To assess the quality of a soil it is necessary to know its nutrients. For example, it is necessary that the level of bio-available ions is known as a deficiency might negatively affect plant growth. One of the most important ions is potassium which is directly absorbed in its ionic form by plants roots. It is an essential nutrient and required for proper growth and reproduction.

One commonly used method to assess the K content is the extraction of phosphorous and potassium from soil with an acidic, to pH 4.1 buffered solution of calcium acetate, calcium lactate, and glacial acetic acid. This test is called calcium acetate lactate test (CAL-test). Commonly, the extract is analyzed by flame photometric method. In this application note we present a fast and inexpensive alternative using the potassium ion selective electrode.

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