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Hardi Tullus - One of the best experts on this subject based on the ideXlab platform.
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the effect of land use type on net Nitrogen Mineralization on abandoned agricultural land silver birch stand versus grassland
Forest Ecology and Management, 2008Co-Authors: Veiko Uri, Krista Lohmus, Merit Kund, Hardi TullusAbstract:Abstract The effect of land use type on the dynamics and annual rate of net Nitrogen Mineralization (NNM) in a naturally generated silver birch stand and in a grassland, both on abandoned agricultural land, was assessed in situ in the upper 0–20 cm soil layer using the method of buried polyethylene bags. Annual NNM rate in the birch stand (156 kg N ha−1 year−1) was higher than in the grassland (102 kg N ha−1 year−1); in both cases NNM covered a major part of the plants annual Nitrogen demand. The rate of NNM in the upper 0–10 cm soil layer in the birch stand (99 kg N ha−1 year−1) exceeded the respective rate of NNM in the grassland (51 kg N ha−1 year−1) roughly two times. In the grassland the rates of NNM in the 0–10 and 10–20 cm layers were equal; in the birch stand NNM in the 0–10 cm layer was 1.7 times higher than in deeper 10–20 cm layer. The intensity of daily NNM in the upper 0–10 cm soil layer in the birch stand was the highest in June and in the grassland in May, 776 and 528 mg kg−1 N day−1, respectively. In our study no significant correlation was found between NNM and the environmental factors monthly mean soil temperature, soil moisture content and pH. The share of net nitrification in NNM in the birch stand and in the grassland was similar, 60% and 63%, respectively. In the deeper topsoil layer (10–20 cm) net nitrification made up a significantly higher proportion in NNM in the grassland than in the birch stand, 58% and 35%, respectively; this may increase Nitrogen leaching from the deeper soil layers. Most probably, more intensive NNM did not lead to higher N leaching or emission losses from ecosystems in the birch stand compared with the grassland because an essential amount of Nitrogen is retained in tree biomass.
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annual net Nitrogen Mineralization in a grey alder alnus incana l moench plantation on abandoned agricultural land
Forest Ecology and Management, 2003Co-Authors: Veiko Uri, Krista Lohmus, Hardi TullusAbstract:Abstract The dynamics and annual rate of net Nitrogen Mineralization in a grey alder plantation growing on abandoned agricultural land was assessed in situ using the method of buried polyethylene bags. Nitrogen Mineralization was assessed in the upper 0–10 and 10–20 cm soil layers, where 47.5 and 26.3% of the fine roots, respectively, were situated. Net Nitrogen Mineralization was the highest in May and September, 314 and 306 mg kg −1 N per day, respectively. Annual net Nitrogen Mineralization and net nitrification in the upper 0–10 cm soil layer were estimated as 84 and 87 kg ha −1 per year, respectively. Annual net Nitrogen Mineralization in the upper 0–20 cm soil layer was estimated as 141 kg ha −1 , which accounted for 62% of the annual Nitrogen used by trees and the understorey vegetation. Among various environmental factors related to Mineralization, pH played a significant role.
Shuli Niu - One of the best experts on this subject based on the ideXlab platform.
