scholarly journals Density-Based Soil Organic Carbon Fractionation: Experimental Method Comparison and Influential Factors

2021 ◽  
Author(s):  
Xiaolu Sun ◽  
Michael G. Ryan ◽  
Osbert Jianxin Sun ◽  
Zuoxin Tang
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Experimental Method ◽  
Soil Type ◽  
Vegetation Type ◽  
Clay Content ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Climate Condition ◽  
Soc Fractions

Abstract Background: Because soil organic carbon (SOC) variation is a result of its physicochemical protection, fractionating SOC into different functional subpools according to its protection mechanism and studying the mechanism of different SOC fractions’ responses to environmental change will help guide the study of SOC dynamics. Therefore, we conducted an analysis of density-based SOC fractionation of 107 study sites from 35 literature sources to answer the following questions: (1) Will different fractionation methods yield different amounts in the three organic carbon pools: free organic carbon (FOC), occluded organic carbon (OOC) and mineral associated organic carbon (MOC)? (2) Does the distribution of these three SOC fractions differ with climate (mean annual temperature, MAT; mean annual precipitation, MAP), soil characteristics (e.g., soil layer, soil type, clay content) or vegetation type when controlling for any method differences?Results: Experimental method significantly affected OOC and MOC but not FOC results, and OOC separated by density and soil physical dispersion (density+disperse) was underestimated, thus a suitable SOC fractionation method should be carefully selected. SOC and MOC contents were negatively related to MAT; and highest SOC content appeared at moderate MAP, and when MAP increased or decreased, SOC decreased. SOC, FOC, and MOC were significantly affected by vegetation type; presumably due to anthropogenic disturbance or precipitation, plantations, grass and rainforest had the lower SOC contents and higher OOC and MOC percentages; and conifer, broadleaf, and mixed forests had similar FOC, OOC and MOC percentages, indicating less effect of tree species on SOC variation. The contents of both SOC and each fraction decreased in deeper sol layer; SOC, FOC and OOC contents were significantly affected by soil type; and SOC and MOC contents were negatively related to soil clay content, but the influences of soil characters on SOC and its fractions were less than experimental method and climate condition.Conclusion: Experimental methods for fractionation of SOC significantly affected fraction results. Climate, vegetation type and soil character also significantly influenced SOC and its factions, but the influences of soil characters on SOC and its fractions were not as strong as experimental method and climate condition.

scholarly journals Temperature exerted no influence on the organic carbon isotope of surface soil along the isopleth of 400 mm mean annual precipitation in China

2016 ◽  
Author(s):  
Yufu Jia ◽  
Guoan Wang ◽  
Zixun Chen
Keyword(s):  
Environmental Factors ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Isotope ◽  
Soil Type ◽  
Surface Soil ◽  
Vegetation Type ◽  
Effect Of Temperature ◽  
Mean Annual Precipitation ◽  
Organic Carbon Isotope

Abstract. Soil organic carbon is the largest pool of terrestrial ecosystem and its carbon isotope composition is affected by many factors. However, the influence of environmental factors, especially temperature, on soil organic carbon isotope (δ13CSOM) is poorly constrained. This impedes interpretations and application of variability of organic carbon isotope in reconstructions of paleoclimate and paleoecology and global carbon cycling. With a considerable temperature gradient along the 400 mm isohyet (isopleth of mean annual precipitation – MAP) in China, this isohyet provides ideal experimental sites for studying the influence of temperature on soil organic carbon isotope. In this study, the effect of temperature on surface soil δ13C was assessed by a comprehensive investigation from 27 sites across a temperature gradient along the isohyet. This work demonstrates that temperature did not play a role in soil δ13C, this suggests that organic carbon isotopes in sediments cannot be used for the paleotemperature reconstruction, and that the effect of temperature on organic carbon isotopes can be neglected in the reconstruction of paleoclimate and paleovegetation. Multiple regression with MAT (mean annual temperature), MAP, altitude, latitude and longitude as independent variables, and δ13CSOM as the dependent variable, shows that the five environmental factors in total account for only 9 % soil δ13C variance. However, One-way ANOVA analyses suggest that soil and vegetation types are significant influential factors on soil δ13C. Multiple regressions in which above five environmental factors were taken as quantitative variables, vegetation type, Chinese nomenclature soil type and WRB soil type were introduced as dummy variables separately, show that 36.2 %, 37.4 %, 29.7 % of the variability in soil δ13C are explained, respectively. Compared to the multiple regression in which only quantitative environmental variables were introduced, the multiple regressions in which soil and vegetation were also introduced explain more variance, suggesting that soil type and vegetation type really exerted significant influences on δ13CSOM.

