Release of New Tri-State Recommendations

The new Tri-State Fertilizer Recommendations for Indiana, Michigan and Ohio have been released and more information can be found at There are a couple of key changes.  

  • The adoption of the MRTN (Maximum Return to Nitrogen) model that takes both grain and nitrogen price into consideration when determining corn N rates.
  • The nitrogen rates for wheat have been updated to reflect recent field trial data.
  • Phosphorus and potassium recommendation will now be based on Mehlich-3 (M3) data values.
  • Phosphorus and potassium recommendation framework has been altered to remove the drawdown portion of the recommendation set and made buildup rates above crop removal optional to reflect fertility management on rented land.
  • The phosphorus critical level has been set at 20 ppm M3 for corn and bean rotation, 30 ppm M3 when wheat or alfalfa are included in the rotation. This keeps the critical level effectively unchanged.
  • The potassium critical level has been simplified to 100 ppm M3 for sandy soils with a CEC of 5 meq/100g or less and 120 ppm for soils with a CEC greater than 5. For soils with a CEC of 5 meq/100g or less the maintenance range is 100 ppm to 130 ppm, the maintenance range for those soils with a CEC greater than 5 meq/100g widens from 120 ppm to 170 ppm.  
  • The crop removal rates for phosphorus and potassium have been updated to reflect current data.
  • Lime recommendations remain the same.

ALGL has been using M3 as a standard method since 1991 and converting the data to equivalent Bray-P and ammonium acetate K values for reporting. Both values have been available and will continue to be available. Rather than making any wholesale changes to data formats, we will be only converting customer data to M3 upon request. If you have any questions on how the change to M3 will impact your data, or need any additional question feel free to contact the lab or your ALGL agronomy representative.    

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