Soil analyses

Determination of plant-available phosphorus in the soil (“Pt”): Revised and substantiated methods protocol for Denmark - established in collaboration with AGROLAB Agrar und Umwelt GmbH in DE-Sarstedt.


In Denmark, the revised version of the procedural description on Determination of plant-available phosphorous in the soil was published in August 2017.


This procedural description is mandatory from September 2017. The contracting entity of this document was the Danish Ministry of Environment and Food. The work was performed and published by Gitte Holton Rubæck and Kristian Kristensen of the DCA – Danish Centre for Food and Agriculture at the University of Aarhus. The objective was to itemise the individual process steps in such detail that variations and deviations among measuring laboratories and thus variation of measured values are minimised. This was considered necessary since the process does not achieve thermo-dynamic equilibrium within the short period of 30 minutes during extraction.

The basis of the methods protocol is the P-Olson method

The described procedure is based on what is known as the P-Olson method, taking into account experimental examinations and practical experience, as well as, a large number of real measured values and their statistical evaluation. The entire experimental part of the project was performed at AGROLAB Agrar und Umwelt GmbH (Maria Kreimeyer, Dr. Markus Rupprecht).


The decision in favour of AGROLAB was taken on the basis of 3 criteria. AGROLAB Sarstedt draws on considerable experience with this method through analysis of approx. 70,000 samples from Denmark per year. Moreover, AGROLAB was capable of defining and testing the technical process requirements for routine measurement analysis. At the same time, AGROLAB Sarstedt has very extensive experience in quality management and quality assurance of the process, which could be clearly and impressively demonstrated by their successful participation in the long-term round robin test BIPA in France.


In the new binding methods protocol, centrifugation is also possible for phase separation in addition to filtration. With filtration, it must be ensured that this step is performed directly after to extraction and that the suspension is not shaken again.


AGROLAB Agrar und Umwelt GmbH is a scientific laboratory with great professional competence for providing fast and high-quality analysis at cost-effective prices. The accredited laboratory provides analysis of agricultural soil samples for Denmark; now also as per the modified methods protocol for “Pt”.

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