scholarly journals Temperature exerts no influence on organic matter <i>δ</i><sup>13</sup>C of surface soil along the 400 mm isopleth of mean annual precipitation in China

2016 ◽  
Vol 13 (17) ◽  
pp. 5057-5064 ◽  
Author(s):  
Yufu Jia ◽  
Guoan Wang ◽  
Qiqi Tan ◽  
Zixun Chen
Keyword(s):  
Environmental Factors ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Isotopes ◽  
Soil Type ◽  
Vegetation Type ◽  
Effect Of Temperature ◽  
Mean Annual Precipitation ◽  
Multiple Regressions ◽  
Organic Carbon Isotopes

Abstract. Soil organic carbon is the largest pool of carbon in the terrestrial ecosystem, and its isotopic composition is affected by a number of factors. However, the influence of environmental factors, especially temperature, on soil organic carbon isotope values (δ13CSOM) is poorly constrained. This impedes the application of the variability of organic carbon isotopes to reconstructions of paleoclimate, paleoecology, and global carbon cycling. Given the considerable temperature gradient along the 400 mm isohyet (isopleth of mean annual precipitation – MAP) in China, this isohyet provides ideal experimental sites for studying the influence of temperature on soil organic carbon isotopes. In this study, the effect of temperature on surface soil δ13C was assessed by a comprehensive investigation of 27 sites across a temperature gradient along the isohyet. Results demonstrate that temperature does not play a role in soil δ13C. This suggests that organic carbon isotopes in sediments cannot be used for paleotemperature reconstruction and that the effect of temperature on organic carbon isotopes can be neglected in the reconstruction of paleoclimate and paleovegetation. Multiple regressions with MAT (mean annual temperature), MAP, altitude, latitude, and longitude as independent variables and δ13CSOM as the dependent variable show that these five environmental factors together account for only 9 % of soil δ13C variance. However, one-way ANOVA analyses suggest that soil type and vegetation type are significant factors influencing soil δ13C. Multiple regressions, in which the five aforementioned environmental factors were taken as quantitative variables, and vegetation type, soil type based on the Chinese Soil Taxonomy, and World Reference Base (WRB) soil type were separately used as dummy variables, show that 36.2, 37.4, and 29.7 %, respectively, of the variability in soil δ13C are explained. Compared to the multiple regressions in which only quantitative environmental variables were introduced, the multiple regressions in which soil and vegetation were also introduced explain more of the isotopic variance, suggesting that soil type and vegetation type exert a significant influence on δ13CSOM.

scholarly journals Large-scale controls of soil organic carbon in (sub)tropical soils

2020 ◽  
Author(s):  
Sophie F. von Fromm ◽  
Alison M. Hoyt ◽  
Asmeret Asefaw Berhe ◽  
Keith D. Shepherd ◽  
Tor-Gunnar Vågen ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Large Scale ◽  
Experimental Studies ◽  
Clay Content ◽  
Carbon Stocks ◽  
Sub Saharan Africa ◽  
Mean Annual Precipitation ◽  
Tropical Regions ◽  
Continental Scale

