Differences in pedotransfer functions of bulk density lead to high uncertainty in soil organic carbon estimation at regional scales: Evidence from Chinese terrestrial ecosystems

Xu, Lin; He, Nianpeng; Yu, Guirui; Wen, Ding; Gao, Yang; He, Honglin

doi:10.1002/2015jg002929

Cited by 32 publications

(25 citation statements)

References 45 publications

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“…As a basic physical property of soil, BD not only affects the availability of soil moisture and nutrients, but also indirectly reflects soil quality and productivity (Reichert et al, 2009;Sequeira et al, 2014). Furthermore, BD is one of the most important parameters used to calculate soil organic carbon (SOC) storage; and the differences in the selected methods used to substitute for missing BD have been considered one of the main reasons for high uncertainty in SOC storage estimates at a regional scale (Benites et al, 2007;Dawson and Smith, 2007;Wiesmeier et al, 2012;Xu et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…While these substitution methods allow us to estimate SOC storage at regional or global scales, they also introduce uncertainty into the results. For example, using the same data source (Second National Soil Survey in China; SNSSC), the estimated values of SOC storage have ranged from 7.8 to 10.3 kg C m −2 in Chinese terrestrial ecosystems under different BD substitution approaches (Wang et al, 2004;Xie et al, 2007;Yang et al, 2007;Yu et al, 2007;Xu et al, 2015). A number of studies that focused on the influence of BD on SOC storage estimations have emphasized the importance of optimizing PTFs (De Vos et al, 2005;Wiesmeier et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Methods of evaluating soil bulk density: Impact on estimating large scale soil organic carbon storage

2016

CATENA

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Bulk density (BD) is one of the most important parameters used to calculate soil organic carbon (SOC) storage. Differences in the methods available to substitute missing BD data, including mean, median, and pedo-transfer functions (PTFs), are considered the main reason for the high uncertainty in SOC storage estimations at large scales. In this study, we used the measured BD and SOC contents of 1007 soil profiles to evaluate the accuracy of six BD substitution methods (two mean methods, a median method, and three PTFs). The results showed that PTFs underestimated SOC storage by 8% in the 0-20 cm soil layer, while mean and median methods overestimated SOC storage by 45% and 51%, respectively. Furthermore, the accuracy of PTFs estimates decreased with increasing soil depth. Relative to the measured values, and based on mean errors, root mean square errors, and method efficiency, the PFTs estimates were more accurate than those of the mean and median methods. Estimation bias increased with increasing SOC content for all methods, but differed among different soil types. The results of this study demonstrate that PTFs provide more accurate estimates of SOC storage when the extent of missing BD is substantial. Furthermore, the results provide new insights into establishing optimized PTFs, which contain more soil properties and piecewise functions of SOC content, in order to improve SOC storage estimates at large scales.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Methods of evaluating soil bulk density: Impact on estimating large scale soil organic carbon storage

2016

CATENA

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“…With respect to the SOC stocks at the 0-20 cm depth, our estimation (4.89 kg m -2 for alpine meadow and 2.61 kg m -2 for alpine steppe) is lower than the one of Yang et al (2010) (6.23 kg m -2 for alpine meadow and 3.00 kg m -2 for alpine steppe) and Chang et al (2014) (5.37 kg m -2 for alpine meadow and 3.28 kg m -2 for alpine steppe). In this study, the bulk density for the calculation of the SOC stocks were obtained by using pedotransfer functions (Xu et al 2015), which may explain the difference. Furthermore, the difference could also be due to the underrepresentation of sampling sites in our present study, which would increase the uncertainty in regional SOC stock estimation (Chang et al 2014).…”

Section: Soc and Its Fractionsmentioning

confidence: 99%

“…In the present study, soil bulk density was mean values obtained from eight common pedo-transfer functions (Xu et al 2015). Mean weight diameter (MWD), geometric mean diameter (GMD), percentage of > 0.25 mm water stable aggregates (R 0.25 ), structure deterioration rate (SDR), index of unstable aggregates (E LT ), and stability ratio of water stable aggregate (WSAR) were calculated according to the methods described by Fan et al (2010), Gupta Choudhury et al (2014), and Liu et al (2014a).…”

