Sampling probes affect bulk density and soil organic carbon measurements

Abstract. Estimation of soil organic carbon (SOC) stocks requires estimates of the carbon content, bulk density, stone content and depth of a respective soil layer. However, different application of these parameters could introduce a considerable bias. Here, we explain why three out of four frequently applied methods overestimate SOC stocks. In stone rich soils (> 30 Vol. %), SOC stocks could be overestimated by more than 100 %, as revealed by using German Agricultural Soil Inventory data. Due to relatively low stone content, the mean systematic overestimation for German agricultural soils was 2.1–10.1 % for three different commonly used equations. The equation ensemble as re-formulated here might help to unify SOC stock determination and avoid overestimation in future studies.

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Organic carbon partitioning in soil and litter in subtropical woodlands and open forests: a case study from the Brigalow Belt, Queensland

The Rangeland Journal ◽

10.1071/rj05015 ◽

2006 ◽

Vol 28 (2) ◽

pp. 115 ◽

Cited By ~ 12

Author(s):

S. H. Roxburgh ◽

B. G. Mackey ◽

C. Dean ◽

L. Randall ◽

A. Lee ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Carbon ◽

Bulk Density ◽

Soil Surface ◽

Soil Bulk Density ◽

Carbon Stocks ◽

Soil Carbon Stocks ◽

Landscape Scales ◽

Open Forests

A woodland–open forest landscape within the Brigalow Belt South bioregion of Queensland, Australia, was surveyed for soil organic carbon, soil bulk density and soil-surface fine-litter carbon. Soil carbon stocks to 30 cm depth across 14 sites, spanning a range of soil and vegetation complexes, ranged from 10.7 to 61.8 t C/ha, with an overall mean of 36.2 t C/ha. Soil carbon stocks to 100 cm depth ranged from 19.4 to 150.5 t C/ha, with an overall mean of 72.9 t C/ha. The standing stock of fine litter ranged from 1.0 to 7.0 t C/ha, with a mean of 2.6 t C/ha, and soil bulk density averaged 1.4 g/cm3 at the soil surface, and 1.6 g/cm3 at 1 m depth. These results contribute to the currently sparse database of soil organic carbon and bulk density measurements in uncultivated soils within Australian open forests and woodlands. The estimates of total soil organic carbon stock calculated to 30 cm depth were further partitioned into resistant plant material (RPM), humus (HUM), and inert organic matter (IOM) pools using diffuse mid-infrared (MIR) analysis. Prediction of the HUM and RPM pools using the RothC soil carbon model agreed well with the MIR measurements, confirming the suitability of RothC for modelling soil organic carbon in these soils. Methods for quantifying soil organic carbon at landscape scales were also explored, and a new regression-based technique for estimating soil carbon stocks from simple field-measured soil attributes has been proposed. The results of this study are discussed with particular reference to the difficulties encountered in the collection of the data, their limitations, and opportunities for the further development of methods for quantifying soil organic carbon at landscape scales.

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Land use and management influences on surface soil organic carbon in Tasmania

Soil Research ◽

10.1071/sr12251 ◽

2013 ◽

Vol 51 (8) ◽

pp. 615 ◽

Cited By ~ 15

Author(s):

W. E. Cotching ◽

G. Oliver ◽

M. Downie ◽

R. Corkrey ◽

R. B. Doyle

Keyword(s):