&lt;p&gt;Soil organic carbon (SOC) is a key component of terrestrial ecosystems. Experimental studies have shown that soil texture and geochemistry have a strong effect on carbon stocks. However, those findings primarily rely on data from temperate regions or use model approaches that are often based on limited data from tropical and sub-tropical regions.&lt;/p&gt;&lt;p&gt;Here, we evaluate the controls on soil carbon stocks in Africa, using a dataset of 1,580 samples. These were collected across Sub-Saharan Africa (SSA) within the framework of the Africa Soil Information Service (AfSIS) project, which was built on the well-established Land Degradation Surveillance Framework (LDSF). Samples were taken from two depths (0&amp;#8211;20 cm and 20&amp;#8211;50 cm) at 46 LDSF sites that were stratified according to Koeppen-Geiger climate zones. The different pH-values, clay content, exchangeable cations and extractable elements across various soils of the different climatic zones (i.e. from arid to humid (sub)tropical) allow us to identify different soil and climate parameters that best explain SOC variance across SSA.&lt;/p&gt;&lt;p&gt;We tested if these SOC predictors differed across climatological conditions, using the ratio of potential evapotranspiration (PET) to mean annual precipitation (MAP) as indicator. For water-limited regions (PET/MAP &gt; 1), the best predictors were climatic variables, likely because of their effect on the quantity of carbon inputs. Geochemistry dominated SOC storage in energy-limited systems (PET/MAP &lt; 1), reflecting its effect on carbon protection. On a continental scale, climate (e.g. PET) is key to predicting SOC content in topsoil, whereas geochemistry, particularly iron-oxyhydroxides and aluminum-oxides, is more important in subsoil. Clay content had little influence on SOC at both depths. These findings contribute to an improved understanding of the controls on SOC stocks in tropical and sub-tropical regions.&lt;/p&gt;

scholarly journals Stable isotopic constraints on global soil organic carbon turnover

2018 ◽  
Vol 15 (4) ◽  
pp. 987-995 ◽  
Author(s):  
Chao Wang ◽  
Benjamin Z. Houlton ◽  
Dongwei Liu ◽  
Jianfeng Hou ◽  
Weixin Cheng ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Linear Relationship ◽  
Root Decomposition ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Turnover Rates ◽  
Decomposition Rates ◽  
Soil C ◽  
C Stocks

Abstract. Carbon dioxide release during soil organic carbon (SOC) turnover is a pivotal component of atmospheric CO2 concentrations and global climate change. However, reliably measuring SOC turnover rates on large spatial and temporal scales remains challenging. Here we use a natural carbon isotope approach, defined as beta (β), which was quantified from the δ13C of vegetation and soil reported in the literature (176 separate soil profiles), to examine large-scale controls of climate, soil physical properties and nutrients over patterns of SOC turnover across terrestrial biomes worldwide. We report a significant relationship between β and calculated soil C turnover rates (k), which were estimated by dividing soil heterotrophic respiration rates by SOC pools. ln( − β) exhibits a significant linear relationship with mean annual temperature, but a more complex polynomial relationship with mean annual precipitation, implying strong-feedbacks of SOC turnover to climate changes. Soil nitrogen (N) and clay content correlate strongly and positively with ln( − β), revealing the additional influence of nutrients and physical soil properties on SOC decomposition rates. Furthermore, a strong (R2 = 0.76; p < 0.001) linear relationship between ln( − β) and estimates of litter and root decomposition rates suggests similar controls over rates of organic matter decay among the generalized soil C stocks. Overall, these findings demonstrate the utility of soil δ13C for independently benchmarking global models of soil C turnover and thereby improving predictions of multiple global change influences over terrestrial C-climate feedback.

scholarly journals Stable isotopic constraints on global soil organic carbon turnover

2017 ◽  
Author(s):  
Chao Wang ◽  
Benjamin Z. Houlton ◽  
Dongwei Liu ◽  
Jianfeng Hou ◽  
Weixin Cheng ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Large Scale ◽  
Global Climate ◽  
Mean Annual Precipitation ◽  
Complex Polynomial ◽  
Mean Annual Temperature ◽  
Turnover Rates ◽  
Soil C ◽  
Spatial And Temporal Scales

