Standard operating procedure for soil total carbon
Dumas dry combustion method
Global Soil Laboratory Network GLOSOLAN
GLOSOLAN-SOP-03
SOIL TOTAL CARBON Dumas dry combustion method
Version number : 1 Page 1 of 10
Effective date : October 28, 2019
Modify by Revision Approved Date Validated Date
GLOSOLAN SOP Tech. W.G.
Leaders: F. Bertsch, Costa Rica, and M. Ostinelli, Argentina
3rd GLOSOLAN
meeting
3rd GLOSOLAN
meeting
27 October 2019
SOIL TOTAL CARBON Dumas dry combustion method
VERSION HISTORY
N° Date Description of the modification Type of modification
01 30 July 2019 Finalization of the draft version Compilation of all inputs received
by RESOLANs
02 28 October 2019 Final review of the SOP at the 3rd
GLOSOLAN meeting
Revision of SOP steps, final
discussion and agreement
03
04
Etc.
Global Soil Laboratory Network GLOSOLAN
GLOSOLAN-SOP-03
SOIL TOTAL CARBON Dumas dry combustion method
Version number : 1 Page 2 of 10
Effective date : October 28, 2019
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GLOSOLAN SOP Tech. W.G.
Leaders: F. Bertsch, Costa Rica, and M. Ostinelli, Argentina
3rd GLOSOLAN
meeting
3rd GLOSOLAN
meeting
27 October 2019
Contents 1. Brief introduction to total carbon..................................................................................................... 3 2. Scope and field of application ........................................................................................................... 3 3. Principle .............................................................................................................................................. 3 4. Apparatus ........................................................................................................................................... 4 5. Materials ............................................................................................................................................. 4 6. Health and safety ............................................................................................................................... 4 7. Sample preparation ........................................................................................................................... 4 8. Procedure ........................................................................................................................................... 5
8.1. Calibration of the apparatus ...................................................................................................... 5
8.2. Determination of the total carbon (TC) content ....................................................................... 5
9. Calculation .......................................................................................................................................... 5 10. Quality assurance/Quality control ................................................................................................. 5
10.1. Precision test ............................................................................................................................. 5
10.2. Trueness test ............................................................................................................................. 6
10.3. Control chart ............................................................................................................................. 7
11. Reference documents ...................................................................................................................... 7 12. Appendix I.—Acknowledgments .................................................................................................... 8 13. Appendix II.—List of authors .......................................................................................................... 8 14. Appendix III.—Contributing laboratories ..................................................................................... 8
Global Soil Laboratory Network GLOSOLAN
GLOSOLAN-SOP-03
SOIL TOTAL CARBON Dumas dry combustion method
Version number : 1 Page 3 of 10
Effective date : October 28, 2019
Modify by Revision Approved Date Validated Date
GLOSOLAN SOP Tech. W.G.
Leaders: F. Bertsch, Costa Rica, and M. Ostinelli, Argentina
3rd GLOSOLAN
meeting
3rd GLOSOLAN
meeting
27 October 2019
1. Brief introduction to total carbon
Analysis and quantification of total soil carbon (TC) is necessary to estimate soil organic matter
content, which is a useful parameter when evaluating the productivity of a natural system.
Quantification of TC can be used to monitor soil carbon (C) stocks and to evaluate the role and
effectiveness of C sequestration to mitigate climate change.
Several methods are used to quantify soil C. The Dumas dry combustion method determines total
carbon, representing all chemical forms of C in the soil. Other methods may be used to quantify the
various forms of carbon. For example, the Walkley & Black method measures oxidizable organic
carbon.
For analysis of TC by dry combustion, an automatic chemical analyser, commonly known as an
autoanalyzer, is used. Advantages of using an autoanalyzer are increased accuracy and versatility. An
autoanalyzer can be used to quantify carbon, nitrogen, and sulfur. Disadvantages of using an
autoanalyzer are equipment initial cost, operating and maintenance costs, and the lower number of
labs using an autoanalyzer worldwide.
Additional care must be taken during sample preparation if quantifying TC by the Dumas dry
combustion method. A very small sample is used, which requires the samples to be well
homogenized.
2. Scope and field of application
This standard operating procedure (SOP) describes, in general terms, quantification of TC content in
soil samples by an autoanalyzer. The procedure measures both organic C and inorganic C together.
To quantify the organic C fraction only, the inorganic C fraction must be removed or quantified prior to
autoanalyzer analysis. Alternatively, the inorganic C can be quantified separately and then subtracted
from the TC.
