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REVIEW

Measuring soil organic carbon: which technique and where to from here?

Timothy J. Johns A B , Michael J. Angove A and Sabine Wilkens A
+ Author Affiliations
- Author Affiliations

A La Trobe University, School of Pharmacy and Applied Science, PO Box 199, Bendigo, Vic. 3552, Australia.

B Corresponding author. Email: T.Johns@latrobe.edu.au

Soil Research 53(7) 717-736 https://doi.org/10.1071/SR14339
Submitted: 28 November 2014  Accepted: 13 April 2015   Published: 27 October 2015

Abstract

This review compares and contrasts analytical techniques for the measurement of total soil organic carbon (TOC). Soil TOC is seen to be a highly important health and quality indicator for soils, as well as having the potential to sequester atmospheric carbon. Definition of the form of organic carbon measured by a given method is vital to the selection of appropriate methodology, as well as the understanding of what exactly is being measured. Historically, studies of TOC have ranged from basic measures, such as colour and gravimetric analyses, to dry and wet oxidation techniques. In more recent times, various spectroscopic techniques and the application of remote or mobile approaches have gained prominence. The different techniques, even the oldest ones, may have their place in current research depending on research needs, the available time, budget and access to wider resources. This review provides an overview of the various methods, highlights advantages, limitations and research opportunities and provides an indication of what the method actually measures so that meaningful comparisons can be made.


References

Allison LE (1960) Wet-combustion apparatus and procedure for organic and inorganic carbon in soil. Soil Science Society of America Journal 24, 36–40.
Wet-combustion apparatus and procedure for organic and inorganic carbon in soil.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF3cXmsVCisA%3D%3D&md5=39e90b29b4e5bfa9c9a814deb1d1259cCAS |

Ames JW, Gaither EW (1914) Determination of carbon in soils and soil extracts. Journal of Industrial and Engineering Chemistry 6, 561–564.
Determination of carbon in soils and soil extracts.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaC2cXitFSksA%3D%3D&md5=b3ef47e8d4afbc1275add3eead37c599CAS |

Artursson V, Finlay RD, Jansson JK (2006) Interactions between arbuscular mycorrhizal fungi and bacteria and their potential for stimulating plant growth. Environmental Microbiology 8, 1–10.
Interactions between arbuscular mycorrhizal fungi and bacteria and their potential for stimulating plant growth.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28XitFSgtb0%3D&md5=0e0ca4098153480bea9501e1be3d8a11CAS | 16343316PubMed |

Baes AU, Bloom PR (1989) Diffuse reflectance and transmission Fourier transform infrared (DRIFT) spectroscopy of humic and fulvic acids. Soil Science Society of America Journal 53, 695–700.
Diffuse reflectance and transmission Fourier transform infrared (DRIFT) spectroscopy of humic and fulvic acids.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL1MXltFChur4%3D&md5=cfe80d249c55bc4ce62e56a06ff68affCAS |

Baldock JA (2007) ‘Nutrient cycling in terrestrial ecosystems.’ (Springer-Verlag: Berlin, Heidelberg)

Baldock JA, Hawke B, Sanderman J, Macdonald LM (2013a) Predicting contents of carbon and its component fractions in Australian soils from diffuse reflectance mid-infrared spectra. Soil Research 51, 577–595.
Predicting contents of carbon and its component fractions in Australian soils from diffuse reflectance mid-infrared spectra.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3sXhvF2ktbjF&md5=2a6c39456d630d51199f3e3996673613CAS |

Baldock JA, Sanderman J, Macdonald LM, Puccini A, Hawke B, Szarvas S, McGowan J (2013b) Quantifying the allocation of soil organic carbon to biologically significant fractions. Soil Research 51, 561–576.
Quantifying the allocation of soil organic carbon to biologically significant fractions.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3sXhvF2ktbbL&md5=6ac92230ef0514ae7e73a4914c1b210eCAS |

Ball DF (1964) Loss-on-ignition as an estimate of organic matter and organic carbon in non-calcareous soils. Journal of Soil Science 15, 84–92.
Loss-on-ignition as an estimate of organic matter and organic carbon in non-calcareous soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF2cXkt1Whtrg%3D&md5=e33152f2eb2f7127916e409738aba3dbCAS |

Barrow CJ (2012) Biochar: potential for countering land degradation and for improving agriculture. Applied Geography 34, 21–28.
Biochar: potential for countering land degradation and for improving agriculture.Crossref | GoogleScholarGoogle Scholar |

Bartholomeus H, Kooistra L, Stevens A, van Leeuwen M, van Wesemael B, Ben-Dor E, Tychon B (2011) Soil organic carbon mapping of partially vegetated agricultural fields with imaging spectroscopy. International Journal of Applied Earth Observation and Geoinformation 13, 81–88.
Soil organic carbon mapping of partially vegetated agricultural fields with imaging spectroscopy.Crossref | GoogleScholarGoogle Scholar |

Baumgardner MF, Silva LF, Biehl LL, Stoner ER (1985) Reflectance properties of soils. In ‘Advances in agronomy’. Vol. 38. (Ed. NC Brady) pp. 1–44. (Academic Press: Orlando, FL)

Belkov MV, Burakov VS, De Giacomo A, Kiris VV, Raikov SN, Tarasenko NV (2009) Comparison of two laser-induced breakdown spectroscopy techniques for total carbon measurement in soils. Spectrochemica Acta Part B 64, 899–904.
Comparison of two laser-induced breakdown spectroscopy techniques for total carbon measurement in soils.Crossref | GoogleScholarGoogle Scholar |

Bellon-Maurel V, McBratney A (2011) Near-infrared (NIR) and mid-infrared (MIR) spectroscopic techniques for assessing the amount of carbon stock in soils: critical review and research perspectives. Soil Biology & Biochemistry 43, 1398–1410.
Near-infrared (NIR) and mid-infrared (MIR) spectroscopic techniques for assessing the amount of carbon stock in soils: critical review and research perspectives.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXmtFCrsro%3D&md5=be8801c6d7fc462f31ca2e1283e52a6aCAS |

Bellon-Maurel V, Fernandez-Ahumada E, Palagos B, Roger J-M, McBratney A (2010) Critical review of chemometric indicators commonly used for assessing the quality of the prediction of soil attributes by NIR spectroscopy. Trends in Analytical Chemistry 29, 1073–1081.
Critical review of chemometric indicators commonly used for assessing the quality of the prediction of soil attributes by NIR spectroscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXhtFGqsLnP&md5=d6be2878662cd72dbd01ef209ec400c7CAS |

Ben-Dor E, Banin A (1989) Determination of organic matter content in arid‐zone soils using a simple ‘loss‐on‐ignition’ method. Communications in Soil Science and Plant Analysis 20, 1675–1695.
Determination of organic matter content in arid‐zone soils using a simple ‘loss‐on‐ignition’ method.Crossref | GoogleScholarGoogle Scholar |

