Deep soil C and N pools in long-term fenced and overgrazed temperate grasslands in northwest China

Abstract Fencing for grazing exclusion has been widely found to have an impact on grassland soil organic carbon (SOC) and total nitrogen (TN), but little is known about the impact of fenced grassland on the changes in deep soil carbon (C) and nitrogen (N) stocks in temperate grasslands. We studied the influence of 30 years fencing on vegetation and deep soil characteristics (0–500 cm) in the semi-arid grasslands of northern China. The results showed that fencing significantly increased the aboveground biomass (AGB), litter biomass (LB), total biomass, vegetation coverage and height, and soil water content and the SOC and TN in the deep soil. The belowground biomass (BGB) did not significantly differ between the fenced and grazed grassland. However, fencing significantly decreased the root/shoot ratio, forbs biomass, pH, and soil bulk density. Meanwhile, fencing has significantly increased the C and N stocks in the AGB and LB but not in the BGB. After 30 years of fencing, the C and N stocks significantly increased in the 0–500 cm soil layer. The accumulation of SOC mainly occurred in the deep layers (30–180 cm), and the accumulation of TN occurred in the soil layers of 0 to 60 cm and 160 to 500 cm. Our results indicate that fencing is an effective way to improve deep soil C and N stocks in temperate grassland of northwest China. There were large C and N stocks in the soil layers of 100 to 500 cm in the fenced grasslands, and their dynamics should not be ignored.

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Effects of fertilizer and biochar applications on the relationship among soil moisture, temperature, and N2O emissions in farmland

PeerJ ◽

10.7717/peerj.11674 ◽

2021 ◽

Vol 9 ◽

pp. e11674

Author(s):

Xiao Wang ◽

Ping Lu ◽

Peiling Yang ◽

Shumei Ren

Keyword(s):

Soil Moisture ◽

Soil Improvement ◽

Sensitivity Coefficient ◽

Exponential Model ◽

N2o Emissions ◽

Deep Soil ◽

Soil C ◽

Soil C And N ◽

C And N ◽

The Impact

Background Di-nitrogen oxide (N2O) emissions from soil may lead to nonpoint-source pollution in farmland. Improving the C and N content in the soil is an excellent strategy to reduce N2O emission and mitigate soil N loss. However, this method lacks a unified mathematical index or standard to evaluate its effect. Methods To quantify the impact of soil improvement (C and N) on N2O emissions, we conducted a 2-year field experiment using biochar as carbon source and fertilizer as nitrogen source, setting three treatments (fertilization (300 kg N ha−1), fertilization + biochar (30 t ha−1), control). Results Results indicate that after biochar application, the average soil water content above 20 cm increased by ∼26% and 26.92% in 2019, and ∼10% and 12.49% in 2020. The average soil temperature above 20 cm also increased by ∼2% and 3.41% in 2019. Fertigation significantly promotes the soil N2O emissions, and biochar application indeed inhibited the cumulation by approximately 52.4% in 2019 and 33.9% in 2020, respectively. N2O emissions strongly depend on the deep soil moisture and temperature (20–80 cm), in addition to the surface soil moisture and temperature (0–20 cm). Therefore, we established an exponential model between the soil moisture and N2O emissions based on theoretical analysis. We find that the N2O emissions exponentially increase with increasing soil moisture regardless of fertilization or biochar application. Furthermore, the coefficient a < 0 means that N2O emissions initially increase and then decrease. The aRU < aCK indicates that fertilization does promote the rate of N2O emissions, and the aBRU > aRU indicates that biochar application mitigates this rate induced by fertilization. This conclusion can be verified by the sensitivity coefficient (SCB of 1.02 and 14.74; SCU of 19.18 and 20.83). Thus, we believe the model can quantify the impact of soil C and N changes on N2O emissions. We can conclude that biochar does significantly reduce N2O emissions from farmland.

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Effect of elevated tropospheric ozone on soil carbon and nitrogen: A meta-analysis

Environmental Research Letters ◽

10.1088/1748-9326/ac49b9 ◽

2022 ◽

Author(s):

Enzhu Hu ◽

Zhimin Ren ◽

Xiaoke Wang ◽

Hongxing Zhang ◽

Weiwei Zhang

Keyword(s):