Abstract. Carbon dioxide release during soil organic carbon (SOC) turnover is a pivotal component of atmospheric CO2 concentrations and global climate change. However, reliably measuring SOC turnover rates at large spatial and temporal scales remains challenging. Here we use a natural carbon isotope approach, defined as beta (β), which was quantified from the δ13C of vegetation and soil reported in the literature (182 separate soil profiles), to examine large-scale controls of climate, soil physical properties and nutrients over patterns of SOC turnover across terrestrial biomes worldwide. We report a significant relationship between β and calculated soil C turnover rates (k), which were estimated by dividing soil heterotrophic respiration by SOC pools. ln(-β) exhibits a significant linear relationship with mean annual temperature, but a more complex polynomial relationship with mean annual precipitation, implying strong-feedbacks of SOC turnover to climate changes. Soil nitrogen (N) and clay content correlate strongly and positively with ln(-β), revealing the additional influence of nutrients and physical soil properties on SOC decomposition rates. Furthermore, a strong (R2 = 0.85; p 

scholarly journals Organic mulching promotes soil organic carbon accumulation to deep soil layer in an urban plantation forest

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Xiaodan Sun ◽  
Gang Wang ◽  
Qingxu Ma ◽  
Jiahui Liao ◽  
Dong Wang ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Content ◽  
Fine Roots ◽  
Soil Layer ◽  
Carbon Accumulation ◽  
Bulk Soil ◽  
Organic Mulch ◽  
The Impact ◽  
Soc Fractions

Abstract Background Soil organic carbon (SOC) is important for soil quality and fertility in forest ecosystems. Labile SOC fractions are sensitive to environmental changes, which reflect the impact of short-term internal and external management measures on the soil carbon pool. Organic mulching (OM) alters the soil environment and promotes plant growth. However, little is known about the responses of SOC fractions in rhizosphere or bulk soil to OM in urban forests and its correlation with carbon composition in plants. Methods A one-year field experiment with four treatments (OM at 0, 5, 10, and 20 cm thicknesses) was conducted in a 15-year-old Ligustrum lucidum plantation. Changes in the SOC fractions in the rhizosphere and bulk soil; the carbon content in the plant fine roots, leaves, and organic mulch; and several soil physicochemical properties were measured. The relationships between SOC fractions and the measured variables were analysed. Results The OM treatments had no significant effect on the SOC fractions, except for the dissolved organic carbon (DOC). OM promoted the movement of SOC to deeper soil because of the increased carbon content in fine roots of subsoil. There were significant correlations between DOC and microbial biomass carbon and SOC and easily oxidised organic carbon. The OM had a greater effect on organic carbon fractions in the bulk soil than in the rhizosphere. The thinnest (5 cm) mulching layers showed the most rapid carbon decomposition over time. The time after OM had the greatest effect on the SOC fractions, followed by soil layer. Conclusions The frequent addition of small amounts of organic mulch increased SOC accumulation in the present study. OM is a potential management model to enhance soil organic matter storage for maintaining urban forest productivity.

scholarly journals Influence of trees and associated variables on soil organic carbon: a review

2021 ◽  
Vol 45 (1) ◽  
Author(s):  
Angom Sarjubala Devi
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Significant Negative Correlation ◽  
Mean Annual Temperature ◽  
Forest Stands ◽  
Mixed Stands ◽  
Silt Fraction ◽  
Different Types ◽  
Soil Climate ◽  
Associated Variables

AbstractThe level of soil organic carbon (SOC) fluctuates in different types of forest stands: this variation can be attributed to differences in tree species, and the variables associated with soil, climate, and topographical features. The present review evaluates the level of SOC in different types of forest stands to determine the factors responsible for the observed variation. Mixed stands have the highest amount of SOC, while coniferous (both deciduous-coniferous and evergreen-coniferous) stands have greater SOC concentrations than deciduous (broadleaved) and evergreen (broadleaved) tree stands. There was a significant negative correlation between SOC and mean annual temperature (MAT) and sand composition, in all types of forest stands. In contrast, the silt fraction has a positive correlation with SOC, in all types of tree stands. Variation in SOC under different types of forest stands in different landscapes can be due to differences in MAT, and the sand and silt fraction of soil apart from the type of forests.