Ben-Dor E, Banin A (1995) Near-infrared analysis as a rapid method to simultaneously evaluate several soil properties. Soil Science Society of America Journal 59, 364–372.
Near-infrared analysis as a rapid method to simultaneously evaluate several soil properties.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2MXlt12qu74%3D&md5=b9a4a7ab6564561f9ccd2e5e2594c198CAS |

Ben-Dor E, Patkin K, Banin A, Karnieli A (2002) Mapping of several soil properties using DAIS-7915 hyperspectral scanner data: a case study over clayey soils in Israel. International Journal of Remote Sensing 23, 1043–1062.
Mapping of several soil properties using DAIS-7915 hyperspectral scanner data: a case study over clayey soils in Israel.Crossref | GoogleScholarGoogle Scholar |

Ben-Dor E, Chabrillat S, Dematte JAM, Taylor GR, Hill J, Whiting ML, Sommer S (2009) Using imaging spectroscopy to study soil properties. Remote Sensing of Environment 113, S38–S55.
Using imaging spectroscopy to study soil properties.Crossref | GoogleScholarGoogle Scholar |

Bisutti I, Hilke I, Raessler M (2004) Determination of total organic carbon: an overview of current methods. Trends in Analytical Chemistry 23, 716–726.
Determination of total organic carbon: an overview of current methods.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXhtVCmtbbO&md5=c7bda38eca2032779a354499253f5288CAS |

Blair GJ, Lefroy RDB, Lisle L (1995) Soil carbon fractions based on their degree of oxidation and the development of a carbon management index for agricultural systems. Australian Journal of Agricultural Research 46, 1459–1466.
Soil carbon fractions based on their degree of oxidation and the development of a carbon management index for agricultural systems.Crossref | GoogleScholarGoogle Scholar |

Blouin M, Hodson ME, Delgado EA, Baker G, Brussaard L, Butt KR, Dai J, Dendooven L, Peres G, Tondoh JE, Cluzeau D, Brun JJ (2013) A review of earthworm impact on soil function and ecosystem services. European Journal of Soil Science 64, 161–182.
A review of earthworm impact on soil function and ecosystem services.Crossref | GoogleScholarGoogle Scholar |

Bowers SA, Hanks RJ (1965) Reflection of radiant energy from soils. Soil Science 100, 130–138.
Reflection of radiant energy from soils.Crossref | GoogleScholarGoogle Scholar |

Bricklemyer RS, Brown DJ (2010) On-the-go VisNIR: potential and limitations for mapping soil clay and organic carbon. Computers and Electronics in Agriculture 70, 209–216.
On-the-go VisNIR: potential and limitations for mapping soil clay and organic carbon.Crossref | GoogleScholarGoogle Scholar |

Bricklemyer RS, Lawrence RL, Miller RM, Battogtokh N (2007) Monitoring and verifying agricultural practices related to soil carbon sequestration with satellite imagery. Agriculture, Ecosystems & Environment 118, 201–210.
Monitoring and verifying agricultural practices related to soil carbon sequestration with satellite imagery.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28Xht1CnsLrJ&md5=11fef2e4f1b9b67db95fea84ad090aa9CAS |

Bricklemyer RS, Brown DJ, Barefield JE, Clegg SM (2011) Intact soil core total, inorganic, and organic carbon measurement using laser-induced breakdown spectroscopy. Soil Science Society of America Journal 75, 1006–1018.
Intact soil core total, inorganic, and organic carbon measurement using laser-induced breakdown spectroscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXnsFylsbY%3D&md5=aa14e30165c6fc68c3063a809ce23a8eCAS |

Brock WH (2013) Justus, baron von Liebig. In ‘Encyclopaedia Britanica’. Available at: www.britannica.com/biography/Justus-Freiherr-von-Liebig (accessed 4 April 2014).

Brown DJ, Shepherd KD, Walsh MG, Dewayne Mays M, Reinsch TG (2006) Global soil characterization with VNIR diffuse reflectance spectroscopy. Geoderma 132, 273–290.
Global soil characterization with VNIR diffuse reflectance spectroscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28XksFaqsbw%3D&md5=8381ce8d1f3c2a918ce3e7139679e207CAS |

Brunet D, Barthes BG, Chotte J-L, Feller C (2007) Determination of carbon and nitrogen contents in Alfisols, Oxisols and Ultisols from Africa and Brazil using NIRS analysis: effects of sample grinding and set heterogeneity. Geoderma 139, 106–117.
Determination of carbon and nitrogen contents in Alfisols, Oxisols and Ultisols from Africa and Brazil using NIRS analysis: effects of sample grinding and set heterogeneity.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXjvVagtb4%3D&md5=8be13279219135e0101211d7576cf493CAS |

Calvelo Pereira R, Camps Arbestain M, Kaal J, Vasquez Suero M, Sevilla M, Hindmarsh J (2014) Detailed carbon chemistry in charcoals from pre-European Māori gardens of New Zealand as a tool for understanding biochar stability in soils. European Journal of Soil Science 65, 83–95.
Detailed carbon chemistry in charcoals from pre-European Māori gardens of New Zealand as a tool for understanding biochar stability in soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXnt1egtg%3D%3D&md5=72d1407c3aafff22332f2e730caa4559CAS |

Cameron FK (1905) A comparison of the organic matter in different soil types. Journal of the American Chemical Society 27, 256–258.
A comparison of the organic matter in different soil types.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaD28XitFGn&md5=7d8a91fa0e75e58bd659c2d49e67e454CAS |

Cameron FK, Breazeale JF (1904) The organic matter in soils and subsoils. Journal of the American Chemical Society 26, 29–45.
The organic matter in soils and subsoils.Crossref | GoogleScholarGoogle Scholar |

Cannell RQ, Hawes JD (1994) Trends in tillage practices in relation to sustainable crop production with special reference to temperate climates. Soil & Tillage Research 30, 245–282.
Trends in tillage practices in relation to sustainable crop production with special reference to temperate climates.Crossref | GoogleScholarGoogle Scholar |

Chatterjee A, Lal R, Wielopolski L, Martin MZ, Ebinger MH (2009) Evaluation of different soil carbon determination methods. Critical Reviews in Plant Sciences 28, 164–178.
Evaluation of different soil carbon determination methods.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXktFClsrc%3D&md5=27469d7b58150c9155e33a59f426ca17CAS |

Chen F, Kissel DE, West LT, Adkins W (2000) Field-scale mapping of surface soil organic carbon using remotely sensed imagery. Soil Science Society of America Journal 64, 746–753.
Field-scale mapping of surface soil organic carbon using remotely sensed imagery.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3cXms1eqtLw%3D&md5=76f84fde97bdf7d3c4e39555ddb5b4bfCAS |