Tropospheric Ozone ◽

Terrestrial Ecosystem ◽

Soil N ◽

N Dynamics ◽

Organic C ◽

Soil C ◽

Soil C And N ◽

C And N ◽

The Impact ◽

C And N Dynamics

Abstract Elevated tropospheric ozone concentration ([O3]) may substantially influence the belowground processes of the terrestrial ecosystem. Nevertheless, a comprehensive and quantitative understanding of the responses of soil C and N dynamics to elevated [O3] remains elusive. In this study, the results of 41 peer-reviewed studies were synthesized using meta-analytic techniques, to quantify the impact of O3 on ten variables associated with soil C and N, i.e., total C (TC, including soil organic C), total N (TN), dissolved organic C (DOC), ammonia N (NH4 +), nitrate N (NO3 -), microbial biomass C (MBC) and N (MBN), rates of nitrification (NTF) and denitrification (DNF), as well as C/N ratio. The results depicted that all these variables showed significant changes (P < 0.05) with [O3] increased by 27.6 ± 18.7 nL/L (mean ± SD), including decreases in TC, DOC, TN, NH4 +, MBC, MBN and NTF, and increases in C/N, NO3 - and DNF. The effect sizes of TN, NTF, and DNF were significantly correlated with O3 fumigation level and experimental duration (P < 0.05). Soil pH and climate were essential in analyses of O3 impacts on soil C and N. However, the responses of most variables to elevated [O3] were generally independent of O3 fumigation method, terrestrial ecosystem type, and additional [CO2] exposure. The altered soil C and N dynamics under elevated [O3] may reduce its C sink capacity, and change soil N availability thus impact plant growth and enhance soil N losses.

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Soil C and N Content Under Evolving Landscapes in an Arid Inland River Basin of Northwest China

Landscape Ecology ◽

10.1023/b:land.0000042896.93494.ed ◽

2004 ◽

Vol 19 (6) ◽

pp. 621-629 ◽

Cited By ~ 4

Author(s):

Wang Genxu ◽

Yao Jinzhong ◽

Luo Lin ◽

Qian Ju

Keyword(s):

River Basin ◽

Northwest China ◽

N Content ◽

Soil C ◽

Inland River ◽

Inland River Basin ◽

Soil C And N ◽

C And N

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Afforestation With Tropical N-Fixing Species in The Brazilian Atlantic Rainforest: Carbon and Nitrogen in The Soil Profile

10.21203/rs.3.rs-594747/v1 ◽

2021 ◽

Author(s):

David Pessanha Siqueira ◽

Emanuela Forestieri Gama-Rodrigues ◽

Marcos Vinícius Winckler Caldeira ◽

Carlos Eduardo Rezende ◽

Claudio Roberto Marciano ◽

...

Keyword(s):

Soil Profile ◽

Soil Depth ◽

Mineral Soil ◽

Species Traits ◽

Atlantic Rainforest ◽

Opposite Pattern ◽

Soil Layers ◽

Soil C ◽

Soil C And N ◽

C And N

Abstract Aims Atlantic Rainforest biome is one of the most threatened in the world by deforestation where afforestation programs are urgently needed. N-fixing species should be prioritized in re-establishing forest covers as they can enhance soil C and N and stimulate cycling of other nutrients. Yet, tropical ecosystems play a key role in global warming and remain underestimated in the global biogeochemical balances. We aimed to investigate the effects of tropical N-fixing species on soil C and N pools after pasture conversionMethods We selected: Plathymenia reticulata, Hymenaea courbaril, and Centrolobium tomentosum 27-year-old monospecific stands. We evaluated soil organic carbon (SOC), nitrogen (STN), and the natural abundance of 13C and 15N in the soil profile up to 100 cm depth. Results SOC was higher for P. reticulata, but an opposite pattern was observed when combining only soil layers up to 30 cm soil depth. Meanwhile, STN was similar across species and d15N values showed enrichment at intermediate soil layers indicating 14N gaseous loss. Most of the SOC originated from the planted trees rather than the former pasture, except beneath C. tomentosum where C4 derived C is decreasing at a slower rate. Conclusion This study presents novel insights in the understanding of tropical N-fixing species effects on soil C and N where specific-species traits appear to mediate SOC retention to the mineral soil rather than the N-fixing ability per se.