3. Principle
This method is based on the Dumas dry combustion principle. The sample is burned at high
temperature (between 900 and 1000 °C or 1400 and 1600 °C) in an atmosphere of pure oxygen.
Under these conditions, all C-containing compounds are completely decomposed and converted into
carbon oxides (mainly carbon dioxide). The autoanalyzer measures and reports the TC value based
on the concentration of carbon oxides present using various procedures (for example, a C gas
detector and thermal differences between gas columns).
Global Soil Laboratory Network GLOSOLAN
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SOIL TOTAL CARBON Dumas dry combustion method
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3rd GLOSOLAN
meeting
3rd GLOSOLAN
meeting
27 October 2019
4. Apparatus
1. Autoanalyzer for C, with all specific accessories and consumables, including appropriate
detection system.
The equipment might also analyse N and S, depending on the manufacturer and model.
2. Analytical balance, ±0.0001 g, to weigh samples and reference materials.
3. Milling system that meets the requirements of the autoanalyzer manufacturer.
4. Crucible set (if needed), depending on the sample size used by the autoanalyzer.
5. Materials
1. Certified Reference Material (CRM) with known C content to calibrate the autoanalyzer.
The CRM may vary depending on autoanalyzer manufacturer. Aspartic acid, EDTA,
acetanilide, or soil samples with certified total C content may be used.
2. Oxygen gas (O2), along with reference or carrier gases (He, for example), of very high
purity (greater than 99.99%).
3. Consumables specific to the autoanalyzer.
6. Health and safety
This SOP does not imply the direct use of dangerous chemical reagents, but appropriate safety
precautions are necessary. Catalyser residues are toxic and must be disposed of properly. Gloves, lab
coats, and eye protection must be worn when handling reagents and samples. When a special
reagent is used (for example, a reference material for equipment control), consult the material safety
data sheet (MSDS) and conduct a risk assessment. Take necessary precautions when handling
compressed gasses and high-temperature equipment. Follow the manufacturer’s safety guidelines
when operating the autoanalyzer.
7. Sample preparation
Follow the sample preparation instructions provided by the manufacturer for use of the autoanalyzer.
Probably, a representative portion of the soil sample that was previously treated (dried and sieved to
2 mm) must be porfirised (grind fine and homogeneously) until the entire fraction passes through a
sieve of inferior size. Typically, a representative subsample is taken from the bulk sample and milled to
a sufficiently fine mesh size. Ensure that milling equipment and sieves do not introduce contamination
to the samples.
Global Soil Laboratory Network GLOSOLAN
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SOIL TOTAL CARBON Dumas dry combustion method
Version number : 1 Page 5 of 10
Effective date : October 28, 2019
Modify by Revision Approved Date Validated Date
GLOSOLAN SOP Tech. W.G.
Leaders: F. Bertsch, Costa Rica, and M. Ostinelli, Argentina
3rd GLOSOLAN
meeting
3rd GLOSOLAN
meeting
27 October 2019
8. Procedure
8.1. Calibration of the apparatus
Calibrate the equipment as described in the autoanalyzer instruction manual. Use a CRM provided or
recommended by the manufacturer (soil, acetanilide, calcium carbonate, EDTA, glucose anhydrous,
etc). The CRM should cover the range of TC typically found in test samples. Store all CRM as
indicated by the manufacturer label.
Replicated blanks must also be analysed to determine the baseline according the specific equipment
procedure.
8.2. Determination of the total carbon (TC) content
Because the analysis procedure varies between manufacturer’s, analyse samples according to the
manufacturer’s guidelines for soil analysis.
The mass of sample weighed is dependent on the TC of the sample and the linear range of the
autoanalyzer.
To check autoanalyzer performance, CRM, control samples, and blanks should be incorporated at
regular intervals in each test batch. The number and frequency of control and check samples depends
on the method used and the calibration stability of the autoanalyzer.
9. Calculation
Report TC using the International Units System as: grams of C (g) per kilogram (kg) of soil, g/kg.
Results must be reported on an ovendry soil basis.
The number of decimals reported must conform to the conventional rules of maintaining 3 numbers:
values greater than 100, no decimal reported;
values between 10 and 100, 1 decimal (0.1) reported; and
values less than 10, 2 decimals (0.01) reported.
10. Quality assurance/Quality control
10.1. Precision test
- 5 percent of the samples in a test batch must be replicates to guarantee at least one duplicate
sample if the batch is small.
Global Soil Laboratory Network GLOSOLAN
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SOIL TOTAL CARBON Dumas dry combustion method
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- Calculate the percent relative standard deviation (% RSD) to determine precision.