Chia CH, Munroe P, Joseph S, Lin Y (2010) Microscopic characterisation of synthetic Terra Preta. Australian Journal of Soil Research 48, 593–605.
Microscopic characterisation of synthetic Terra Preta.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXht1Sru7nF&md5=bb8998815d95b48c679dee965beb5475CAS |

Christy CD (2008) Real-time measurement of soil attributes using on-the-go near infrared reflectance spectroscopy. Computers and Electronics in Agriculture 61, 10–19.
Real-time measurement of soil attributes using on-the-go near infrared reflectance spectroscopy.Crossref | GoogleScholarGoogle Scholar |

Ciais P, Sabine C, Bala G, Bopp L, Brovkin V, Canadell J, Chhabra A, DeFries R, Galloway J, Heimann M, Jones C, Le Quere C, Myneni RB, Piao S, Thornton P (2013) Carbon and other biogeochemical cycles. In ‘Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change’. (Eds TF Stocker, D Qin, G-K Plattner, M Tignor, SK Allen, J Boschung, A Nauels, Y Xia, V Bex, PM Midgle) pp. 465–570. (Cambridge University Press: Cambridge, UK and New York, USA)

Clark NA, Ogg CL (1942) A wet combustion method for determining total carbon in soils. Soil Science 53, 27–36.
A wet combustion method for determining total carbon in soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaH38XhvFehsg%3D%3D&md5=2b32f208a3339aa0681e1bd374f0e992CAS |

Conyers MK, Poile GJ, Oates AA, Waters D, Chan KY (2011) Comparison of three carbon determination methods on naturally occurring substrates and the implication for the quantification of ‘soil carbon’. Soil Research 49, 27–33.
Comparison of three carbon determination methods on naturally occurring substrates and the implication for the quantification of ‘soil carbon’.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXit1Wgu78%3D&md5=fbc02c30cf030315f72090895e2019f5CAS |

Cremers DA, Ebinger MH, Breshears DD, Unkefer PJ (2001) Measuring total soil carbon with laser-induced breakdown spectroscopy (LIBS). Journal of Environmental Quality 30, 2202–2206.
Measuring total soil carbon with laser-induced breakdown spectroscopy (LIBS).Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD38Xht1Slt7g%3D&md5=af79678801591031313caae640b8e386CAS | 11790033PubMed |

Croft H, Kuhn NJ, Anderson K (2012) On the use of remote sensing techniques for monitoring spatio-temporal soil organic carbon dynamics in agricultural systems. Catena 94, 64–74.
On the use of remote sensing techniques for monitoring spatio-temporal soil organic carbon dynamics in agricultural systems.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38XkvVKltL8%3D&md5=69b0dc53121411397f13e10f2b093e88CAS |

Culman SW, Snapp SS, Freeman MA, Schipanski ME, Beniston J, Lal R, Drinkwater LE, Franzluebbers AJ, Glover JD, Grandy AS, Lee J, Six J, Maul JE, Mirsky SB, Spargo JT, Wander MM (2012) Permanganate oxidizable carbon reflects a processed soil fraction that is sensitive to management. Soil Science Society of America Journal 76, 494–504.
Permanganate oxidizable carbon reflects a processed soil fraction that is sensitive to management.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38XktFOhs7g%3D&md5=eb8d3b67b38f3d0717c9f2788adc4191CAS |

da Silva RM, Milori DMBP, Ferreira EC, Krug FJ, Martin-Neto L (2008) Total carbon measurement in tropical soil sample. Spectrochemica Acta Part B 63, 1221–1224.
Total carbon measurement in tropical soil sample.Crossref | GoogleScholarGoogle Scholar |

Dalal RC, Henry RJ (1986) Simultaneous determination of moisture, organic carbon and total nitrogen by near infrared reflectance spectrophotometry. Soil Science Society of America Journal 50, 120–123.
Simultaneous determination of moisture, organic carbon and total nitrogen by near infrared reflectance spectrophotometry.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL28Xht1yrtbw%3D&md5=47c898d6e41409fb9e881d9a83dfeabaCAS |

Dalal RC, Mayer RJ (1986) Long term trends in fertility of soils under continuous cultivation and cereal cropping in southern Queensland. I. Overall changes in soil properties and trends in winter cereal yields. Australian Journal of Soil Research 24, 265–279.
Long term trends in fertility of soils under continuous cultivation and cereal cropping in southern Queensland. I. Overall changes in soil properties and trends in winter cereal yields.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL28XkvFKmsL8%3D&md5=ff4db3af81bf05a7fdd15051160443fdCAS |

Degtjareff WT (1930) Determining soil organic matter by means of hydrogen peroxide and chromic acid. Soil Science 29, 239–246.
Determining soil organic matter by means of hydrogen peroxide and chromic acid.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaA3cXis1Gksw%3D%3D&md5=167ce1d0eb60a44f7e812fb02a79caa9CAS |

Ebinger MH, Norfleet ML, Breshears DD, Cremers DA, Ferris MJ, Unkefer PJ, Lamb MS, Goddard KL, Meyer CW (2003) Extending the applicability of laser-induced breakdown spectroscopy for total soil carbon measurement. Soil Science Society of America Journal 67, 1616–1619.
Extending the applicability of laser-induced breakdown spectroscopy for total soil carbon measurement.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3sXnsVGksrg%3D&md5=3778f35c6373200d14a4c4fde1836de1CAS |

Elementar (2014) Vario MACRO cube. Available at: www.elementar.de/en/products/elementar-products/vario-macro-cube.html (accessed 9 July 2014).

Fairman HS, Brill MH, Hemmindger H (1997) How the CIE 1931 color-matching functions were derived from Wright–Guild data. Color Research and Application 22, 11–23.
How the CIE 1931 color-matching functions were derived from Wright–Guild data.Crossref | GoogleScholarGoogle Scholar |

Falahat S, Koble T, Schumann O, Waring C, Watt G (2012) Development of a surface scanning soil analysis instrument. Applied Radiation and Isotopes 70, 1107–1109.
Development of a surface scanning soil analysis instrument.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38XosFeqs78%3D&md5=cf1deb60a62d574114c636d7788fd5b1CAS | 22204784PubMed |

Farmer VC (1957) Effects of grinding during the preparation of alkali halide disks. Spectrochemica Acta 8, 374–389.
Effects of grinding during the preparation of alkali halide disks.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaG2sXmtVCgug%3D%3D&md5=26b91d61e20f12a00a4c54fc6334b001CAS |

Fidêncio PH, Poppi RJ, de Andrade JC (2002) Determination of organic matter in soils using radial basis function networks and near infrared spectroscopy. Analytica Chimica Acta 453, 125–134.
Determination of organic matter in soils using radial basis function networks and near infrared spectroscopy.Crossref | GoogleScholarGoogle Scholar |

Franzmeier DP (1988) Relation of organic matter content to texture and colour of Indiana soils. Proceedings of the Indiana Academy of Sciences 98, 463–471.