Land Use ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Carbon ◽

Bulk Density ◽

Management Practices ◽

Carbon Stocks ◽

Carbon Accounting ◽

Continuous Cropping ◽

Texture Contrast

The effects of environmental parameters, land-use history, and management practices on soil organic carbon (SOC) concentrations, nitrogen, and bulk density were determined in agricultural soils of four soil types in Tasmania. The sites sampled were Dermosols, Vertosols, Ferrosols, and a group of texture-contrast soils (Chromosol and Sodosol) each with a 10-year management history ranging from permanent perennial pasture to continuous cropping. Rainfall, Soil Order, and land use were all strong explanatory variables for differences in SOC, soil carbon stock, total nitrogen, and bulk density. Cropping sites had 29–35% less SOC in surface soils (0–0.1 m) than pasture sites as well as greater bulk densities. Clay-rich soils contained the greatest carbon stocks to 0.3 m depth under pasture, with Ferrosols containing a mean of 158 Mg C ha–1, Vertosols 112 Mg C ha–1, and Dermosols 107 Mg C ha–1. Texture-contrast soils with sandier textured topsoils under pasture had a mean of 69 Mg C ha–1. The range of values in soil carbon stocks indicates considerable uncertainty in baseline values for use in soil carbon accounting. Farmers can influence SOC more by their choice of land use than their day-to-day soil management. Although the influence of management is not as great as other inherent site variables, farmers can still select practices for their ability to retain more SOC.

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Incorporation of globally available datasets into the roving cosmic-ray neutron probe method for estimating field-scale soil water content

Hydrology and Earth System Sciences ◽

10.5194/hess-20-3859-2016 ◽

2016 ◽

Vol 20 (9) ◽

pp. 3859-3872 ◽

Cited By ~ 27

Author(s):

William Alexander Avery ◽

Catherine Finkenbiner ◽

Trenton E. Franz ◽

Tiejun Wang ◽

Anthony L. Nguy-Robertson ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Water Content ◽

Bulk Density ◽

Soil Water Content ◽

Cosmic Ray ◽

Soil Bulk Density ◽

Local Soil ◽

Calibration Parameters

Abstract. The need for accurate, real-time, reliable, and multi-scale soil water content (SWC) monitoring is critical for a multitude of scientific disciplines trying to understand and predict the Earth's terrestrial energy, water, and nutrient cycles. One promising technique to help meet this demand is fixed and roving cosmic-ray neutron probes (CRNPs). However, the relationship between observed low-energy neutrons and SWC is affected by local soil and vegetation calibration parameters. This effect may be accounted for by a calibration equation based on local soil type and the amount of vegetation. However, determining the calibration parameters for this equation is labor- and time-intensive, thus limiting the full potential of the roving CRNP in large surveys and long transects, or its use in novel environments. In this work, our objective is to develop and test the accuracy of globally available datasets (clay weight percent, soil bulk density, and soil organic carbon) to support the operability of the roving CRNP. Here, we develop a 1 km product of soil lattice water over the continental United States (CONUS) using a database of in situ calibration samples and globally available soil taxonomy and soil texture data. We then test the accuracy of the global dataset in the CONUS using comparisons from 61 in situ samples of clay percent (RMSE  =  5.45 wt %, R2  =  0.68), soil bulk density (RMSE  =  0.173 g cm−3, R2  =  0.203), and soil organic carbon (RMSE  =  1.47 wt %, R2  =  0.175). Next, we conduct an uncertainty analysis of the global soil calibration parameters using a Monte Carlo error propagation analysis (maximum RMSE ∼  0.035 cm3 cm−3 at a SWC  =  0.40 cm3 cm−3). In terms of vegetation, fast-growing crops (i.e., maize and soybeans), grasslands, and forests contribute to the CRNP signal primarily through the water within their biomass and this signal must be accounted for accurate estimation of SWC. We estimated the biomass water signal by using a vegetation index derived from MODIS imagery as a proxy for standing wet biomass (RMSE  <  1 kg m−2). Lastly, we make recommendations on the design and validation of future roving CRNP experiments.

