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": "10.1111/gcb.16042", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-26T16:18:35Z", "type": "Journal Article", "created": "2021-12-19", "title": "Stimulation of ammonia oxidizer and denitrifier abundances by nitrogen loading: Poor predictability for increased soil N2O emission", "description": "AbstractUnprecedented nitrogen (N) inputs into terrestrial ecosystems have profoundly altered soil N cycling. Ammonia oxidizers and denitrifiers are the main producers of nitrous oxide (N2O), but it remains unclear how ammonia oxidizer and denitrifier abundances will respond to N loading and whether their responses can predict N\uffe2\uff80\uff90induced changes in soil N2O emission. By synthesizing 101 field studies worldwide, we showed that N loading significantly increased ammonia oxidizer abundance by 107% and denitrifier abundance by 45%. The increases in both ammonia oxidizer and denitrifier abundances were primarily explained by N loading form, and more specifically, organic N loading had stronger effects on their abundances than mineral N loading. Nitrogen loading increased soil N2O emission by 261%, whereas there was no clear relationship between changes in soil N2O emission and shifts in ammonia oxidizer and denitrifier abundances. Our field\uffe2\uff80\uff90based results challenge the laboratory\uffe2\uff80\uff90based hypothesis that increased ammonia oxidizer and denitrifier abundances by N loading would directly cause higher soil N2O emission. Instead, key abiotic factors (mean annual precipitation, soil pH, soil C:N ratio, and ecosystem type) explained N\uffe2\uff80\uff90induced changes in soil N2O emission. Altogether, these findings highlight the need for considering the roles of key abiotic factors in regulating soil N transformations under N loading to better understand the microbially mediated soil N2O emission.Emerging evidence points out that the responses of soil organic carbon (SOC) to nitrogen (N) addition differ along the soil profile, highlighting the importance of synthesizing results from different soil layers. Here, using a global meta\uffe2\uff80\uff90analysis, we found that N addition significantly enhanced topsoil (0\uffe2\uff80\uff9330\uffe2\uff80\uff89cm) SOC by 3.7% (\uffc2\uffb11.4%) in forests and grasslands. In contrast, SOC in the subsoil (30\uffe2\uff80\uff93100\uffe2\uff80\uff89cm) initially increased with N addition but decreased over time. The model selection analysis revealed that experimental duration and vegetation type are among the most important predictors across a wide range of climatic, environmental, and edaphic variables. The contrasting responses of SOC to N addition indicate the importance of considering deep soil layers, particularly for long\uffe2\uff80\uff90term continuous N deposition. Finally, the lack of depth\uffe2\uff80\uff90dependent SOC responses to N addition in experimental and modeling frameworks has likely resulted in the overestimation of changes in SOC storage under enhanced N deposition.Increased human\uffe2\uff80\uff90derived nitrogen (N) deposition to terrestrial ecosystems has resulted in widespread phosphorus (P) limitation of net primary productivity. However, it remains unclear if and how N\uffe2\uff80\uff90induced P limitation varies over time. Soil extracellular phosphatases catalyze the hydrolysis of P from soil organic matter, an important adaptive mechanism for ecosystems to cope with N\uffe2\uff80\uff90induced P limitation. Here we show, using a meta\uffe2\uff80\uff90analysis of 140 studies and 668 observations worldwide, that N stimulation of soil phosphatase activity diminishes over time. Whereas short\uffe2\uff80\uff90term N loading (\uffe2\uff89\uffa45\uffc2\uffa0years) significantly increased soil phosphatase activity by 28%, long\uffe2\uff80\uff90term N loading had no significant effect. Nitrogen loading did not affect soil available P and total P content in either short\uffe2\uff80\uff90 or long\uffe2\uff80\uff90term studies. Together, these results suggest that N\uffe2\uff80\uff90induced P limitation in ecosystems is alleviated in the long\uffe2\uff80\uff90term through the initial stimulation of soil phosphatase activity, thereby securing P supply to support plant growth. Our results suggest that increases in terrestrial carbon uptake due to ongoing anthropogenic N loading may be greater than previously thought.Anthropogenic nitrogen (N) loading alters soil ammonia\uffe2\uff80\uff90oxidizing archaea (AOA) and bacteria (AOB) abundances, likely leading to substantial