Genot V, Colinet G, Bock L, Vanvyve D, Reusen Y, Dardenne P (2011) Near infrared reflectance spectroscopy for estimating soil characteristics valuable in the diagnosis of soil fertility. Journal of Near Infrared Spectroscopy 19, 117–138.
Near infrared reflectance spectroscopy for estimating soil characteristics valuable in the diagnosis of soil fertility.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXnvFWksr8%3D&md5=59b11d6d3e1f2203e039907ed416196bCAS |

Gillman GP, Sinclair DF, Beech TA (1986) Recovery of organic carbon by the Walkley and Black procedure in highly weathered soils. Communications in Soil Science and Plant Analysis 17, 885–892.
Recovery of organic carbon by the Walkley and Black procedure in highly weathered soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL28XlvV2qtbg%3D&md5=643be3bab94759add1b48b2b21f598b7CAS |

Glumac NG, Dong WK, Jarrell M (2010) Quantitative analysis of soil organic carbon using laser-induced breakdown spectroscopy: an improved method. Soil Science Society of America Journal 74, 1922–1928.
Quantitative analysis of soil organic carbon using laser-induced breakdown spectroscopy: an improved method.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXhsFahtrzO&md5=06c472e678a08a703f975a94ea907379CAS |

Gomez C, Viscarra Rossel RA, McBratney A (2008) Soil organic carbon prediction by hyperspectral remote sensing and field vis-NIR spectroscopy: an Australian case study. Geoderma 146, 403–411.
Soil organic carbon prediction by hyperspectral remote sensing and field vis-NIR spectroscopy: an Australian case study.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXhtVCgur7K&md5=01520874d81be1c11bc25a2f20aa67f7CAS |

Gómez-Robledo L, Lopez-Ruiz N, Melgosa M, Palma AJ, Fermin Capitan-Vallvey L, Sanchez-Maranon M (2013) Using the mobile phone as Munsell soil-colour sensor: an experiment under controlled illumination conditions. Computers and Electronics in Agriculture 99, 200–208.
Using the mobile phone as Munsell soil-colour sensor: an experiment under controlled illumination conditions.Crossref | GoogleScholarGoogle Scholar |

Gondal MA, Maganda YW, Dastageer MA, Al Adel FF, Naqvi AA, Qahtan TF (2014) Detection of the level of fluoride in the commercially available toothpaste using laser induced breakdown spectroscopy with the marker atomic transition line of neutral fluorine at 731.1 nm. Optics & Laser Technology 57, 32–38.
Detection of the level of fluoride in the commercially available toothpaste using laser induced breakdown spectroscopy with the marker atomic transition line of neutral fluorine at 731.1 nm.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3sXhvVeht77L&md5=9936bcf0c6a1c0ca6517066ea23dc3e3CAS |

Grewal KS, Buchan GD, Sherlock RR (1991) A comparison of three methods of organic carbon determination in some New Zealand soils. Journal of Soil Science 42, 251–257.
A comparison of three methods of organic carbon determination in some New Zealand soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK3MXltlCqsbg%3D&md5=6be907f598814a72a2d33c6b9c368844CAS |

Guerrero C, Zornoza R, Gomez I, Mataix-Beneyto J (2010) Spiking of NIR regional models using samples from target sites: effect of model size on prediction accuracy. Geoderma 158, 66–77.
Spiking of NIR regional models using samples from target sites: effect of model size on prediction accuracy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXnvFWhsrg%3D&md5=18a9f4cd6a95ea34092c3104ca3a01cfCAS |

Harmon RS, DeLucia FC, McManus CE, McMillan NJ, Jenkins TF, Walsh ME, Miziolek A (2006) Laser-induced breakdown spectroscopy: an emerging chemical sensor technology for real-time field-portable, geochemical, mineralogical, and environmental applications. Applied Geochemistry 21, 730–747.
Laser-induced breakdown spectroscopy: an emerging chemical sensor technology for real-time field-portable, geochemical, mineralogical, and environmental applications.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28XktFaqtb0%3D&md5=195da920994fccb1db7e993503e6e4eeCAS |

Heanes DL (1984) Determination of total organic-C in soils by an improved chromic acid digestion and spectrophotometric procedure. Communications in Soil Science and Plant Analysis 15, 1191–1213.
Determination of total organic-C in soils by an improved chromic acid digestion and spectrophotometric procedure.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL2cXmt12itL8%3D&md5=713ec9490fb99b2de59cfcb57528a029CAS |

Henderson TL, Baumgardner MF, Franzmeier DP, Stott DE, Coster DC (1992) High dimensional reflectance analysis of soil organic matter. Soil Science Society of America Journal 56, 865–872.
High dimensional reflectance analysis of soil organic matter.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK38XlsFSjsL4%3D&md5=f7abe85b57a26f53b051712f3a643faaCAS |

Heron G, Barcelona MJ, Andersen ML, Christensen TH (1997) Determination of nonvolatile organic carbon in aquifer solids after carbonate removal by sulfurous acid. Ground Water 35, 6–11.
Determination of nonvolatile organic carbon in aquifer solids after carbonate removal by sulfurous acid.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2sXislaisQ%3D%3D&md5=1187e270977f39821383296586a17fddCAS |

Hunt GR (1977) Spectral signatures of particulate minerals in the visible and near infrared. Geophysics 42, 501–513.
Spectral signatures of particulate minerals in the visible and near infrared.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE2sXlslSmsbw%3D&md5=9fec2111f1571056d038b754c0372351CAS |

Ibáñez-Asensio S, Marques-Mateu A, Moreno-Ramon H, Balasch S (2013) Statistical relationships between soil colour and soil attributes in semiarid areas. Biosystems Engineering 116, 120–129.
Statistical relationships between soil colour and soil attributes in semiarid areas.Crossref | GoogleScholarGoogle Scholar |

Ichoku C, Przyborski P (2014) Hyperion. Available at: http://earthobservatory.nasa.gov/Features/EO1Tenth/page3.php (accessed 25 July 2014).

Irons JR (2014) Landsat Science: The Multispectral Scanner System. Available at: http://landsat.gsfc.nasa.gov/?p=3227 (accessed 23 May 2014).