Soil organic carbon quality in forested mineral wetlands at different mean annual temperature

2009 ◽  
Vol 41 (3) ◽  
pp. 458-466 ◽  
Author(s):  
Cinzia Fissore ◽  
Christian P. Giardina ◽  
Randall K. Kolka ◽  
Carl C. Trettin
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Mean Annual Temperature ◽  
Carbon Quality

scholarly journals Soil organic carbon in northern Spain (Galicia, Asturias, Cantabria and País Vasco)

2015 ◽  
Vol 5 ◽  
Author(s):  
Elías Luis Calvo ◽  
Francisco Casás Sabarís ◽  
Juan Manuel Galiñanes Costa ◽  
Natividad Matilla Mosquera ◽  
Felipe Macías Vázquez ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Forest Soils ◽  
Agricultural Soils ◽  
Calcareous Soils ◽  
Mean Annual Precipitation ◽  
Moisture Regime ◽  
Organic Carbon Content ◽  
Northern Spain ◽  
Pais Vasco

The soil organic carbon content was analyzed in more than 7 000 soil samples under different land uses, climates and lithologies from northern Spain (Galicia, Asturias, Cantábria y País Vasco). GIS maps (1:50 000) were made of the % SOC and SOC stocks. The % SOC varies according to land use (higher in forest and scrub soils and lower in agricultural soils) and climate, and there is a highly significant correlation between SOC content and mean annual precipitation. There are significant differences between the soils of Galicia/Western Asturias (GA<sub>w</sub>) and those of the rest of the study area (Central and Eastern Asturias, Cantabria and País Vasco) (A<sub>ce</sub>CV), although these are neighbouring regions. In forest and/or scrub soils with a <em>udic</em> soil moisture regime, in GA<sub>w</sub>, the SOC is usually &gt; 7% and the average stocks 260 t ha<sup> -1</sup> (0-30 cm), and &gt;340 t ha<sup>-1</sup> (0-50 cm) in soils with thick organic matter rich horizons (&gt; 40 cm); these values greatly exceed the average contents observed in forest soils from temperate zones. Under similar conditions of vegetation and climate in soils of A<sub>ce</sub>CV the SOC average is 3% and the mean stocks 90-100 t ha<sup>-1</sup> (0-30 cm). The <em>andic</em> character of acid forest soils in GA<sub>w</sub> and the formation of C-Al,Fe complexes are pointed out as the SOC stabilization mechanism, in contrast to the neutral and calcareous soils that predominate in A<sub>ce</sub>CV, where the main species of OC are easily biodegradable.

scholarly journals Soil organic carbon storage in moutain grasslands of the Lake Plateau at Mt. Durmitor in Montenegro

2012 ◽  
pp. 113-128 ◽  
Author(s):  
Ratko Kadovic ◽  
Snezana Belanovic ◽  
Dragica Obratov-Petkovic ◽  
Ivana Bjedov ◽  
Veljko Perovic ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Average Density ◽  
Mean Annual Temperature ◽  
Carbon Density ◽  
Mountain Areas ◽  
Organic C ◽  
C Storage ◽  
Soil Variables ◽  
Soil Organic Carbon Density

Soil organic C storage in mountain areas is highly heterogeneous, mainly as a result of local-scale variability in the soil environment and microclimate. The aims of the present study were to estimate soil organic carbon density (SOCD) and stocks in leptosol on morainic deposits of high-altitude grasslands of the Lake Plateau of Mt. Durmitor National Park in Montenegro, and determine the soil variables that can be used as factors to determine the SOCD at 28 soil profiles. Our results indicated that SOC storage in the top 40 cm of the alpine grasslands were estimated at 560 414.86 t C, or 152.66 t?ha-1, with an average density of 15.27 kg?m-2. The soil organic carbon density increased significantly with soil moisture, clay and silt content, but only moderately with mean annual temperature. In conjunction, these variables could explain approximately 51% of the total variation in SOC density.

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