLOOR", "Nutrients", "04 agricultural and veterinary sciences", "15. Life on land", "Stoichiometry", "ORGANIC-MATTER", "RESPIRATION", "106026 \u00d6kosystemforschung", "13. Climate action", "Nutrient limitation", "Microbial growth yield", "106022 Microbiology", "0401 agriculture", " forestry", " and fisheries", "Mean residence time", "STOICHIOMETRIC CONTROLS", "ENZYME-ACTIVITY", "106026 Ecosystem research", "COMMUNITY STRUCTURE"]}, "links": [{"href": "https://doi.org/10.1016/j.soilbio.2016.03.008"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Soil%20Biology%20and%20Biochemistry", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.soilbio.2016.03.008", "name": "item", "description": "10.1016/j.soilbio.2016.03.008", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.soilbio.2016.03.008"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2016-06-01T00:00:00Z"}}, {"id": "10.1023/a:1004518730970", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-25T16:17:33Z", "type": "Journal Article", "created": "2002-12-21", "description": "Elevated atmospheric CO2 has the potential to change below-ground nutrient cycling and thereby alter the soil-atmosphere exchange of biogenic trace gases. We measured fluxes of CH4 and N2O in trembling aspen (Populus tremuloides Michx.) stands grown in open-top chambers under ambient and twice-ambient CO2 concentrations crossed with \u2018high\u2019 and low soil-N conditions.", "keywords": ["measurement-", "nitrous-oxide", "flux-", "Vascular-Plants", "poplars-", "carbon-dioxide-enrichment", "photosynthesis-", "Nutrition-", "carbon-dioxide: atmospheric-concentration", "stand-growth", "nitrogen-cycle", "michigan-", "methane-: flux-", "soil-", "nitrogen-", "Populus-tremuloides [aspen-] (Salicaceae-)", "carbon-cycle", "methane-production", "soil-fertility", "Salicaceae-: Dicotyledones-", "populus-tremuloides", "cycling-", "Spermatophytes-", "Spermatophyta-", "Plantae-", "biological-activity-in-soil", "Climatology- (Environmental-Sciences)", "Angiosperms-", "Angiospermae-", "Plants-", "gases-", "oxidation-", "forest-soils", "methane-", "04 agricultural and veterinary sciences", "GLOBAL-ECOLOGY", "15. Life on land", "enzyme-activity", "gas-exchange", "nitrous-oxide: emission-", "soil-water", "13. Climate action", "denitrification-", "0401 agriculture", " forestry", " and fisheries", "soil-bacteria", "Dicots-", "efflux-"]}, "links": [{"href": "https://doi.org/10.1023/a:1004518730970"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Plant%20and%20Soil", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1023/a:1004518730970", "name": "item", "description": "10.1023/a:1004518730970", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1023/a:1004518730970"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1999-02-01T00:00:00Z"}}, {"id": "10.1111/gcb.12996", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-25T16:18:44Z", "type": "Journal Article", "created": "2015-06-05", "title": "Microbial Physiology And Soil Co2 Efflux After 9 Years Of Soil Warming In A Temperate Forest - No Indications For Thermal Adaptations", "description": "AbstractThermal adaptations of soil microorganisms could mitigate or facilitate global warming effects on soil organic matter (SOM) decomposition and soil CO2 efflux. We incubated soil from warmed and control subplots of a forest soil warming experiment to assess whether 9\uffc2\uffa0years of soil warming affected the rates and the temperature sensitivity of the soil CO2 efflux, extracellular enzyme activities, microbial efficiency, and gross N mineralization. Mineral soil (0\uffe2\uff80\uff9310\uffc2\uffa0cm depth) was incubated at temperatures ranging from 3 to 23\uffc2\uffa0\uffc2\uffb0C. No adaptations to long\uffe2\uff80\uff90term warming were observed regarding the heterotrophic soil CO2 efflux (R10 warmed: 2.31\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.15\uffc2\uffa0\uffce\uffbcmol\uffc2\uffa0m\uffe2\uff88\uff922\uffc2\uffa0s\uffe2\uff88\uff921, control: 2.34\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.29\uffc2\uffa0\uffce\uffbcmol\uffc2\uffa0m\uffe2\uff88\uff922\uffc2\uffa0s\uffe2\uff88\uff921; Q10 warmed: 2.45\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.06, control: 2.45\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.04). Potential enzyme activities increased with incubation temperature, but the temperature sensitivity of the enzymes did not differ between the warmed and the control soils. The ratio of C\uffc2\uffa0:\uffc2\uffa0N acquiring enzyme activities was significantly higher in the warmed soil. Microbial biomass\uffe2\uff80\uff90specific respiration rates increased with incubation temperature, but the rates and the temperature sensitivity (Q10 warmed: 2.54\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.23, control 2.75\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.17) did not differ between warmed and control soils. Microbial substrate use efficiency (SUE) declined with increasing incubation temperature in both, warmed and control, soils. SUE and its temperature sensitivity (Q10 warmed: 0.84\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.03, control: 0.88\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.01) did not differ between warmed and control soils either. Gross N mineralization was invariant to incubation temperature and was not affected by long\uffe2\uff80\uff90term soil warming. Our results indicate that thermal adaptations of the microbial decomposer community are unlikely to occur in C\uffe2\uff80\uff90rich calcareous temperate forest soils.