Islam K, Singh B, McBratney A (2003) Simultaneous estimation of several soil properties by ultra-violet, visible, and near-infrared reflectance spectroscopy. Australian Journal of Soil Research 41, 1101–1114.
Simultaneous estimation of several soil properties by ultra-violet, visible, and near-infrared reflectance spectroscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3sXot1Cgsbs%3D&md5=0604d43755fff146aa44cd734117e353CAS |

Janik LJ, Skjemstad JO (1995) Characterisation and analysis of soils using mid-infrared partial least squares: II. Correlations with some laboratory data. Australian Journal of Soil Research 33, 637–650.
Characterisation and analysis of soils using mid-infrared partial least squares: II. Correlations with some laboratory data.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2MXotlygtbw%3D&md5=7859efc46a0ee1ec0a75aa309afe053aCAS |

Janik LJ, Merry RH, Skjemstad JO (1998) Can mid infrared diffuse reflectance analysis relace soil extractions? Australian Journal of Experimental Agriculture 38, 681–696.
Can mid infrared diffuse reflectance analysis relace soil extractions?Crossref | GoogleScholarGoogle Scholar |

Jenkinson DS (1990) The turnover of organic carbon and nitrogen in soil. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 329, 361–368.
The turnover of organic carbon and nitrogen in soil.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK3MXkslSgtb0%3D&md5=ee1ab6d9590086bd8902959d16d408efCAS |

Jonas JL, Wilson GWT, White PM, Joern A (2007) Consumption of mycorrhizal and saprophytic fungi by Collembola in grassland soils. Soil Biology & Biochemistry 39, 2594–2602.
Consumption of mycorrhizal and saprophytic fungi by Collembola in grassland soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXotVagtLo%3D&md5=ed3ac46bb02a3911b0b813b3a2006b1aCAS |

Kerven GL, Menzies NW, Geyer MD (2000) Analytical methods and quality assurance. Communications in Soil Science and Plant Analysis 31, 1935–1939.
Analytical methods and quality assurance.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3cXmvVGlsLs%3D&md5=4b4984d9921b76ae083eb6d56c51767fCAS |

Kögel-Knabner I (2002) The macromolecular organic composition of plant and microbial residues as inputs to soil organic matter. Soil Biology & Biochemistry 34, 139–162.
The macromolecular organic composition of plant and microbial residues as inputs to soil organic matter.Crossref | GoogleScholarGoogle Scholar |

Konen ME, Jacobs PM, Burras CL, Talaga BJ, Mason JA (2002) Equations for predicting soil organic carbon using loss-on-ignition for north central U.S. soils. Soil Science Society of America Journal 66, 1878–1881.
Equations for predicting soil organic carbon using loss-on-ignition for north central U.S. soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD38XoslKhsb8%3D&md5=a2f5f8ede76a3a39795ec1d30b5264dfCAS |

Konen ME, Burras CL, Sandor JA (2003) Organic carbon, texture, and quantitative color measurement relationship for cultivated soils in north central Iowa. Soil Science Society of America Journal 67, 1823–1829.
Organic carbon, texture, and quantitative color measurement relationship for cultivated soils in north central Iowa.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3sXovFCksbc%3D&md5=f461274152c76a53326ca58bc8712479CAS |

Kosaka J, Honda C, Iseki A (1959) A new rapid and accurate method for the determination of carbon in soils. Soil Science and Plant Nutrition 5, 77–83.
A new rapid and accurate method for the determination of carbon in soils.Crossref | GoogleScholarGoogle Scholar |

Kramer C, Gleixner G (2008) Soil organic matter in soil depth profiles: distinct carbon preferences of microbial groups during carbon transformation. Soil Biology & Biochemistry 40, 425–433.
Soil organic matter in soil depth profiles: distinct carbon preferences of microbial groups during carbon transformation.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXhtlajs7fI&md5=210a6d91e1464707360715cca6da4c72CAS |

Krishnan P, Alexander JD, Butler BJ, Hummel JW (1980) Reflectance technique for predicting soil organic matter. Soil Science Society of America Journal 44, 1282–1285.
Reflectance technique for predicting soil organic matter.Crossref | GoogleScholarGoogle Scholar |

Lahijani P, Zainal ZA, Mohammadi M, Mohamed AR (2015) Conversion of the greenhouse gas CO2 to the fuel gas CO via the Boudouard reaction: a review. Renewable & Sustainable Energy Reviews 41, 615–632.
Conversion of the greenhouse gas CO2 to the fuel gas CO via the Boudouard reaction: a review.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXhsV2jsL%2FK&md5=5bc8ab5369efc9db3ecc272182cce7a4CAS |

Lal R, Follett RF, Stewart BA, Kimble JM (2007) Soil carbon sequestration to mitigate climate change and advance food security. Soil Science 172, 943–956.
Soil carbon sequestration to mitigate climate change and advance food security.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXhsVelsLjJ&md5=d215e60fe9c50f19adc4dc7165cc4127CAS |

LECO (2013) TruMac Series. Available at: www.leco.com/products/analytical-sciences/carbon-nitrogen-protein-sulfur/trumac-series#features (accessed 10 July 2014).

Lettens S, de Vos B, Quataert P, van Wesemael B, Muys B, van Orshoven J (2007) Variable carbon recovery of Walkley–Black analysis and implications for national soil organic carbon accounting. European Journal of Soil Science 58, 1244–1253.
Variable carbon recovery of Walkley–Black analysis and implications for national soil organic carbon accounting.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXitVWmsQ%3D%3D&md5=feab50187a1ac21ca20f199abe115bb6CAS |

MacCarthy P, Malcolm RL, Clapp CE, Bloom PR (1990) An introduction to soil humic substances. In ‘Humic substances in soil and crop sciences: Selected readings’. (Ed. P MacCarthy) pp. 1–12. (American Society of Agronomy and Soil Science Society of America: Madison, WI)

McCarty GW, Reeves JB, Reeves VB, Follett RF, Kimble JM (2002) Mid-infrared and near-infrared diffuse reflectance spectroscopy for soil carbon measurements. Soil Science Society of America Journal 66, 640–646.
Mid-infrared and near-infrared diffuse reflectance spectroscopy for soil carbon measurements.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD38XlvVCmt7g%3D&md5=96808ac6b6b89da57f67eb116752728eCAS |

Martin MZ, Mayes MA, Heal KR, Brice DJ, Wullschleger SD (2013) Investigation of laser-induced breakdown spectroscopy and multivariate analysis for differentiating inorganic and organic C in a variety of soils. Spectrochemica Acta Part B 87, 100–107.
Investigation of laser-induced breakdown spectroscopy and multivariate analysis for differentiating inorganic and organic C in a variety of soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3sXhtVahu7bF&md5=f0a3dd8579f8e2ae2b46831d6b5b8cf1CAS |

Matsuda K, Schnitzer M (1972) The permanganate oxidation of humic acids extracted from acid soils. Soil Science 114, 185–193.
The permanganate oxidation of humic acids extracted from acid soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE38XltlyrurY%3D&md5=26f997a1ab66ad808d63e852f27bfb54CAS |

Matthiessen MK, Larney FJ, Selinger LB, Olson AF (2005) Influence of loss-on-ignition temperature and heating time on ash content of compost and manure. Communications in Soil Science and Plant Analysis 36, 2561–2573.
Influence of loss-on-ignition temperature and heating time on ash content of compost and manure.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXht1agtrfJ&md5=6cd841fab3911cfc05d21280bb26a25eCAS |

Mebius LJ (1960) A rapid method for the determination of organic carbon in soil. Analytica Chimica Acta 22, 120–124.
A rapid method for the determination of organic carbon in soil.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF3cXktVamsw%3D%3D&md5=e0a211420a159c3a4178477b08e77187CAS |

Metz B, Davidson OR, Bosch PR, Dave R, Meyer LA (2007) Climate Change 2007: Working Group III: Mitigation of Climate Change (IPCC). Available at: www.ipcc.ch/publications_and_data/ar4/wg3/en/tssts-ts-8-3-mitigation-technologies.html (accessed 23 July 2014).