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the stoichiometry of soil microbial biomass determines metabolic quotient of Nitrogen Mineralization
Environmental Research Letters, 2020Co-Authors: Zhaoqi Zeng, Dashuan Tian, Bingxue Wang, Jinsong Wang, Han Y H Chen, Changhui Wang, Ze Tang, Weinan Chen, Shuli NiuAbstract:Soil Nitrogen (N) Mineralization is crucial for the sustainability of available soil N and hence ecosystem productivity and functioning. Metabolic quotient of N Mineralization (Qmin), which is defined as net soil N Mineralization per unit of soil microbial biomass N, reflects the efficiency of soil N Mineralization. However, it is far from clear how soil Qmin changes and what are the controlling factors at the global scale. We compiled 871 observations of soil Qmin from 79 published articles across terrestrial ecosystems (croplands, forests, grasslands, and wetlands) to elucidate the global variation of soil Qmin and its predictors. Soil Qmin decreased from the equator to two poles, which was significant in the North Hemisphere. Soil Qmin correlated negatively with soil pH, total soil N, the ratio of soil carbon (C) to N, and soil microbial biomass C, and positively with mean annual temperature and C: N ratio of soil microbial biomass at a global scale. Soil microbial biomass, climate, and soil physical and chemical properties in combination accounted for 41% of the total variation of global soil Qmin. Among those predictors, C: N ratio of soil microbial biomass was the most important factor contributing to the variations of soil Qmin (the standardized coefficient = 0.39) within or across ecosystem types. This study emphasizes the critical role of microbial stoichiometry in soil N cycling, and suggests the necessity of incorporating soil Qmin into Earth system models to better predict N cycling under environmental change.
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microbes drive global soil Nitrogen Mineralization and availability
Global Change Biology, 2019Co-Authors: Dashuan Tian, Bingxue Wang, Jinsong Wang, Song Wang, Han Y H Chen, Changhui Wang, Shuli NiuAbstract:Soil net Nitrogen Mineralization rate (Nmin ), which is critical for soil Nitrogen availability and plant growth, is thought to be primarily controlled by climate and soil physical and/or chemical properties. However, the role of microbes on regulating soil Nmin has not been evaluated on the global scale. By compiling 1565 observational data points of potential net Nmin from 198 published studies across terrestrial ecosystems, we found that Nmin significantly increased with soil microbial biomass, total Nitrogen, and mean annual precipitation, but decreased with soil pH. The variation of Nmin was ascribed predominantly to soil microbial biomass on global and biome scales. Mean annual precipitation, soil pH, and total soil Nitrogen significantly influenced Nmin through soil microbes. The structural equation models (SEM) showed that soil substrates were the main factors controlling Nmin when microbial biomass was excluded. Microbe became the primary driver when it was included in SEM analysis. SEM with soil microbial biomass improved the Nmin prediction by 19% in comparison with that devoid of soil microbial biomass. The changes in Nmin contributed the most to global soil NH4 + -N variations in contrast to climate and soil properties. This study reveals the complex interactions of climate, soil properties, and microbes on Nmin and highlights the importance of soil microbial biomass in determining Nmin and Nitrogen availability across the globe. The findings necessitate accurate representation of microbes in Earth system models to better predict Nitrogen cycle under global change.
Weixin Cheng - One of the best experts on this subject based on the ideXlab platform.
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plant inputs mediate the linkage between soil carbon and net Nitrogen Mineralization
Science of The Total Environment, 2021Co-Authors: Xiuwei Zhang, Biao Zhu, Weixin ChengAbstract:Abstract Plant residue inputs play a crucial role in regulating soil carbon (C) stock and Nitrogen (N) availability in cropland. However, little is known regarding how plant inputs mediate the relationships between soil C and net N Mineralization, causing additional uncertainty in predicting ecosystem C and N dynamics. This study investigated the influences of long-term deprivation of plant inputs, short-term addition of maize straw and experimental warming on soil C and net N Mineralization and their relationships. We conducted an 815-day laboratory incubation experiment under 10 and 20 °C using soils from a long-term bare fallow plot (without plant inputs for 23 years) and its adjacent old field plot (with continuous plant inputs). Our results showed that long-term deprivation of plant inputs decreased soil net N Mineralization (per unit total N or TN) by 56% on average, but had minor effect on soil C Mineralization (per unit soil organic C). Soil C and net N Mineralization rates were positively correlated in the old field soil under 20 °C. However, soil C and net N Mineralization rates were not correlated in the bare fallow soil, mainly due to the low level of net N Mineralization. Moreover, soil C and net N Mineralization rates were significantly increased by the addition of maize straw in both land-use types. When net N Mineralization was 162 (or 159) μg N g−1 TN d−1, soil C and net N Mineralization rates were positively correlated owing to a greater microbial mining of N from soil organic matter (SOM). Further, elevated temperature increased soil C and net N Mineralization rates, and changed the relationships between soil C and net N Mineralization. Taken together, this study provides evidence that plant inputs mediate the relationships between soil C and net N Mineralization, and is thus critical in controlling ecosystem C and N cycling.