", "keywords": ["0106 biological sciences", "570", "substrate use efficiency", "Nitrogen", "ARCTIC SOIL", "Acclimatization", "Forests", "soil CO2 efflux", "Global Warming", "01 natural sciences", "630", "COMMUNITY COMPOSITION", "BOREAL FOREST", "Soil", "gross N mineralization", "SEASONAL PATTERNS", "thermal adaptation", "EXTRACELLULAR ENZYMES", "CARBON-USE EFFICIENCY", "soil warming", "Enzyme activities", "BEECH FOREST", "ENZYME-ACTIVITY", "Soil Microbiology", "2. Zero hunger", "106022 Mikrobiologie", "Soil CO efflux", "NITROGEN AVAILABILITY", "04 agricultural and veterinary sciences", "Carbon Dioxide", "15. Life on land", "Primary Research Articles", "Thermal adaptation", "enzyme activities", "13. Climate action", "Austria", "106022 Microbiology", "Soil warming", "0401 agriculture", " forestry", " and fisheries", "CYCLE FEEDBACKS", "Gross N mineralization", "Seasons", "Substrate use efficiency"]}, "links": [{"href": "https://doi.org/10.1111/gcb.12996"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Global%20Change%20Biology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1111/gcb.12996", "name": "item", "description": "10.1111/gcb.12996", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1111/gcb.12996"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2015-09-28T00:00:00Z"}}, {"id": "2309129852", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-25T16:25:46Z", "type": "Journal Article", "created": "2016-03-26", "title": "Soil microbial carbon use efficiency and biomass turnover in a long-term fertilization experiment in a temperate grassland", "description": "Soil microbial carbon use efficiency (CUE), defined as the ratio of organic C allocated to growth over organic C taken up, strongly affects soil carbon (C) cycling. Despite the importance of the microbial CUE for the terrestrial C cycle, very little is known about how it is affected by nutrient availability. Therefore, we studied microbial CUE and microbial biomass turnover time in soils of a long-term fertilization experiment in a temperate grassland comprising five treatments (control, PK, NK, NP, NPK). Microbial CUE and the turnover of microbial biomass were determined using a novel substrate-independent method based on incorporation of 18O from labeled water into microbial DNA. Microbial respiration was 28-37% smaller in all three N treatments (NK, NP, and NPK) compared to the control, whereas the PK treatment did not affect microbial respiration. N-fertilization decreased microbial C uptake, while the microbial growth rate was not affected. Microbial CUE ranged between 0.31 and 0.45, and was 1.3- to 1.4-fold higher in the N-fertilized soils than in the control. The turnover time ranged between 80 and 113 days and was not significantly affected by fertilization. Net primary production (NPP) and the abundance of legumes differed strongly across the treatments, and the fungal:bacterial ratio was very low in all treatments. Structural equation modeling revealed that microbial CUE was exclusively controlled by N fertilization and that neither the abundance of legumes (as a proxy for the quality of the organic matter inputs) nor NPP (as a proxy for C inputs) had an effect on microbial CUE. Our results show that N fertilization did not only decrease microbial respiration, but also microbial C uptake, indicating that less C was intracellularly processed in the N fertilized soils. The reason for reduced C uptake and increased CUE in the N-fertilization treatments is likely an inhibition of oxidative enzymes involved in the degradation of aromatic compounds by N in combination with a reduced energy requirement for microbial N acquisition in the fertilized soils. In conclusion, the study shows that N availability can control soil C cycling by affecting microbial CUE, while plant community-mediated changes in organic matter inputs and P and K availability played no important role for C partitioning of the microbial community in this temperate grassland.
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