Phosphorus Soil Tests for Nutrient Recommendations: Comparisons of Routine and Soil Health Testing Methods
2022
- Department of Soil Science, UW Madison
Project Media
Soil phosphorus (P) tests used for crop nutrient recommendations should be correlated to crop yield response and calibrated to identify interpretation classes of responsiveness. Common soil P tests recommended for the U.S. north-central region have been correlated to crop yield response, and include the Bray-1, Mehlich-3, and Olsen tests. Which test is used more predominately in a state is a function of the recommendation systems in place, chemical reactions between soil constituents and the extracting solutions, and its overall intended use. Also important is the ability to use a test to extract and measure additional elements, which is the case for the Mehlich-3 test in Iowa or Bray-1 test in Wisconsin.