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Effect of in-situ Incorporation Green Manures on Soil Organic Carbon, pH, Bulk Density and Economics Involved in Its Incorporation

International Journal of Current Microbiology and Applied Sciences ◽

10.20546/ijcmas.2018.709.008 ◽

2018 ◽

Vol 7 (09) ◽

pp. 62-67

Author(s):

Ghous Ali ◽

Ch. Pulla Rao ◽

A.S. Rao ◽

Y. Ashoka Rani

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Bulk Density ◽

Green Manures

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Soils under Shorea robusta in foot hills of the Eastern Himalaya - their characteristics and carbon sequestration potential

Indian Journal of Forestry ◽

10.54207/bsmps1000-2021-56p692 ◽

2020 ◽

Vol 43 (4) ◽

pp. 295-301

Author(s):

Samar Gangopadhyay ◽

◽

Samar Banerjee ◽

Avinash Jain ◽

Saikat Banerjee ◽

...

Keyword(s):

Organic Matter ◽

Carbon Sequestration ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Bulk Density ◽

Clay Content ◽

Carbon Sequestration Potential ◽

Shorea Robusta ◽

Sequestration Potential ◽

Study Sites

Forest soils supporting Sal-Shorea robusta (Roxb. ex Gaertn. f.) plantations in the foot hills of Darjeeling and Kurseong Divisions in West Bengal were studied for their physicochemical characteristics and carbon sequestration potential. Soils are acidic, high in organic carbon and clay content but low in soil reaction (pH) and bulk density (BD). Thick deposit of leaf litter and its decomposition products increase the soil organic carbon (SOC). Significant amount of clay content also increases the moisture content which helps in decomposing the organic matter, reducing the bulk density of soil and reduces erosion. Soil organic matter tends to concentrate with roughly more than half of the soil organic carbon in the upper soil horizons (0-30cm) at all the study sites. Among the study sites, Samardanga block registers lowest SOC while Bamanpukuri block shows highest SOC stock.

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Soil organic carbon stocks are systematically overestimated by misuse of the parameters bulk density and rock fragment content

SOIL ◽

10.5194/soil-3-61-2017 ◽

2017 ◽

Vol 3 (1) ◽

pp. 61-66 ◽

Cited By ~ 51

Author(s):

Christopher Poeplau ◽

Cora Vos ◽

Axel Don

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Bulk Density ◽

Agricultural Soils ◽

Soil Layer ◽

Rock Fragment ◽

Rock Fragments ◽

Soil Organic Carbon Stocks ◽

Soc Stocks ◽

Rock Fragment Content

Abstract. Estimation of soil organic carbon (SOC) stocks requires estimates of the carbon content, bulk density, rock fragment content and depth of a respective soil layer. However, different application of these parameters could introduce a considerable bias. Here, we explain why three out of four frequently applied methods overestimate SOC stocks. In soils rich in rock fragments (> 30 vol. %), SOC stocks could be overestimated by more than 100 %, as revealed by using German Agricultural Soil Inventory data. Due to relatively low rock fragments content, the mean systematic overestimation for German agricultural soils was 2.1–10.1 % for three different commonly used equations. The equation ensemble as re-formulated here might help to unify SOC stock determination and avoid overestimation in future studies.

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Global distribution of soil organic carbon – Part 1: Masses and frequency distributions of SOC stocks for the tropics, permafrost regions, wetlands, and the world

SOIL ◽

10.5194/soil-1-351-2015 ◽

2015 ◽

Vol 1 (1) ◽

pp. 351-365 ◽

Cited By ~ 138

Author(s):