Morra MJ, Hall MH, Freeborn LL (1991) Carbon and nitrogen analysis of soil fractions using near-infrared reflectance spectroscopy. Soil Science Society of America Journal 55, 288–291.
Carbon and nitrogen analysis of soil fractions using near-infrared reflectance spectroscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK3MXhvVCht7k%3D&md5=748f431fee64b7815331dbb93dbb1b79CAS |

Mosier-Boss PA, Liebermann SH, Theriault GA (2002) Field demonstrations of a direct push FO-LIBS metal sensor. Environmental Science & Technology 36, 3968–3976.
Field demonstrations of a direct push FO-LIBS metal sensor.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD38XlvVOrsb4%3D&md5=f4bbaaac75ab13f688be1fe90fd1d1beCAS |

Mouazen AM, Karoui R, Deckers J, De Baerdemaeker J, Ramon H (2007a) Potential of visible and near-infrared spectroscopy to derive colour groups utilising the Munsell soil colour charts. Biosystems Engineering 97, 131–143.
Potential of visible and near-infrared spectroscopy to derive colour groups utilising the Munsell soil colour charts.Crossref | GoogleScholarGoogle Scholar |

Mouazen AM, Maleki MR, De Baerdemaeker J, Ramon H (2007b) On-line measurement of some selected soil properties using a VIS–NIR sensor. Soil & Tillage Research 93, 13–27.
On-line measurement of some selected soil properties using a VIS–NIR sensor.Crossref | GoogleScholarGoogle Scholar |

Munsell (2013) Official Site of Munsell Color. Available at: http://munsell.com/about-munsell-color/how-color-notation-works/ (accessed 23 July 2014).

Nelson DW, Sommers LE (1974) A rapid and accurate procedure for estimation of organic carbon in soils. Proceedings of the Indiana Academy of Science 84, 456–462.

Ngo P-T, Rumpel C, Doan T-T, Jouquet P (2012) The effect of earthworms on carbon storage and soil organic matter composition in tropical soil amended with compost and vermicompost. Soil Biology & Biochemistry 50, 214–220.
The effect of earthworms on carbon storage and soil organic matter composition in tropical soil amended with compost and vermicompost.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38Xntlajtr8%3D&md5=6b9cbd4681aa7e53a87543bee35083bfCAS |

Oades JM (1988) The retention of organic matter in soils. Biogeochemistry 5, 35–70.
The retention of organic matter in soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL1cXitVeksb0%3D&md5=e3673fa9c6b1a55c1c78ef568a3973f7CAS |

Olive PL (1998) The role of DNA single and double strand breaks in cell killing by ionizing radiation. Radiation Research 150, S42–S52.
The role of DNA single and double strand breaks in cell killing by ionizing radiation.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK1cXnt1Cru7s%3D&md5=395cf705072869b6b49e040890d2454eCAS | 9806608PubMed |

Olson KR, Lang JM, Ebelhar SA (2005) Soil organic carbon changes after 12 years of no-tillage and tillage of Grantsburg soils in southern Illinois. Soil & Tillage Research 81, 217–225.
Soil organic carbon changes after 12 years of no-tillage and tillage of Grantsburg soils in southern Illinois.Crossref | GoogleScholarGoogle Scholar |

Parsons A, Bodnarik J, Evans L, Floyd S, Lim L, McCanahan T, Namkung M, Nowicki S, Schweitzer J, Starr R, Trombka J (2011) Active neutron and gamma-ray instrumentation for in situ planetary science applications. Nuclear Instruments & Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment 652, 674–679.
Active neutron and gamma-ray instrumentation for in situ planetary science applications.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXhtF2ju7zI&md5=748d8645b6835b92220f7c1efe20a6d8CAS |

Randall RB, Benger M, Groocock CM (1938) The alkaline permanganate oxidation of organic substances selected for their bearing upon the chemical constitution of coal. Proceedings of the Royal Society of London. Series A 165, 432–452.
The alkaline permanganate oxidation of organic substances selected for their bearing upon the chemical constitution of coal.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaA1cXjvVOnuw%3D%3D&md5=64f0f3782bd11e7b8267e6bf244f647dCAS |

Rayment GE, Higginson FR (1992) ‘Australian laboratory handbook of soil and water chemical methods.’ (Inkata Press: Melbourne)

Rayment GE, Lyons DJ (2011) ‘Soil chemical methods – Australasia.’ (CSIRO Publishing: Melbourne)

Reeves JB (2010) Near- versus mid-infrared diffuse reflectance spectroscopy for soil analysis emphasizing carbon and laboratory versus on-site analysis: where are we and what needs to be done? Geoderma 158, 3–14.
Near- versus mid-infrared diffuse reflectance spectroscopy for soil analysis emphasizing carbon and laboratory versus on-site analysis: where are we and what needs to be done?Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXnvFWhsr0%3D&md5=5b81b7590eff94a07358016e2a21ae9cCAS |

Reeves JB, McCarty GW (2001) Quantitative analysis of agricultural soils using near infrared reflectance spectroscopy and a fibre-optic probe. Journal of Near Infrared Spectroscopy 9, 25–34.
Quantitative analysis of agricultural soils using near infrared reflectance spectroscopy and a fibre-optic probe.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3MXjvFeisL8%3D&md5=ccfe6e6626d9f5fb7f08a83a369c833fCAS |

Rozantsev VA, Shirokanov AD, Yankovskii AA (1993) Effect of the time interval between single laser pulses on the character of the laser plasma spectrum. Journal of Applied Spectroscopy 59, 797–800.
Effect of the time interval between single laser pulses on the character of the laser plasma spectrum.Crossref | GoogleScholarGoogle Scholar |

Rusak DA, Castle BC, Smith BW, Winefordner JD (1997) Fundamentals and applications of laser-induced breakdown spectroscopy. Critical Reviews in Analytical Chemistry 27, 257–290.
Fundamentals and applications of laser-induced breakdown spectroscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK1cXjsFaktQ%3D%3D&md5=d4a129142e8baec63a691bc11fe2aa7fCAS |

