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Agronomic Services — Soil Test Methodologies


An extractant developed to measure nutrient content of acidic soils, which are prevalent across the southeastern United States, Africa and Latin America. Adopted in 1953, this method is now widely used throughout these areas.


An extractant developed to measure amounts of major nutrients and micronutrients in soil. It is effective on soils with a wide range of physical and chemical properties. Adopted in 1981, this method has reduced analytical costs by replacing dual extraction methods. It has been adopted by a number of national and international laboratories. More information.

  • Reference: Mehlich A. 1984. Mehlich-3 soil test extractant: a modification of Mehlich-2 extractant. Commun Soil Sci Plant Anal 15(12):1409–16.
  • Composition: (0.2N CH3COOH + 0.25N NH4NO3 + 0.013N HNO3 + 0.015N NH4F + 0.001M EDTA)

Mehlich-buffer acidity

A buffer method developed to measure the content of soil acidity for determining lime requirement. Adopted in 1976, the method measures both hydrogen and aluminum. More information.

  • Reference:
    Mehlich A, Bowling SS, Hatfield AL. 1976. Buffer pH acidity in relation to nature of soil acidity and expression of lime requirement. Commun Soil Sci Plant Anal 7(3):253–63.

Humic matter methodology

A method adopted in 1982 to distinguish between soil classes for making more appropriate lime recommendations and for determining herbicide application rates.

  • Reference:
    Mehlich A. 1984. Photometric determination of humic matter in soils, a proposed method. Commun Soil Sci Plant Anal 15(12):1417–22.

Volumetric soil testing

A method that uses a set volume for measuring and calculating the nutrient content of soils. Results can be expressed as kg/ha, lb/acre, mg/dm³ and cmole/100 cm³.

  • References:
    Mehlich A. 1972. Uniformity of soil test results: a case for calculating results on a volume basis. Commun Soil Sci Plant Anal 3(5):417–24.

    Mehlich A. 1973. Uniformity of soil test results as influenced by volume weight. Commun Soil Sci Plant Anal 4(6):475–86.

    Tucker MR. 1984. Volumetric measures for routine soil testing. Commun Soil Sci Plant Anal 15(7):833–40.

Last Update April 24, 2013



NCDA&CS Agronomic Services Division, Colleen M. Hudak-Wise, Ph.D., Director
Mailing Address: 1040 Mail Service Center, Raleigh NC 27699-1040
Physical Address: 4300 Reedy Creek Road, Raleigh NC 27607-6465
Phone: (919) 733-2655; FAX: (919) 733-2837