changes in soil nitrification. However, the factors and mechanisms determining the responses of soil AOA:AOB and nitrification to N loading are still unclear, making it difficult to predict future changes in soil nitrification. Herein, we synthesize\uffc2\uffa068 field studies around the world to evaluate the impacts of N loading on soil ammonia oxidizers and nitrification. Across a wide range of biotic and abiotic factors, climate is the most important driver of the responses of AOA:AOB to N loading. Climate does not directly affect the N\uffe2\uff80\uff90stimulation of nitrification, but does so via climate\uffe2\uff80\uff90related shifts in AOA:AOB. Specifically, climate modulates the responses of AOA:AOB to N loading by affecting soil pH, N\uffe2\uff80\uff90availability and moisture. AOB play a dominant role in affecting nitrification in dry climates, while the impacts from AOA can exceed AOB in humid climates. Together, these results suggest that climate\uffe2\uff80\uff90related shifts in soil ammonia\uffe2\uff80\uff90oxidizing community maintain the N\uffe2\uff80\uff90stimulation of nitrification, highlighting the importance of microbial community composition in mediating the responses of the soil N cycle to N loading.Predicting species responses to climate change and land use practices requires understanding both the direct effects of environmental factors as well as the indirect effects mediated by changes in belowground and aboveground competition. Belowground root competition from surrounding vegetation and aboveground light competition are two important factors affecting seedling establishment. However, few studies have jointly examined the effect of belowground root and light competition on seedling establishment, especially under long-term nitrogen addition and mowing. Here, we examined how belowground root competition from surrounding vegetation and aboveground light competition affect seedling establishment within a long-term nitrogen addition and mowing experiment. Seedlings of two grasses (Stipa krylovii and Cleistogenes squarrosa) were grown with and without belowground root competition under control, nitrogen addition, and mowing treatments, and their growth characteristics were monitored. The seedlings of the two grasses achieved higher total biomass, height, mean shoot and root mass, but a lower root/shoot ratio in the absence than in the presence of belowground root competition. Nitrogen addition significantly decreased shoot biomass, root biomass, and the survival of the two grasses. Regression analyses revealed that the biomass of the two grass was strongly negatively correlated with net primary productivity under belowground root competition, but with the intercept photosynthetic active radiation in the absence of belowground root competition. This experiment demonstrates that belowground root competition can alter the grass seedling establishment response to light in a long-term nitrogen addition and mowing experiment.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/2309129852"}, {"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": "2309129852", "name": "item", "description": "2309129852", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/2309129852"}, {"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": "10261/356392", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-26T16:24:39Z", "type": "Journal Article", "created": "2021-12-19", "title": "Stimulation of ammonia oxidizer and denitrifier abundances by nitrogen loading: Poor predictability for increased soil N2O emission", "description": "AbstractUnprecedented nitrogen (N) inputs into terrestrial ecosystems have profoundly altered soil N cycling. Ammonia oxidizers and denitrifiers are the main producers of nitrous oxide (N2O), but it remains unclear how ammonia oxidizer and denitrifier abundances will respond to N loading and whether their responses can predict N\uffe2\uff80\uff90induced changes in soil N2O emission. By synthesizing 101 field studies worldwide, we showed that N loading significantly increased ammonia oxidizer abundance by 107% and denitrifier abundance by 45%. The increases in both ammonia oxidizer and denitrifier abundances were primarily explained by N loading form, and more specifically, organic N loading had stronger effects on their abundances than mineral N loading. Nitrogen loading increased soil N2O emission by 261%, whereas there was no clear relationship between changes in soil N2O emission and shifts in ammonia oxidizer and denitrifier abundances. Our field\uffe2\uff80\uff90based