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rhizosphere priming effects on soil carbon and Nitrogen Mineralization
Soil Biology & Biochemistry, 2014Co-Authors: Biao Zhu, Jessica L M Gutknecht, Donald J Herman, Daniel Keck, Mary K Firestone, Weixin ChengAbstract:Living roots and their rhizodeposits affect microbial activity and soil carbon (C) and Nitrogen (N) Mineralization. This so-called rhizosphere priming effect (RPE) has been increasingly recognized recently. However, the magnitude of the RPE and its driving mechanisms remain elusive. Here we investigated the RPE of two plant species (soybean and sunflower) grown in two soil types (a farm or a prairie soil) and sampled at two phenological stages (vegetative and mature stages) over an 88-day period in a greenhouse experiment. We measured soil C Mineralization using a continuous 13C-labeling method, and quantified gross N Mineralization with a 15N-pool dilution technique. We found that living roots significantly enhanced soil C Mineralization, by 27–245%. This positive RPE on soil C Mineralization did not vary between the two soils or the two phenological stages, but was significantly greater in sunflower compared to soybean. The magnitude of the RPE was positively correlated with rhizosphere respiration rate across all treatments, suggesting the variation of RPE among treatments was likely caused by variations in root activity and rhizodeposit quantity. Moreover, living roots stimulated gross N Mineralization rate by 36–62% in five treatments, while they had no significant impact in the other three treatments. We also quantified soil microbial biomass and extracellular enzyme activity when plants were at the vegetative stage. Generally, living roots increased microbial biomass carbon by 0–28%, β-glucosidase activity by 19–56%, and oxidative enzyme activity by 0–46%. These results are consistent with the positive rhizosphere effect on soil C (45–79%) and N (10–52%) Mineralization measured at the same period. We also found significant positive relationships between β-glucosidase activity and soil C Mineralization rates and between oxidative enzyme activity and gross N Mineralization rates across treatments. These relationships provide clear evidence for the microbial activation hypothesis of RPE. Our results demonstrate that root–soil–microbial interactions can stimulate soil C and N Mineralization through rhizosphere effects. The relationships between the RPE and rhizosphere respiration rate and soil enzyme activity can be used for explicit representations of RPE in soil organic matter models.
Biao Zhu - One of the best experts on this subject based on the ideXlab platform.
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plant inputs mediate the linkage between soil carbon and net Nitrogen Mineralization
Science of The Total Environment, 2021Co-Authors: Xiuwei Zhang, Biao Zhu, Weixin ChengAbstract:Abstract Plant residue inputs play a crucial role in regulating soil carbon (C) stock and Nitrogen (N) availability in cropland. However, little is known regarding how plant inputs mediate the relationships between soil C and net N Mineralization, causing additional uncertainty in predicting ecosystem C and N dynamics. This study investigated the influences of long-term deprivation of plant inputs, short-term addition of maize straw and experimental warming on soil C and net N Mineralization and their relationships. We conducted an 815-day laboratory incubation experiment under 10 and 20 °C using soils from a long-term bare fallow plot (without plant inputs for 23 years) and its adjacent old field plot (with continuous plant inputs). Our results showed that long-term deprivation of plant inputs decreased soil net N Mineralization (per unit total N or TN) by 56% on average, but had minor effect on soil C Mineralization (per unit soil organic C). Soil C and net N Mineralization rates were positively correlated in the old field soil under 20 °C. However, soil C and net N Mineralization rates were not correlated in the bare fallow soil, mainly due to the low level of net N Mineralization. Moreover, soil C and net N Mineralization rates were significantly increased by the addition of maize straw in both land-use types. When net N Mineralization was 162 (or 159) μg N g−1 TN d−1, soil C and net N Mineralization rates were positively correlated owing to a greater microbial mining of N from soil organic matter (SOM). Further, elevated temperature increased soil C and net N Mineralization rates, and changed the relationships between soil C and net N Mineralization. Taken together, this study provides evidence that plant inputs mediate the relationships between soil C and net N Mineralization, and is thus critical in controlling ecosystem C and N cycling.