Sankey JB, Brown DJ, Bernard ML, Lawrence RL (2008) Comparing local vs. global visible and near-infrared (VisNIR) diffuse reflectance spectroscopy (DRS) calibrations for the prediction of soil clay, organic C and inorganic C. Geoderma 148, 149–158.
Comparing local vs. global visible and near-infrared (VisNIR) diffuse reflectance spectroscopy (DRS) calibrations for the prediction of soil clay, organic C and inorganic C.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXhsVWhtb7J&md5=a51459e76eee99df28b97e8c6b3e9e63CAS |

Schmidt A, Smernik RJ, McBeath TM (2012) Measuring organic carbon in Calcarosols: understanding the pitfalls and complications. Soil Research 50, 397–405.
Measuring organic carbon in Calcarosols: understanding the pitfalls and complications.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38Xht1Smu7nO&md5=51fa54126a681c160dcd0816e3268696CAS |

Schnitzer M, Desjardins JG (1964) Further investigations on the alkaline permanganate oxidation of organic matter extracted from a podzol Bh horizon. Canadian Journal of Soil Science 44, 272–279.
Further investigations on the alkaline permanganate oxidation of organic matter extracted from a podzol Bh horizon.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF2sXktlWqs7o%3D&md5=3d009a7f321267bc9683481fe7ca1341CAS |

Schollenberger CJ (1927) A rapid approximate method for determining soil organic matter. Soil Science 24, 65–68.
A rapid approximate method for determining soil organic matter.Crossref | GoogleScholarGoogle Scholar |

Schollenberger CJ (1945) Determination of soil organic matter. Soil Science 59, 53–56.
Determination of soil organic matter.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaH2MXht1Gjug%3D%3D&md5=8f71df6edf517c8f1cf2834eeaeb65d6CAS |

Schulte EE, Hopkins BG (1996) Estimation of soil organic matter by weight loss-on-ignition. In ‘Soil organic matter: analysis and interpretation’. (Eds FR Magdoff, MA Tabatabai, EA Hanlon) pp. 21–31. (Soil Science Society of America: Madison, WI)

Schulte EE, Kaufmann C, Peter JB (1991) The influence of sample size and heating time on soil weight loss-on-ignition. Communications in Soil Science and Plant Analysis 22, 159–168.
The influence of sample size and heating time on soil weight loss-on-ignition.Crossref | GoogleScholarGoogle Scholar |

Selige T, Bohner J, Schmidhalter U (2006) High resolution topsoil mapping using hyperspectral image and field data in multivariate regression modeling procedures. Geoderma 136, 235–244.
High resolution topsoil mapping using hyperspectral image and field data in multivariate regression modeling procedures.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28XhtlahtbvF&md5=e25413fb03a4bd26cd4b8a8c248b7cd9CAS |

Shields JA, Paul EA, St Arnaud RJ, Head WK (1968) Spectrophotometry measurement of soil color and its relationship to moisture and organic matter. Canadian Journal of Soil Science 48, 271–280.
Spectrophotometry measurement of soil color and its relationship to moisture and organic matter.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF1cXltVGgt7g%3D&md5=b9d73d576559e38523aff2d8e1fcb865CAS |

Sims JR, Haby VA (1971) Simplified colorimetric determination of soil organic matter. Soil Science 112, 137–141.
Simplified colorimetric determination of soil organic matter.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE3MXkvFOls70%3D&md5=e62e8532d3315e760f9ed2179218a068CAS |

Singh K, Murphy BW, Marchant BP (2012) Towards cost-effective estimation of soil carbon stocks at the field scale. Soil Research 50, 672–684.
Towards cost-effective estimation of soil carbon stocks at the field scale.Crossref | GoogleScholarGoogle Scholar |

Skalar (2014) Primacs series total organic carbon and total carbon analyzers. Available at: www.skalar.com/analyzers/total-organic-carbon-toc-and-total-carbon-tc-analyzers/ (accessed 9 July 2014).

Skjemstad JO, Baldock JA (2008) Soil sampling and methods of analysis. In ‘Total and organic carbon’. 2nd edn. (Eds MR Carter, EG Gregorich) pp. 225–237. (Canadian Society of Soil Science)

Skjemstad JO, Taylor JA, Smernik RJ (1999) Estimation of charcoal (char) in soils. Communications in Soil Science and Plant Analysis 30, 2283–2298.
Estimation of charcoal (char) in soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK1MXmt1GltLw%3D&md5=bb248fd5dc2c2dbd4ed98ba3af3df529CAS |

Skjemstad JO, Spouncer LR, Cowie B, Swift RS (2004) Calibration of the Rothamsted organic carbon turnover model (RothC ver. 26.3), using measurable soil organic carbon pools. Soil Research 42, 79–88.
Calibration of the Rothamsted organic carbon turnover model (RothC ver. 26.3), using measurable soil organic carbon pools.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXht1ahsbo%3D&md5=7cbbbed7b8e5eb4a3b646377f2180268CAS |

Smith T, Guild J (1932) The C.I.E. colorimetric standards and their use. Transactions of the Optical Society 33, 73–134.

Snyder JD, Trofymow JA (1984) A rapid accurate wet oxidation diffusion procedure for determining organic and inorganic carbon in plant and soil samples. Communications in Soil Science and Plant Analysis 15, 587–597.
A rapid accurate wet oxidation diffusion procedure for determining organic and inorganic carbon in plant and soil samples.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL2cXkvV2lsrw%3D&md5=c34a0662fe760f29e7dfee6ab3121493CAS |

Soon YK, Abboud S (1991) A comparison of some methods for soil organic carbon determination. Communications in Soil Science and Plant Analysis 22, 943–954.
A comparison of some methods for soil organic carbon determination.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK3MXltlCqtro%3D&md5=2c873850424107960171d5473ea4058cCAS |

Steinhardt GC, Franzmeier DP (1979) Comparison of organic matter content with soil color for silt loam soils of Indiana. Communications in Soil Science and Plant Analysis 10, 1271–1277.
Comparison of organic matter content with soil color for silt loam soils of Indiana.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE1MXlvFWqt7k%3D&md5=fe73ee16cfdd32ab90c5245665baf1c7CAS |

Stevens A, van Wesemael B, Bartholomeus H, Rosillon D, Tychon B, Ben-Dor E (2008) Laboratory, field and airborne spectroscopy for monitoring organic carbon content in agricultural soils. Geoderma 144, 395–404.
Laboratory, field and airborne spectroscopy for monitoring organic carbon content in agricultural soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXitl2jt7w%3D&md5=77c2bcc1f3046b409b63adcbd3ccfc02CAS |

Stevens A, Udelhoven T, Denis A, Tychon B, Lioy R, Hoffman L, van Wesemael B (2010) Measuring soil organic carbon in croplands at regional scale using airborne imaging spectroscopy. Geoderma 158, 32–45.
Measuring soil organic carbon in croplands at regional scale using airborne imaging spectroscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXnvFWhsro%3D&md5=454517bf138e62f61a174cee6f5aa9e5CAS |

