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Agronomic Services

Crop Fertilization Based on North Carolina Soil Tests
Dr. Adolf Mehlich (1902–1983)

Dr. Adolf Mehlich served the North Carolina Department of Agriculture as a consultant in soil test methodology in 1953 and again from 1970 until his death in 1983. His life was dedicated to understanding the chemical, mineralogical, physical and microbiological characteristics of soils.

Dr. Mehlich's insight into the interaction of soil characteristics and plant nutrition was keen. He developed a volumetric method for testing, calculating and expressing soil test results on a field basis. He authored or co-authored over 70 journal articles and six chapters in books. He advised many students and was an active consultant to his peers. Dr. Mehlich received the award of "Fellow" from the American Society of Agronomy and the Soil Science Society of America in 1982. His contributions to soil science and their influence on plant nutrition have gained international renown.

Several solutions used by soil test laboratories to extract nutrients bear Dr. Mehlich's name:

  • Mehlich-1
    COMPOSITION: 0.05N HCl + 0.025N H2SO4
    USAGE: 25 cm³ extractant per 5 cm³ soil
    REFERENCE: (Mehlich, 1953)

  • Mehlich-2
    COMPOSITION: 0.2N CH3COOH + 0.015N NH4F + 0.2N NH4Cl + 0.012N HCl
    USAGE: 25 cm³ extractant per 2.5 cm³ soil
    REFERENCE: (Mehlich, 1978)

  • Mehlich-3
    COMPOSITION: 0.2N CH3COOH + 0.25N NH4NO3 + 0.013N HNO3 + 0.015N NH4F + 0.001M EDTA
    USAGE: 25 cm³ extractant per 2.5 cm³ soil
    REFERENCE: (Mehlich, 1984)

The Mehlich-1 extractant is used by laboratories across the southeastern United States and in several Latin American countries. The Mehlich-3, introduced in 1984, extracts major nutrients, as well as micronutrients, from soils with a wide range of chemical and physical properties. This extractant has been used by many state and private laboratories worldwide, including the NCDA&CS Agronomic Division laboratory.

Dr. Mehlich also developed methods for measuring soil acidity and humic matter (Mehlich, 1976, 1984). These methods are still being used by the NCDA&CS Agronomic Division laboratory. Dr. Mehlich's efforts have enhanced our capability to measure the nutrient content of soils as well as the availability of nutrients to crops under diverse soil conditions. These contributions enable soil testing laboratories to make more precise lime and fertilizer recommendations. As a result, they foster economic yields.


Mehlich A. 1953. Determination of P, Ca, Mg, K, Na, NH4. Raleigh (NC): North Carolina Department of Agriculture, Agronomic Division. Soil Testing Division Publication No. 1-53.

Mehlich A. 1976. New buffer pH method for rapid estimation of exchangeable acidity and lime requirement of soils. Commun Soil Sci Plant Anal 7(7):636-52.

Mehlich A. 1978. New extractant for soil test evaluation of phosphorus, potassium, magnesium, calcium, sodium, manganese and zinc. Commun Soil Sci Plant Anal 9(6):477-92.

Mehlich A. 1984. Mehlich-3 soil test extractant: a modification of Mehlich-2 extractant. Commun Soil Sci Plant Anal 15(12):1409-16.

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

return icon.Hardy DH, Tucker MR, Stokes CE. 2014. Crop fertilization based on North Carolina soil tests. Raleigh (NC): North Carolina Department of Agriculture and Consumer Services, Agronomic Division. Circular No. 1.

Last Update January 10, 2014


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

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