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rhizosphere priming effects on soil carbon and Nitrogen Mineralization
Soil Biology & Biochemistry, 2014Co-Authors: Biao Zhu, Jessica L M Gutknecht, Donald J Herman, Daniel Keck, Mary K Firestone, Weixin ChengAbstract:Living roots and their rhizodeposits affect microbial activity and soil carbon (C) and Nitrogen (N) Mineralization. This so-called rhizosphere priming effect (RPE) has been increasingly recognized recently. However, the magnitude of the RPE and its driving mechanisms remain elusive. Here we investigated the RPE of two plant species (soybean and sunflower) grown in two soil types (a farm or a prairie soil) and sampled at two phenological stages (vegetative and mature stages) over an 88-day period in a greenhouse experiment. We measured soil C Mineralization using a continuous 13C-labeling method, and quantified gross N Mineralization with a 15N-pool dilution technique. We found that living roots significantly enhanced soil C Mineralization, by 27–245%. This positive RPE on soil C Mineralization did not vary between the two soils or the two phenological stages, but was significantly greater in sunflower compared to soybean. The magnitude of the RPE was positively correlated with rhizosphere respiration rate across all treatments, suggesting the variation of RPE among treatments was likely caused by variations in root activity and rhizodeposit quantity. Moreover, living roots stimulated gross N Mineralization rate by 36–62% in five treatments, while they had no significant impact in the other three treatments. We also quantified soil microbial biomass and extracellular enzyme activity when plants were at the vegetative stage. Generally, living roots increased microbial biomass carbon by 0–28%, β-glucosidase activity by 19–56%, and oxidative enzyme activity by 0–46%. These results are consistent with the positive rhizosphere effect on soil C (45–79%) and N (10–52%) Mineralization measured at the same period. We also found significant positive relationships between β-glucosidase activity and soil C Mineralization rates and between oxidative enzyme activity and gross N Mineralization rates across treatments. These relationships provide clear evidence for the microbial activation hypothesis of RPE. Our results demonstrate that root–soil–microbial interactions can stimulate soil C and N Mineralization through rhizosphere effects. The relationships between the RPE and rhizosphere respiration rate and soil enzyme activity can be used for explicit representations of RPE in soil organic matter models.
Changhui Wang - One of the best experts on this subject based on the ideXlab platform.
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effects of precipitation change and Nitrogen addition on soil net n Mineralization in a saline alkaline grassland of northern shanxi province china
Journal of Applied Ecology, 2021Co-Authors: Yan Wang, Changhui Wang, Huajie Diao, Kuanhu Dong, Wei ZhaoAbstract:To explore the responses of soil net Nitrogen (N) Mineralization rate to precipitation varia-tion and Nitrogen deposition in salinized grassland, we set precipitation manipulation and Nitrogen addition experiments in the typical agro-pastoral ecotone saline-alkaline grassland of Northern Shanxi Province, China. The in situ soil net N Mineralization rate was determined by top-cover buried PVC cylinder from May to September in 2019. The results showed that there were seasonal dynamics in soil net N Mineralization rate. Soil net N Mineralization rate was not affected by increase/decrease precipitation (±50%), Nitrogen addition (10 g·m-2·a-1) or the combination of Nitrogen addition and increase 50% precipitation treatments. The combination of Nitrogen addition and 50% reduction of precipitation significantly improved soil net nitrification rate and net N mine-ralization rate by 10.8 and 8.6 times, respectively. Soil net Nitrogen Mineralization rate was positively related to soil water content, and negatively related to soil pH. The effects of Nitrogen addition on soil Nitrogen Mineralization rate were dependent on precipitation conditions. Soil water content and pH were important factors regulating soil net Nitrogen Mineralization rate in the saline-alkaline grassland of Northern Shanxi Province. Therefore, to roundly assess the response model of soil N mine-ralization process to global change, it is necessary to consider the interaction of precipitation changes and Nitrogen addition, and the soil physical and chemical properties of salinized grassland.