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Soil carbon and nitrogen in pasture soil reforested with eucalyptus and guachapele

Revista Brasileira de Ciência do Solo ◽

10.1590/s0100-06832008000300033 ◽

2008 ◽

Vol 32 (3) ◽

pp. 1253-1260 ◽

Cited By ~ 33

Author(s):

Fabiano de Carvalho Balieiro ◽

Marcos Gervasio Pereira ◽

Bruno José Rodrigues Alves ◽

Alexander Silva de Resende ◽

Avílio Antonio Franco

Keyword(s):

Panicum Maximum ◽

Soil Organic C ◽

Total N ◽

Organic C ◽

Soil C ◽

C Stocks ◽

Soil C And N ◽

C And N ◽

Mixed Plantation ◽

The Impact

In spite of the normally low content of organic matter found in sandy soils, it is responsible for almost the totality of cation exchange capacity (CEC), water storage and availability of plant nutrients. It is therefore important to evaluate the impact of alternative forest exploitation on the improvement of soil C and N accumulation on these soils. This study compared pure and mixed plantations of Eucalyptus grandis and Pseudosamanea guachapele, a N2-fixing leguminous tree, in relation to their effects on soil C and N stocks. The studied Planosol area had formerly been covered by Panicum maximum pasture for at least ten years without any fertilizer addition. To estimate C and N contents, the soil was sampled (at depths of 0-2.5; 2.5-5.0; 5.0-7.5; 7.5-10.0; 10.0-20.0 and 20.0-40.0 cm), in pure and mixed five-year-old tree plantations, as well as on adjacent pasture. The natural abundance 13C technique was used to estimate the contribution of the soil organic C originated from the trees in the 0-10 cm soil layer. Soil C and N stocks under mixed plantation were 23.83 and 1.74 Mg ha-1, respectively. Under guachapele, eucalyptus and pasture areas C stocks were 14.20, 17.19 and 24.24 Mg ha-1, respectively. For these same treatments, total N contents were 0.83; 0.99 and 1.71 Mg ha-1, respectively. Up to 40 % of the soil organic C in the mixed plantation was estimated to be derived from trees, while in pure eucalyptus and guachapele plantations these same estimates were only 19 and 27 %, respectively. Our results revealed the benefits of intercropped leguminous trees in eucalyptus plantations on soil C and N stocks.

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The Impact of Elevated Atmospheric [CO2] on Soil C and N Dynamics: A Meta-Analysis

Managed Ecosystems and CO2 - Ecological Studies ◽

10.1007/3-540-31237-4_21 ◽

2006 ◽

pp. 373-391 ◽

Cited By ~ 13

Author(s):

K. -J. van Groenigen ◽

M. -A. de Graaff ◽

J. Six ◽

D. Harris ◽

P. Kuikman ◽

...

Keyword(s):

Meta Analysis ◽

Atmospheric Co2 ◽

N Dynamics ◽

Soil C ◽

Elevated Atmospheric Co2 ◽

Soil C And N ◽

C And N ◽

The Impact ◽

C And N Dynamics

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Assessing the Impact of Soil Moisture on Canopy Transpiration Using a Modified Jarvis-Stewart Model

Water ◽

10.3390/w13192720 ◽

2021 ◽

Vol 13 (19) ◽

pp. 2720

Author(s):

Songping Yu ◽

Jianbin Guo ◽

Zebin Liu ◽

Yanhui Wang ◽

Jing Ma ◽

...

Keyword(s):

Soil Moisture ◽

Environmental Influence ◽

Soil Layer ◽

Northwest China ◽

Limiting Factor ◽

Flow Measurements ◽

Area Index ◽

Soil Layers ◽

Canopy Transpiration ◽

The Impact

In dryland regions, soil moisture is an important limiting factor for canopy transpiration (T). Thus, clarifying the impact of soil moisture on T is critical for comprehensive forest—water management and sustainable development. In this study, T, meteorological factors (reference evapotranspiration, ETref), soil moisture (relative soil water content, RSWC), and leaf area index (LAI) in a Larix principis-rupprechtii plantation of Liupan Mountains in the dryland region of Northwest China were simultaneously monitored during the growing seasons in 2017–2019. A modified Jarvis—Stewart model was established by introducing the impact of RSWC in different soil layers (0–20, 20–40, and 40–60 cm, respectively) to quantify the independent contribution of RSWC of different soil layers to T. Results showed that with rising ETref, T firstly increased and then decreased, and with rising RSWC and LAI, T firstly increased and then gradually stabilised, respectively. The modified Jarvis—Stewart model was able to give comparable estimates of T to those derived from sap flow measurements. The contribution of RSWC to T in different soil layers has obvious specificity, and the contribution rate of 20–40 cm (13.4%) and 0–20 cm soil layers (6.6%) where roots are mainly distributed is significantly higher than that of 40–60 cm soil layer (1.9%). As the soil moisture status changes from moist (RSWC0–60cm ≥ 0.4) to drought (RSWC0–60cm < 0.4), the role of the soil moisture in the 0–20 cm soil layer increased compared with other layers. The impacts of soil moisture that were coupled into the Jarvis—Stewart model can genuinely reflect the environmental influence and can be used to quantify the contributions of soil moisture to T. Thus, it has the potential to become a new tool to guide the protection and management of forest water resources.

