Soil Health Testing: Calibration and Correlation Research Needed

AGVISE laboratories has offered new soil health testing methods for the past two years. The Haney test and the Solvita test are examples of soil health tests now being evaluated. There has been a lot of interest in these tests as some NRCS programs include these tests as one of the enhancements farmers can choose to do when they participate in the programs.

As farmers get test results from these new soil health test methods, they are asking how they can use these results to modify their fertilizer guidelines. The problem is that these new tests do not have the needed research from this region to make fertilizer recommendations at this time. It is very important that any new soil testing method have research that shows it is correlated to crop uptake or yield. A soil test is well correlated if a low test predicts a low yield for a crop and a high test result predicts a high yield. If the research shows a strong relationship then that test is well correlated with crop response. Once a test is found to be well correlated with crop yield, you need calibration research. Calibration research tells you if the new soil test can predict how much of a nutrient is needed to meet the crops need at low test levels and at high test levels.

At this time there is some research at the University of Minnesota evaluating the Haney tests methods. A recent publication from the U of M discusses the new Haney soil health method and compares it to the accepted soil test methods which have extensive correlation and calibration research in this region. The conclusion they came to is the Haney test needs to have correlation and calibration research in this region to be of value to farmers. Since the Haney test does not have this research behind yet, they recommend that farmers still do regular soil testing to get their fertilizer recommendations. Sometime in the future, after the research has been done on these new tests, they may be useful for farmers in this region. On September 26 there was a blog from the University of Minnesota titled: Should soil health test results be used when determining fertilizer needs in Minnesota?

This research compares the fertilizer recommendations based on accepted soil testing methods to the Haney test methods. To view this blog and the research comparing the N, P, and K recommendations for accredited methods and the Haney test, go to the AGVISE website, click this link to view the PDF.