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the stoichiometry of soil microbial biomass determines metabolic quotient of Nitrogen Mineralization
Environmental Research Letters, 2020Co-Authors: Zhaoqi Zeng, Dashuan Tian, Bingxue Wang, Jinsong Wang, Han Y H Chen, Changhui Wang, Ze Tang, Weinan Chen, Shuli NiuAbstract:Soil Nitrogen (N) Mineralization is crucial for the sustainability of available soil N and hence ecosystem productivity and functioning. Metabolic quotient of N Mineralization (Qmin), which is defined as net soil N Mineralization per unit of soil microbial biomass N, reflects the efficiency of soil N Mineralization. However, it is far from clear how soil Qmin changes and what are the controlling factors at the global scale. We compiled 871 observations of soil Qmin from 79 published articles across terrestrial ecosystems (croplands, forests, grasslands, and wetlands) to elucidate the global variation of soil Qmin and its predictors. Soil Qmin decreased from the equator to two poles, which was significant in the North Hemisphere. Soil Qmin correlated negatively with soil pH, total soil N, the ratio of soil carbon (C) to N, and soil microbial biomass C, and positively with mean annual temperature and C: N ratio of soil microbial biomass at a global scale. Soil microbial biomass, climate, and soil physical and chemical properties in combination accounted for 41% of the total variation of global soil Qmin. Among those predictors, C: N ratio of soil microbial biomass was the most important factor contributing to the variations of soil Qmin (the standardized coefficient = 0.39) within or across ecosystem types. This study emphasizes the critical role of microbial stoichiometry in soil N cycling, and suggests the necessity of incorporating soil Qmin into Earth system models to better predict N cycling under environmental change.
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microbes drive global soil Nitrogen Mineralization and availability
Global Change Biology, 2019Co-Authors: Dashuan Tian, Bingxue Wang, Jinsong Wang, Song Wang, Han Y H Chen, Changhui Wang, Shuli NiuAbstract:Soil net Nitrogen Mineralization rate (Nmin ), which is critical for soil Nitrogen availability and plant growth, is thought to be primarily controlled by climate and soil physical and/or chemical properties. However, the role of microbes on regulating soil Nmin has not been evaluated on the global scale. By compiling 1565 observational data points of potential net Nmin from 198 published studies across terrestrial ecosystems, we found that Nmin significantly increased with soil microbial biomass, total Nitrogen, and mean annual precipitation, but decreased with soil pH. The variation of Nmin was ascribed predominantly to soil microbial biomass on global and biome scales. Mean annual precipitation, soil pH, and total soil Nitrogen significantly influenced Nmin through soil microbes. The structural equation models (SEM) showed that soil substrates were the main factors controlling Nmin when microbial biomass was excluded. Microbe became the primary driver when it was included in SEM analysis. SEM with soil microbial biomass improved the Nmin prediction by 19% in comparison with that devoid of soil microbial biomass. The changes in Nmin contributed the most to global soil NH4 + -N variations in contrast to climate and soil properties. This study reveals the complex interactions of climate, soil properties, and microbes on Nmin and highlights the importance of soil microbial biomass in determining Nmin and Nitrogen availability across the globe. The findings necessitate accurate representation of microbes in Earth system models to better predict Nitrogen cycle under global change.