results challenge the laboratory\uffe2\uff80\uff90based hypothesis that increased ammonia oxidizer and denitrifier abundances by N loading would directly cause higher soil N2O emission. Instead, key abiotic factors (mean annual precipitation, soil pH, soil C:N ratio, and ecosystem type) explained N\uffe2\uff80\uff90induced changes in soil N2O emission. Altogether, these findings highlight the need for considering the roles of key abiotic factors in regulating soil N transformations under N loading to better understand the microbially mediated soil N2O emission.Increased human\uffe2\uff80\uff90derived nitrogen (N) deposition to terrestrial ecosystems has resulted in widespread phosphorus (P) limitation of net primary productivity. However, it remains unclear if and how N\uffe2\uff80\uff90induced P limitation varies over time. Soil extracellular phosphatases catalyze the hydrolysis of P from soil organic matter, an important adaptive mechanism for ecosystems to cope with N\uffe2\uff80\uff90induced P limitation. Here we show, using a meta\uffe2\uff80\uff90analysis of 140 studies and 668 observations worldwide, that N stimulation of soil phosphatase activity diminishes over time. Whereas short\uffe2\uff80\uff90term N loading (\uffe2\uff89\uffa45\uffc2\uffa0years) significantly increased soil phosphatase activity by 28%, long\uffe2\uff80\uff90term N loading had no significant effect. Nitrogen loading did not affect soil available P and total P content in either short\uffe2\uff80\uff90 or long\uffe2\uff80\uff90term studies. Together, these results suggest that N\uffe2\uff80\uff90induced P limitation in ecosystems is alleviated in the long\uffe2\uff80\uff90term through the initial stimulation of soil phosphatase activity, thereby securing P supply to support plant growth. Our results suggest that increases in terrestrial carbon uptake due to ongoing anthropogenic N loading may be greater than previously thought.Anthropogenic nitrogen (N) loading alters soil ammonia\uffe2\uff80\uff90oxidizing archaea (AOA) and bacteria (AOB) abundances, likely leading to substantial changes in soil nitrification. However, the factors and mechanisms determining the responses of soil AOA:AOB and nitrification to N loading are still unclear, making it difficult to predict future changes in soil nitrification. Herein, we synthesize\uffc2\uffa068 field studies around the world to evaluate the impacts of N loading on soil ammonia oxidizers and nitrification. Across a wide range of biotic and abiotic factors, climate is the most important driver of the responses of AOA:AOB to N loading. Climate does not directly affect the N\uffe2\uff80\uff90stimulation of nitrification, but does so via climate\uffe2\uff80\uff90related shifts in AOA:AOB. Specifically, climate modulates the responses of AOA:AOB to N loading by affecting soil pH, N\uffe2\uff80\uff90availability and moisture. AOB play a dominant role in affecting nitrification in dry climates, while the impacts from AOA can exceed AOB in humid climates. Together, these results suggest that climate\uffe2\uff80\uff90related shifts in soil ammonia\uffe2\uff80\uff90oxidizing community maintain the N\uffe2\uff80\uff90stimulation of nitrification, highlighting the importance of microbial community composition in mediating the responses of the soil N cycle to N loading.Emerging evidence points out that the responses of soil organic carbon (SOC) to nitrogen (N) addition differ along the soil profile, highlighting the importance of synthesizing results from different soil layers. Here, using a global meta\uffe2\uff80\uff90analysis, we found that N addition significantly enhanced topsoil (0\uffe2\uff80\uff9330\uffe2\uff80\uff89cm) SOC by 3.7% (\uffc2\uffb11.4%) in forests and grasslands. In contrast, SOC in the subsoil (30\uffe2\uff80\uff93100\uffe2\uff80\uff89cm) initially increased with N addition but decreased over time. The model selection analysis revealed that experimental duration and vegetation type are among the most important predictors across a wide range of climatic, environmental, and edaphic variables. The contrasting responses of SOC to N addition indicate the importance of considering deep soil layers, particularly for long\uffe2\uff80\uff90term continuous N deposition. Finally, the lack of depth\uffe2\uff80\uff90dependent SOC responses to N addition in experimental and modeling frameworks has likely resulted in the overestimation of changes in SOC storage under enhanced N deposition.Increased human\uffe2\uff80\uff90derived nitrogen (N) deposition to terrestrial ecosystems