Tabatabai MA, Bremner JM (1970) Use of the LECO automatic 70-second carbon analyzer for total carbon analysis in soils. Soil Science Society of America Journal 34, 608–610.
Use of the LECO automatic 70-second carbon analyzer for total carbon analysis in soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE3cXkslKiu7o%3D&md5=d42ff7a77bba39b89d47fdbad6a39ce9CAS |

Tam NFY, Yao MWY (1998) An accurate, simple and novel analytical method for the determination of total organic carbon in sediment. International Journal of Environmental Analytical Chemistry 72, 137–150.
An accurate, simple and novel analytical method for the determination of total organic carbon in sediment.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK1MXjsFygs7c%3D&md5=43396891cf6bd5a93d9c86f2d9955317CAS |

Tisdall JM, Oades JM (1979) Stabilization of soil aggregates by the root systems of ryegrass. Australian Journal of Soil Research 17, 429–441.
Stabilization of soil aggregates by the root systems of ryegrass.Crossref | GoogleScholarGoogle Scholar |

Tisdall JM, Oades JM (1982) Organic matter and water-stable aggregates in soils. Journal of Soil Science 33, 141–163.
Organic matter and water-stable aggregates in soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL38XlsVels7w%3D&md5=bf9735d126e7b29eacba69504c75c16cCAS |

USGS (2013) Landsat Missions Timeline. Available at: http://landsat.usgs.gov/about_mission_history.php (accessed 23 July 2014).

Velasquez E, Pelosi C, Brunet D, Grimaldi M, Martins M, Rendeiro AC, Barrios E, Lavelle P (2007) This ped is my ped: visual separation and near infrared spectra allow determination of the origins of soil macroaggregates. Pedobiologia 51, 75–87.
This ped is my ped: visual separation and near infrared spectra allow determination of the origins of soil macroaggregates.Crossref | GoogleScholarGoogle Scholar |

Viscarra Rossel RA, Webster R (2012) Predicting soil properties from the Australian soil visible–near infrared spectroscopic database. European Journal of Soil Science 63, 848–860.
Predicting soil properties from the Australian soil visible–near infrared spectroscopic database.Crossref | GoogleScholarGoogle Scholar |

Viscarra Rossel RA, Minasny B, Roudier P, McBratney AB (2006a) Color space models for soil science. Geoderma 133, 320–337.
Color space models for soil science.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28XmtlOntrs%3D&md5=72633257ec87d4388f751ad364f70f3fCAS |

Viscarra Rossel RA, Walvoort DJJ, McBratney A, Janik LJ, Skjemstad JO (2006b) Visible, near infrared, mid infrared or combined diffuse reflectance spectroscopy for simultaneous assessment of various soil properties. Geoderma 131, 59–75.
Visible, near infrared, mid infrared or combined diffuse reflectance spectroscopy for simultaneous assessment of various soil properties.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28XhtFyhsLg%3D&md5=2a0cca6f01847a9e287cba4fe7a79278CAS |

Viscarra Rossel RA, Fouad Y, Walter C (2008) Using a digital camera to measure soil organic carbon and iron contents. Biosystems Engineering 100, 149–159.
Using a digital camera to measure soil organic carbon and iron contents.Crossref | GoogleScholarGoogle Scholar |

Walkley A (1935) An examination of methods for determining organic carbon and nitrogen in soils. The Journal of Agricultural Science 25, 598–609.
An examination of methods for determining organic carbon and nitrogen in soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaA28XhsVCksw%3D%3D&md5=758b8ccb1b8bcea6d876b47af9c2d906CAS |

Walkley A (1947) A critical examination of a rapid method for determining organic carbon in soils: effect of variations in digestion conditions and of inorganic soil constituents. Soil Science 63, 251–264.
A critical examination of a rapid method for determining organic carbon in soils: effect of variations in digestion conditions and of inorganic soil constituents.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaH2sXivVWqtQ%3D%3D&md5=881cb9190d8b36d8e66709ab4d4a3aecCAS |

Walkley A, Armstrong Black I (1934) An examination of the Degtjareff method for determining soil organic matter, and a proposed modification of the chromic acid titration. Soil Science 37, 29–38.
An examination of the Degtjareff method for determining soil organic matter, and a proposed modification of the chromic acid titration.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaA2cXitlGmug%3D%3D&md5=6d1431184c84f58bc8b971881a32f2c1CAS |

Weil RR, Islam KR, Stine MA, Gruver JB, Samson-Liebig SE (2003) Estimating active carbon for soil quality assessment: a simplified method for laboratory and field use. American Journal of Alternative Agriculture 18, 3–17.
Estimating active carbon for soil quality assessment: a simplified method for laboratory and field use.Crossref | GoogleScholarGoogle Scholar |

Wetzel DL (1983) Near-infrared reflectance analysis. Analytical Chemistry 55, 1165A–1176A.
Near-infrared reflectance analysis.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL3sXlsFWis7Y%3D&md5=5cdbdece08a758059fbb38bf28336887CAS |

Wielopolski L, Hendrey G, Johnsen KH, Mitra S (2008) Nondestructive system for analyzing carbon in the soil. Soil Science Society of America Journal 72, 1269–1277.
Nondestructive system for analyzing carbon in the soil.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXhtV2itrfM&md5=b514b35ea6234f4db251db16369e0d73CAS |

Wielopolski L, Yanai RD, Levine CR, Mitra S, Vadeboncoeur A (2010) Rapid, non-destructive carbon analysis of forest soils using neutron-induced gamma-ray spectroscopy. Forest Ecology and Management 260, 1132–1137.
Rapid, non-destructive carbon analysis of forest soils using neutron-induced gamma-ray spectroscopy.Crossref | GoogleScholarGoogle Scholar |

Wielopolski L, Chatterjee A, Mitra S, Lal R (2011) In situ determination of soil carbon pool by inelastic neutron scattering: comparison with dry combustion. Geoderma 160, 394–399.
In situ determination of soil carbon pool by inelastic neutron scattering: comparison with dry combustion.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXit1KqsQ%3D%3D&md5=83b9b138a707423be8849238e7692014CAS |

Wright WD (1929) A re-determination of the trichromatic coefficients of the spectral colours. Transactions of the Optical Society 30, 141–164.
A re-determination of the trichromatic coefficients of the spectral colours.Crossref | GoogleScholarGoogle Scholar |

Zimmermann M, Liefeld J, Schmidt MWI, Smith P, Fuhrer J (2007) Measured soil organic matter fractions can be related to pools in the RothC model. European Journal of Soil Science 58, 658–667.
Measured soil organic matter fractions can be related to pools in the RothC model.Crossref | GoogleScholarGoogle Scholar |