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Soil pH and Organic Carbon Properties Drive Soil Bacterial Communities in Surface and Deep Layers Along an Elevational Gradient

Frontiers in Microbiology ◽

10.3389/fmicb.2021.646124 ◽

2021 ◽

Vol 12 ◽

Author(s):

Qiuxiang Tian ◽

Ying Jiang ◽

Yanan Tang ◽

Yu Wu ◽

Zhiyao Tang ◽

...

Keyword(s):

Community Composition ◽

Bacterial Communities ◽

Bacterial Community Composition ◽

Soil Layer ◽

Elevational Gradient ◽

Deep Soil ◽

Soil Layers ◽

Soil C ◽

Soil Bacterial Communities ◽

Soil Bacterial

Elevational gradients strongly affect the spatial distribution and structure of soil bacterial communities. However, our understanding of the effects and determining factors is still limited, especially in the deep soil layer. Here, we investigated the diversity and composition of soil bacterial communities in different soil layers along a 1,500-m elevational gradient in the Taibai Mountain. The variables associated with climate conditions, plant communities, and soil properties were analyzed to assess their contributions to the variations in bacterial communities. Soil bacterial richness and α-diversity showed a hump-shaped trend with elevation in both surface and deep layers. In the surface layer, pH was the main factor driving the elevational pattern in bacterial diversity, while in the deep layer, pH and soil carbon (C) availability were the two main predictors. Bacterial community composition differed significantly along the elevational gradient in all soil layers. In the surface layer, Acidobacteria, Delta-proteobacteria, and Planctomycetes were significantly more abundant in the lower elevation sites than in the higher elevation sites; and Gemmatimonadetes, Chloroflexi, and Beta-proteobacteria were more abundant in the higher elevation sites. In the deep layer, AD3 was most abundant in the highest elevation site. The elevational pattern of community composition co-varied with mean annual temperature, mean annual precipitation, diversity and basal area of trees, pH, soil C availability, and soil C fractions. Statistical results showed that pH was the main driver of the elevational pattern of the bacterial community composition in the surface soil layer, while soil C fractions contributed more to the variance of the bacterial composition in the deep soil layer. These results indicated that changes in soil bacterial communities along the elevational gradient were driven by soil properties in both surface and deep soil layers, which are critical for predicting ecosystem functions under future climate change scenarios.

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SOIL C AND N AS INDICATORS OF VINEYARD SOIL QUALITY IN THE RAVNI KOTARI REGION OF CROATIA

10.1130/abs/2020se-345231 ◽

2020 ◽

Author(s):

Sonia C. Clemens ◽

◽

Mia Brkljaca ◽

Delaina Pearson ◽

C. Brannon Andersen

Keyword(s):

Soil Quality ◽

Soil C ◽

Vineyard Soil ◽

Soil C And N ◽

C And N

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Spatially Related Sampling Uncertainty in the Assessment of Labile Soil Carbon and Nitrogen in an Irish Forest Plantation

Applied Sciences ◽

10.3390/app11052139 ◽

2021 ◽

Vol 11 (5) ◽

pp. 2139

Author(s):

Junliang Zou ◽

Bruce Osborne

Keyword(s):

Spatial Variability ◽

Soil Carbon ◽

Sampling Effort ◽

Limited Information ◽

Sampling Area ◽

Soil C ◽

Distribution Maps ◽

Soil C And N ◽

C And N ◽

Highly Correlated

The importance of labile soil carbon (C) and nitrogen (N) in soil biogeochemical processes is now well recognized. However, the quantification of labile soil C and N in soils and the assessment of their contribution to ecosystem C and N budgets is often constrained by limited information on spatial variability. To address this, we examined spatial variability in dissolved organic carbon (DOC) and dissolved total nitrogen (DTN) in a Sitka spruce forest in central Ireland. The results showed moderate variations in the concentrations of DOC and DTN based on the mean, minimum, and maximum, as well as the coefficients of variation. Residual values of DOC and DTN were shown to have moderate spatial autocorrelations, and the nugget sill ratios were 0.09% and 0.10%, respectively. Distribution maps revealed that both DOC and DTN concentrations in the study area decreased from the southeast. The variability of both DOC and DTN increased as the sampling area expanded and could be well parameterized as a power function of the sampling area. The cokriging technique performed better than the ordinary kriging for predictions of DOC and DTN, which are highly correlated. This study provides a statistically based assessment of spatial variations in DOC and DTN and identifies the sampling effort required for their accurate quantification, leading to improved assessments of forest ecosystem C and N budgets.

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