More Changes to the Tri-State Fertilizer Recommendations

The finalized document for the latest revision of the Tri-State Fertilizers recommendations for Indiana, Ohio and Michigan has been released. Various aspects of the revised recommendations have been released in small segments over the past 2 years. The summaries of the changes/updates to the recommendations prior to the release of the final document have noted that soil pH and liming recommendations would not change from the previous version released in 1995. Upon review of the final document, notable changes have been made to the university recommendations for soil pH management and lime application rates.

• Now there are a set of lime recommendations for Ohio and separate set for Indiana and Michigan.
• Lime rate recommendations for mineral soils, those soils with less than 20% organic matter and a cation exchange capacity of greater than 5 meq/100cc, have changed.
  • Indiana and Michigan lime rate recommendations have different values in the equations to calculate lime rates and rates have been increased by 10-20%.
  • The Ohio lime rate recommendations for mineral soils have new equations to calculate lime rates and rates have been decreased by 30-35%.
• Organic soil lime rates, for those soils with greater than 20% organic matter, have changed.
  • Michigan and Indiana lime rates have increased 25-100%. In the previous version of the recommendations there was one equation for organic soils, now there are three.
  • Ohio lime rates have decreased 30-35% and the publication does not offer equations to calculate rates.
• Weakly buffered soils were not specially defined in the previous recommendation document, but often classified through interpretation as soils with cation exchange capacities of 6 meq/100cc or less. The revised recommendation set reference to weakly buffered soils as those with a cation exchange capacity of less than 5 meq/100cc . The adoption of Mehlich 3 as the extractant used to determine potassium, calcium and magnesium levels will led to a 15-18% increase in cation exchange capacity by summation values reported on soil tests.

The final release the “Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat, and Alfalfa” can be found at https://extensionpubs.osu.edu/search.php?search_query=974&section=product.