IPI International Potash Institute
IPI International Potash Institute

IPI K Centre - Measurement and Assessment of Soil Potassium

IPI K Centre - Measurement and Assessment of Soil Potassium

Soils have to be fertile to be productive, whether that means producing forest, grassland or agricultural crops. Fertile soil has the ability to hold reserves of many available essential plant nutrients, including potassium. This nutrient retention depends on the clay and organic matter in soil; potassium does not leach except to some extent from very sandy soils. The reserve of potassium provides a secure store which is available to the crop as it grows.

Soil tests are indispensable to monitor the soil fertility status. Testing soil for its content of plant available nutrients has been common practice for many decades. The basic principle to estimate the availability of K is to replace K from the exchange sites with an excess of another cation such as NH4 as ammonium acetate or nitrate, or with calcium (Ca) as calcium lactate or chloride. The soil K determined by this method is the so-called exchangeable K (Kex), or "readily available" soil K. Less frequently used methods are soil extraction with diluted HCl, with resins or with the help of a low electrical voltage in the Electro Ultra Filtration (EUF) method. A review of the different agents for extraction of soil K is given in the IPI Research Topics No. 4 by MUTSCHER (1995)


Potassium - a Nutrient Essential for Life
Published by IPI, 18 pages, revised 2014
Potassium Dynamics in the Soil
a set of 15 colour slides with explanations (reprinted in a small folder)
Slide Sets
IPI-Research Topics
No. 5 : Potassium in the Soil/Plant Root System
66 pages. Extracted from: Proceedings of the 11th Congress of the International Potash Institute p. 43-108 (1978)
IPI-Research Topics

Papers and presentations

Potassium Response in Vertisols in Long-Term Fertilizer Experiment
Author: Singh, M., and R.H. Wanjari
Event: e-ifc 37
Documents: PaperDownload paper (pdf 686 kB)
30 Jun 2014
Potassium Dynamics in Soil Under Different Cropping Systems and Nutrient Management Practices
Author: Ingrid Öborn
Event: IPI-OUAT-IPNI International Symposium 2009: Potassium Role and Benefits in Improving Nutrient Management for Food Production, Quality and Reduced Environmental Damages, Bhubaneswar, Orissa, India
Documents: Presentation (pdf 746 kB)
05-07 Nov 2009

Scientific abstracts

Potassium Buffering Characteristics of Three Soils Low in Exchangeable Potassium
Wang, Jim J.; Harrell, Dustin L.; Bell, Paul F.
Soil Sci. Soc. Am. J. 68:654-661 (2004)
Kinetics of Nonexchangeable-Potassium Release and Plant Response in Some Calcareous Soils
Jalali M.; M. Zarabi.
J. Plant Nutr. Soil Sci. 169(2):196-204 (2006)
Mineralogical Budgeting of Potassium in Soil: A Basis for Understanding Standard Measures of Reserve Potassium
Andrist-Rangel,Y.; Simonsson,M.; Andersson,S.; Öborn,I.; Hillier,S.
J. Plant Nutr. Soil Sci. 169(5):605-616 (2006)
Long-Term Fertilizer Experiment Network in China: Crop Yields and Soil Nutrient Trends
Zhao, B.q., X.y. Li, X.p. Li, X.j. Shi, S.m. Huang, B.r. Wang, P. Zhu, X.y. Yang, H. Liu, Y. Chen, P. Poulton, D. Powlson, A. Todd, and R. Payne
Agron. J. 102:216-230 (2010)
Acid-extractable potassium in agricultural soils: Source minerals assessed by differential and quantitative X-ray diffraction
Ylva Andrist-Rangel, Magnus Simonsson, Ingrid Öborn, Stephen Hillier
J. Plant Nutr. Soil Sci. 176(3):407-419
Analytical Studies of the CO2 Soil Test for P and K Fertilization
Stünzi, H.
Recherche Agronomique Suisse 2(1):4-11, 2011

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