Protocol for Biocarbonate extraction of inorganic phosphate from agricultural soils
DCA rapport, nr. 102, 2017
Af Gitte H. Rubæk og Kristian Kristensen
The Olsen phosphorus (P) soil test, known in Denmark as “Ptallet” or “fosfortallet”, has been used for decades for P fertilizer recommendations. Today it is also used to device legislative thresholds for application of P to farmers fields. It is therefore unfortunate that the test results of this method vary significantly and systematically between laboratories and over time. Consequently, there has been several initiatives to document this and suggest ways to increase the robustness of the analysis. This report is the outcome of a project commissioned by the Environmental Protection Agency to quantify the importance of key elements in the Danish protocol for the Olsen P analysis and formulate a final concise protocol suitable for implementation in commercial soil laboratories. An advisory board consisting of representatives from three soil P testing commercial soil laboratories, SEGES and experts from Copenhagen and Aarhus Universities supervised this project. The results of the tests, recommendations of the advisory board and the final version of the protocol for the Olsen P analysis is included in this report.