SOIL TESTING METHODS

  • Total Exchange Capacity (TEC by summation)

    Ross, D. 1995. Recommended soil tests for determining exchange capacity. p. 62-69 In J.T. Sims and A. Wolf (eds.) Recommended soil testing procedures for the northeastern United States. Northeastern Regional Bulletin #493. Ag Experiment Station, University of Delaware, Newark, DE.

  • pH (1:1 in H2O)

    McLean, E.O. 1982. Soil pH and lime requirement. p. 199-223. In A.L. Page et al. (ed.) Methods of soil analysis, part 2. Agronomy Monogr. 9, 2nd ed. ASA and SSSA, Madison, WI.

  • SMP/Sikora Buffer pH

    Shoemaker, H.E., E.O. McLean, and P.F. Pratt. 1961. Buffer methods for determining lime requirements of soils with appreciable amounts of extractable aluminum. Soil Sci. Soc. Am. Proc. 25:274-277.

    Sikora, F. 2006. A buffer that mimics the SMP buffer for determining lime requirement of soil. Soil Sci. Soc. Am. J. 70:474-486.

  • Organic Matter (Loss on Ignition at 360 degrees C)

    Schulte, E.E., and B.G. Hopkins. 1996. Estimation of soil organic matter by weight Loss-OnIgnition. p. 21-32. In: Soil organic matter: Analysis and interpretation. (ed.) F.R. Magdoff, M.A. Tabatabai, and E.A. Hanlon, Jr. Special publication No. 46. Soil Sci. Soc. Am. Madison, WI.

  • Estimated Nitrogen Release

    This number is a computed estimate of the nitrogen that may be released annually through organic matter decomposition. The calculation is based on the loss on ignition method previously listed.

  • Mehlich III Extractable S, Ca, Mg, K, Na, B, Fe, Mn, Cu, Zn, Al, and P

    Mehlich, A. 1984. Mehlich-3 soil test extractant: A modification of Mehlich-2 extractant. Commun. Soil Sci. Plant Anal. 15:1409-1416.

  • Inorganic Nitrogen (1 N KCl cadmium reduction)

    Dahnke, W.C. 1990. Testing soils for available nitrogen. p. 120-140. In R.L. Westerman (ed.) Soil testing and plant analysis. Soil Sci. Soc. Am. Book Series 3, ASA, Madison, WI.

  • Total Carbon and Nitrogen (Combustion)

    Nelson, D.W., and L.E. Sommers. 1996. Total carbon, organic carbon and organic matter. p. 961- 1010. In J.M. Bartels et al. (ed.) Methods of soil analysis: Part 3 Chemical methods. (3rd ed.) ASA and SSSA Book Series 5, Madison, WI.


    McGeehan, S.L., and D.V. Naylor. 1988. Automated instrumental analysis of carbon and nitrogen in plant and soil samples. Commun. Soil Sci. Plant Anal. 19:493-505.

  • Soil Texture: Determination of Sand, Silt, and Clay

    Hydrometer Method. ASTM D422, 2002.

  • Bray I P

    Bray, H.R., and L.T. Kurtz. 1945. Determination of total, organic, and available forms of phosphorus in soils. Soil Science 59:39-45.

  • Bray II P

    Bray, H.R., and L.T. Kurtz. 1945. Determination of total, organic, and available forms of phosphorus in soils. Soil Science 59:39-45.

  • Olsen P

    Olsen, S.R. and L.E. Sommers. 1982. Phosphorus. p. 403-430. In A.L. Page et al. (eds.) Methods of soil analysis, part 2. Agron. Monogr. 9. 2nd ed. ASA and SSSA, Madison, WI.

  • Electrical Conductivity-Soluble Salts (1:2)

    Soil, Plant, and Water Reference Methods for the Western Regions S – 2.10, 2003.

  • Saturated Paste Extract for pH, bicarbonate, nitrate, salts, chloride, cations, and minor nutrients

    Soil, Plant, and Water Reference Methods for the Western Regions S – 1.10, 1.30, 1.80, 1.20, 1.40, 1.50, 1.60, 2003.

  • Mineralization Nitrogen

    Dahnke, W.C. 1990. Testing soils for available nitrogen. p. 120-140. In R.L. Westerman (ed.) Soil testing and plant analysis. Soil Sci. Soc. Am. Book Series 3, ASA, Madison, WI.

  • Ammonium Acetate extractable cations (adjusted to a pH of 8.1)

    Suarez, D.L. 1996. Beryllium, Magnesium, Calcium, Strontium, and Barium. p. 575-602. In D.L. Sparks (ed.) Methods of soil analysis Part 3: Chemical methods. Soil Sci. Soc. Am. Book Series 5, ASA, Madison, WI.

  • DTPA extractable Zn, Mn, Fe, and Cu

    Linsay, W.L., and W.A. Norvell. 1978. Development of a DTPA soil test for zinc, iron, manganese, and copper. Soil Sci. Soc. Am. J. 42:421-428.


    All soils for standard packages are air-dried and ground to pass a 2-mm sieve.

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Note:Most Geotech testing is A2LA accredited. Therefore, the reference methods are listed on the cover sheet of the reports.


The majority of the below methods are also referenced in either:


Soil, Plant, and Water Reference Methods for the Western Region. 2003. R.G. Gavlak, D.A. Horneck, R.O. Miller, and J. Kotuby-Amacher. 2nd edition. WREP-125.


Brown, J. R. (ed.). 1998. Recommended Chemical Soil Test Procedures for the North Central Region. North Central Regional Research Publication No. 221. Missouri Agricultural Experiment Station SB 1001. Columbia, MO.


Compost Manure Methods

Water Methods

Plant Methods

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