has resulted in widespread phosphorus (P) limitation of net primary productivity. However, it remains unclear if and how N\uffe2\uff80\uff90induced P limitation varies over time. Soil extracellular phosphatases catalyze the hydrolysis of P from soil organic matter, an important adaptive mechanism for ecosystems to cope with N\uffe2\uff80\uff90induced P limitation. Here we show, using a meta\uffe2\uff80\uff90analysis of 140 studies and 668 observations worldwide, that N stimulation of soil phosphatase activity diminishes over time. Whereas short\uffe2\uff80\uff90term N loading (\uffe2\uff89\uffa45\uffc2\uffa0years) significantly increased soil phosphatase activity by 28%, long\uffe2\uff80\uff90term N loading had no significant effect. Nitrogen loading did not affect soil available P and total P content in either short\uffe2\uff80\uff90 or long\uffe2\uff80\uff90term studies. Together, these results suggest that N\uffe2\uff80\uff90induced P limitation in ecosystems is alleviated in the long\uffe2\uff80\uff90term through the initial stimulation of soil phosphatase activity, thereby securing P supply to support plant growth. Our results suggest that increases in terrestrial carbon uptake due to ongoing anthropogenic N loading may be greater than previously thought.Unprecedented nitrogen (N) inputs into terrestrial ecosystems have profoundly altered soil N cycling. Ammonia oxidizers and denitrifiers are the main producers of nitrous oxide (N2O), but it remains unclear how ammonia oxidizer and denitrifier abundances will respond to N loading and whether their responses can predict N\uffe2\uff80\uff90induced changes in soil N2O emission. By synthesizing 101 field studies worldwide, we showed that N loading significantly increased ammonia oxidizer abundance by 107% and denitrifier abundance by 45%. The increases in both ammonia oxidizer and denitrifier abundances were primarily explained by N loading form, and more specifically, organic N loading had stronger effects on their abundances than mineral N loading. Nitrogen loading increased soil N2O emission by 261%, whereas there was no clear relationship between changes in soil N2O emission and shifts in ammonia oxidizer and denitrifier abundances. Our field\uffe2\uff80\uff90based results challenge the laboratory\uffe2\uff80\uff90based hypothesis that increased ammonia oxidizer and denitrifier abundances by N loading would directly cause higher soil N2O emission. Instead, key abiotic factors (mean annual precipitation, soil pH, soil C:N ratio, and ecosystem type) explained N\uffe2\uff80\uff90induced changes in soil N2O emission. Altogether, these findings highlight the need for considering the roles of key abiotic factors in regulating soil N transformations under N loading to better understand the microbially mediated soil N2O emission.Predicting species responses to climate change and land use practices requires understanding both the direct effects of environmental factors as well as the indirect effects mediated by changes in belowground and aboveground competition. Belowground root competition from surrounding vegetation and aboveground light competition are two important factors affecting seedling establishment. However, few studies have jointly examined the effect of belowground root and light competition on seedling establishment, especially under long-term nitrogen addition and mowing. Here, we examined how belowground root competition from surrounding vegetation and aboveground light competition affect seedling establishment within a long-term nitrogen addition and mowing experiment. Seedlings of two grasses (Stipa krylovii and Cleistogenes squarrosa) were grown with and without belowground root competition under control, nitrogen addition, and mowing treatments, and their growth characteristics were monitored. The seedlings of the two grasses achieved higher total biomass, height, mean shoot and root mass, but a lower root/shoot ratio in the absence than in the presence of belowground root competition. Nitrogen addition significantly decreased shoot biomass, root biomass, and the survival of the two grasses. Regression analyses revealed that the biomass of the two grass was strongly negatively correlated with net primary productivity under belowground root competition, but with the intercept photosynthetic active radiation in the absence of belowground root competition. This experiment demonstrates that belowground root competition can alter the grass seedling establishment response to light in a long-term nitrogen addition and mowing experiment.