M. Köchy ◽

R. Hiederer ◽

A. Freibauer

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Carbon ◽

Bulk Density ◽

Tropical Soils ◽

Frequency Distributions ◽

Tropical Regions ◽

The World ◽

Global Soil ◽

Soc Stocks

Abstract. The global soil organic carbon (SOC) mass is relevant for the carbon cycle budget and thus atmospheric carbon concentrations. We review current estimates of SOC stocks and mass (stock × area) in wetlands, permafrost and tropical regions and the world in the upper 1 m of soil. The Harmonized World Soil Database (HWSD) v.1.2 provides one of the most recent and coherent global data sets of SOC, giving a total mass of 2476 Pg when using the original values for bulk density. Adjusting the HWSD's bulk density (BD) of soil high in organic carbon results in a mass of 1230 Pg, and additionally setting the BD of Histosols to 0.1 g cm−3 (typical of peat soils), results in a mass of 1062 Pg. The uncertainty in BD of Histosols alone introduces a range of −56 to +180 Pg C into the estimate of global SOC mass in the top 1 m, larger than estimates of global soil respiration. We report the spatial distribution of SOC stocks per 0.5 arcminutes; the areal masses of SOC; and the quantiles of SOC stocks by continents, wetland types, and permafrost types. Depending on the definition of "wetland", wetland soils contain between 82 and 158 Pg SOC. With more detailed estimates for permafrost from the Northern Circumpolar Soil Carbon Database (496 Pg SOC) and tropical peatland carbon incorporated, global soils contain 1325 Pg SOC in the upper 1 m, including 421 Pg in tropical soils, whereof 40 Pg occurs in tropical wetlands. Global SOC amounts to just under 3000 Pg when estimates for deeper soil layers are included. Variability in estimates is due to variation in definitions of soil units, differences in soil property databases, scarcity of information about soil carbon at depths > 1 m in peatlands, and variation in definitions of "peatland".

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Yield and nitrogen use efficiency in wheat, and soil fertility status as influenced by substitution of rice with pigeon pea in a rice - wheat cropping system

Australian Journal of Experimental Agriculture ◽

10.1071/ea04046 ◽

2006 ◽

Vol 46 (9) ◽

pp. 1185 ◽

Cited By ~ 13

Author(s):

V. K. Singh ◽

B. S. Dwivedi

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Bulk Density ◽

Nitrogen Use Efficiency ◽

Soil Profile ◽

Soil Depth ◽

Pigeon Pea ◽

Grain Legume ◽

Nitrogen Use ◽

Use Efficiency

Rice–wheat cropping systems managed on 10 million ha in the Indo-Gangetic Plain region (IGPR) of India are the most important production systems for national food security. Recent reports, however, indicate that the system is under production fatigue and the growth rates of rice and wheat have started declining. We, therefore, conducted field experiments at Modipuram, Meerut, India, for 3 consecutive years (1998–99 to 2000–01), to study the conservation of soil organic carbon, improvement in nitrogen use efficiency and increase in system yields through inclusion of a grain legume (pigeon pea) in place of rice. The wheat yields following pigeon pea crops were significantly (P<0.05) greater than those following rice crops during 1999–2000 and 2000–01, but not during 1998–99. The economic optimum doses of fertiliser N for wheat in the pigeon pea–wheat system were smaller (128–133 kg N/ha) than those in the rice–wheat system (139–173 kg N/ha), owing to increased N supply, greater N use efficiencies and a better crop growth environment in the pigeon pea–wheat system. The post-wheat harvest nitrate-N (NO3-N) at 90–105 cm soil depth in plots fertilised with 120 or 180 kg N/ha was greater for the rice–wheat system (6.5–8.1 mg/kg) than for the pigeon pea–wheat system (5.8–6.0 mg/kg), suggesting that inclusion of pigeon pea may help to minimise NO3-N leaching to deeper soil profile layers. In plots of pigeon pea, soil organic carbon at 0–15 cm and 15–30 cm soil depths was increased at the end of the experiment compared with the initial organic carbon content. With continuous rice–wheat cropping, the bulk density of soil increased over the initial bulk density, at different soil profile depths in general, and at 30–45 cm soil depth in particular. Inclusion of pigeon pea in the system maintained soil bulk density at its initial level, and thus eliminated sub-surface soil compaction. Despite these advantages of pigeon pea over rice as a preceding crop to wheat, permanent substitution of rice with pigeon pea in rice–wheat system is unlikely, because rice is a staple foodgrain crop in India. Nonetheless, decline in wheat productivity owing to puddling-induced soil constraints that arise on continuous rice–wheat systems could be minimised by introduction of pigeon pea into the system at longer time intervals.

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