Where: s = standard deviation of the replicate result x̄ = mean - Compare the result with the previously specified precision.
The acceptance requirements for precision testing must be defined by the equipment used,
environmental conditions, and other testing factors and by the specifications or requirements for the
information use and agronomic criteria.
If the precision test fails, the cause of the failure must be identified and corrective or preventive actions
must be developed.
10.2. Trueness test
10.2.1. Recovery test
- Perform triplicate analysis of Certified Reference Material of the analysed matrix (soil) (CRMs)
or an Internal Reference Material (IRM), in accordance with the present SOP.
Note: To assess instrument performance, this procedure should be replicated with different levels of
TC. Different levels can be selected by using CRM with different concentrations of TC or by simply
weighing different masses of the same CRM.
- Calculate the percent recovery based on the equation below.
- Compare the result with the recovery target (%), which is predefined for the usual range of work.
The recovery target must be defined for the usual range of work. The definition should consider the
working conditions (for example the characteristics of the equipment used and the environmental
conditions). It should also consider the specifications or requirements for the given use of the
information and for any agronomic criteria. The recovery can also be considered acceptable if it is
within the 95% confidence interval reported for the target value of the CRMs.
If the recovery test fails, the cause of the failure must be identified and corrective or preventive actions
must be developed.
Global Soil Laboratory Network GLOSOLAN
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SOIL TOTAL CARBON Dumas dry combustion method
Version number : 1 Page 7 of 10
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Modify by Revision Approved Date Validated Date
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Leaders: F. Bertsch, Costa Rica, and M. Ostinelli, Argentina
3rd GLOSOLAN
meeting
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10.2.2. Interlaboratory comparison
The laboratory must participate, at least once a year, in interlaboratory proficiency tests.
If the obtained result is questionable or unsatisfactory, it is necessary to carry out an evaluation,
identify the root cause of the problem, and develop corrective and preventive actions.
10.3. Control chart
- Perform the replicate analysis of a control sample or an IRM in a test batch of samples.
- Plot the result in a control chart.
- Monitor the results.
If results are out of specified limits (or tend to be so), an evaluation must be made. The cause of the
noncompliance must be identified, and corrective and preventive actions must be developed.
11. Reference documents
Eurachem. 2014. The fitness for purpose of analytical methods. A laboratory guide to method
validation and related topics. Second Edition
Karla, Y.P. 1998. Handbook of reference methods for plant analysis. CRC Press.
Leco Corporation. 2004. Leco Truspec CN Determinator instruction manual
Nelson, D.W. & Sommers, L.E. 1996. Total carbon, organic carbon and organic matter. In D.L.
Sparks (Ed.), Soil Science Society of America, book series 5. Methods of soil analysis, Part 3,
Chemical methods. Madison, Wisconsin: Soil Science Society of America, Inc.
Global Soil Laboratory Network GLOSOLAN
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SOIL TOTAL CARBON Dumas dry combustion method
Version number : 1 Page 8 of 10
Effective date : October 28, 2019
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GLOSOLAN SOP Tech. W.G.
Leaders: F. Bertsch, Costa Rica, and M. Ostinelli, Argentina
3rd GLOSOLAN
meeting
3rd GLOSOLAN
meeting
27 October 2019
12. Appendix I.—Acknowledgments
GLOSOLAN thanks the Latin American Soil Laboratory Network (LATSOLAN); Ms. Floria Bertsch,
LATSOLAN Chair; and Ms. Miriam Ostinelli for preparing the first draft of this SOP. GLOSOLAN also
thanks the participants in the 3rd GLOSOLAN meeting (28-30 October 2019) for reviewing this SOP.
13. Appendix II.—List of authors
Main authors (in alphabetical order):
Mr. Rob De Hayr, Department of Environment and Science, Science Division, Chemistry
Centre, Australia
Mr. Chris Lee, Kellogg Soil Survey Laboratory, United States of America
Ms. Floria Bertsch, CIA-UCR, Costa Rica
Ms. Miriam Ostinelli, Laboratorio de Suelos CIRN-CNIA-INTA, Argentina
Ms. Nopmanee Suvannang, GLOSOLAN Chair, Thailand
14. Appendix III.—Contributing laboratories
GLOSOLAN thanks the following laboratories for completing the GLOSOLAN form on the method and
providing information on their standard operating procedure for the Dumas dry combustion method.
This information was used as a baseline for the global harmonization.