Section: Calculations and Statistical Analysismentioning

confidence: 99%

Soil organic carbon contents, aggregate stability, and humic acid composition in different alpine grasslands in Qinghai-Tibet Plateau

Cao

Yong

et al. 2016

J. Mt. Sci.

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Alpine grassland soils on Qinghai-Tibet Plateau store approximately 33.5 Pg of organic carbon (C) at 0-0.75 m depth and play an important role in the global carbon cycle. We investigated soil organic C (SOC), water-soluble organic C (WSOC), easily oxidizable organic C (EOC), humic C fractions, aggregate-associated C, aggregate stability, and humic acid (HA) composition along an east-west transect across Qinghai-Tibet Plateau, and explored their spatial patterns and controlling factors. The contents of SOC, WSOC, EOC, humic C fractions and aggregate-associated C, the proportions of macroaggregates (2-0.25) and micro-aggregates (0.25-0.053 mm), and the aggregate stability indices all increased in the order alpine desert < alpine steppe < alpine meadow. The alkyl C, O-alkyl C, and aliphatic C/aromatic C ratio of HA increased as alpine desert < alpine meadow < alpine steppe, and the trends were reverse for the aromatic C and HB/HI ratio. Mean annual precipitation and aboveground biomass were significantly correlated with the contents of SOC and its fractions, the proportions of macro-and microaggregates, and the aggregate stability indices along this transect. Among all these C fractions, SOC content and aggregate stability were more closely associated with humic C and silt and clay sized C in comparison with WSOC, EOC, and macro-and microaggregate C. The results suggested that alpine meadow soils containing higher SOC exhibited high soil aggregation and aggregate stability. Mean annual precipitation should be the main climate factor controlling the spatial patterns of SOC, soil aggregation, and aggregate stability in this region. The resistant and stable C fractions rather than labile C fractions are the major determinant of SOC stocks and aggregate stability. Keywords

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“…The main reason for high uncertainty of soil organic carbon stock results from the difference in bulk density methods (Dawson and Smith, 2007;Xu et al, 2015). It is described as the weight of dry soil for a given volume.…”

Section: Introductionmentioning

confidence: 99%

Comparison of bulk density methods in determining soil organic carbon storage under different land use types

Gebre¹

2018

J. Soil Sci. Environ. Manage.

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The different methods used for determining soil bulk density make the result of soil organic carbon (SOC) estimation vary. The study was conducted on five land use types in Gergera watershed, Tigray, Ethiopia. This study investigates two methods (Core and Excavation methods) of soil bulk density and their relative consequence on SOC; it also evaluates which method is better for estimating SOC stock. Both methods were undertaken in top 0 to 30 cm soil depth. For comparison of bulk density methods, statistical package for social science (SPSS) version 23 was used. The result revealed that using core method, SOC was 59.30, 74.70, 64.18, 45.35 and 54.61 Mg/ha in pasture land, homestead agroforestry, crop land and woodlot respectively. Whereas, land use types were scored 56.40, 69.08, 62.20, 43.86 and 52.83 Mg/ha in exclosure, pasture land, homestead agroforestry, crop land and woodlot respectively using excavation method of bulk density determination. Although SOC stock exhibits statistically significant difference among land use types in the bulk density methods, the statistical effect was not because of bulk density methods but because of other variables in the land use types. SOC of bulk density results and mean SOC difference in each land use types were calculated using core and excavation methods. In conclusion, soil excavation method of bulk density determinations used for SOC estimation is the lower standard error. Furthermore, this work provides new insights into improving the bulk density methods and assists in the accurate estimation of soil carbon stock management.

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Differences in pedotransfer functions of bulk density lead to high uncertainty in soil organic carbon estimation at regional scales: Evidence from Chinese terrestrial ecosystems

Cited by 32 publications

References 45 publications

Methods of evaluating soil bulk density: Impact on estimating large scale soil organic carbon storage

Methods of evaluating soil bulk density: Impact on estimating large scale soil organic carbon storage

Soil organic carbon contents, aggregate stability, and humic acid composition in different alpine grasslands in Qinghai-Tibet Plateau

Comparison of bulk density methods in determining soil organic carbon storage under different land use types

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