From the Asian region:
Bureau of Soils and Water Management Laboratory Services Division, Philippines
Charles Renard Analytical Laboratory, India
DA Regional Field Office 3-ILD-Regional Soils Laboratory, Philippines
DOA, Malaysia
Fauji Fertilizer Company’s Soil Testing Labs, Pakistan
Horticultural Crops Research and Development Institute, Department of Agriculture, Sri Lanka
ICAR-IISS, Bhopal, India
NIAES, NARO, Japan
Office of Science for Land Development, Land Development Department, Thailand
Soil and Plant Analysis Laboratory, Myanmar
Soil Lab, ISRI, Indonesia
SRDI, Bangladesh
From the Pacific region:
Office of Environment and Heritage, Soil Health & Archive, Australia
The University of the South Pacific, Alafua Campus, Samoa
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SOIL TOTAL CARBON Dumas dry combustion method
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3rd GLOSOLAN
meeting
3rd GLOSOLAN
meeting
27 October 2019
From the Near East and North African region:
None
From the African region:
Department of Agricultural Research, Lesotho
Farming & Engineering Services (FES), Malawi
IRD, Senegal
Laboratoire d’Analyse des Sols et des Végétaux – LSV, Togo
Laboratoire des Radioisotopes, Madagascar
Laboratorio regional de analise de solos e plantas, Mozambique
LASEVE, Niger
LASPEE of IRAD, Cameroon
National laboratory for diagnosis and quality control of agricultural products and inputs,
Cameroon
Soil Research Institute Analytical Services Laboratory, Ghana
TARI Mlingano LAB, Tanzania
Zimbabwe Sugar Association Experiment Station, Zimbabwe
From the European region:
Aarhus University, AGRO University laboratory, Denmark
AGES - Institute for Sustainable Plant Production, Department for Soil Health and Plant
Nutrition, Austria
Agricultural Institute of Slovenia, Slovenia
Andrija Stampar Teaching Institute of Public Health, Croatia
BRGM, France
Chemisch Biologisch Laboratorium Bodem, Netherlands
Environmental Research Laboratory, United Kingdom
Federal agency for water management (BAW), Institute for land and water management
research (IKT), Austria
Institute of Soil Research, Austria
Instituto Politécnico de Castelo Branco/Escola Superior Agrária, Portugal
Instituto Superior de Agronomia (ISA_PT), Portugal
IRD, France
Laboratory of Biogeochemistry and Environmental Protection, University of Warsaw, Biological
and Chemical Research Centre, Poland
LSFRI Silava, Latvia
Rothamsted Research, United Kingdom
UKZUZ, Czech Republic
Universidade de Évora, Portugal
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University of Zagreb Faculty of Agriculture, Croatia
University of Zagreb, Faculty of Agriculture, Department of General Agronomy, Croatia
VITO, Belgium
From the Eurasian region:
Institute of Biology of Komi Scientific Center of the Ural Branch, Russian Federation
Soil Science Faculty, Lomonosov Moscow State University, Russian Federation
From Latin America:
Colegio de Postgraduados, Mexico
ECOSUR, Mexico
Embrapa, Brazil
INTA - Inst. de Suelos. Laboratory – LabIS, Argentina
Laboratorio de Suelos UCTB Camagüey, Cuba
Laboratorio de Suelos y Aguas de la Dirección General de Recursos Naturales - Ministerio de
Ganadería Agricultura y Pesca (DGRN-MGAP), Uruguay
Soil Health, Plant Tissue and Water Laboratory, Jamaica
Universidad de Concepción Facultad de Agronomía departamento de Suelos, Laboratorio
Químico de Suelos y Plantas, Chile
From North America:
KSSL, United States
GLOSOLANGLOBAL SOIL LABORATORY NETWORK
The Global Soil Partnership (GSP) is a globally recognized mechanism established in 2012. Our mission is to position soils in the Global Agenda through collective action. Our key objectives are to promote Sustainable Soil Management (SSM) and improve soil govern-ance to guarantee healthy and productive soils, and support the provision of essential ecosystem services towards food security and improved nutrition, climate change adapta-tion and mitigation, and sustainable develop-ment.
GLOSOLAN is a Global Soil Laboratory Network which aims to harmonize soil analysis methods and data so that soil informa-tion is comparable and interpretable across laboratories, countries and regions. Established in 2017, it facilitates networking and capacity development through coopera-tion and information sharing between soil laboratories with di �erent levels of experience. Joining GLOSOLAN is a unique opportunity to invest in quality soil laboratory data for a sustainable and food secure world.
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