Adoption of Mehlich 3 Soil Test Data

ALGL has need utilizing the Mehlich 3 (M3) universal soil extractant since 1991, however most of the data sent to customer over the past 30 years has been regressed and reported as Bray P-1, ammonium acetate, hydrochloric acid, and how water boron equivalents. This has been due to most interpretive fertilizer application recommendation sets have historically been in these traditional extractions. These traditional lab methods are commonly referred to as “North Central Region” (NCR) methods. With the revision of university-based fertilizer recommendations in Indiana, Ohio, and Michigan we are seeing an increase in customers opting to receive soil test data in the raw M3 values.

Below are some suggestions to help make the transition to M3 easier.

  • Make the conversion at a transitional time of the year, not in the middle of a fertility decision cycle. For example if you collect soil samples in the spring, make recommendations and review with producers in the summer and apply in the fall. A good time to make a clean transition to M3 would be in the winter prior to the collection of spring soil samples.
  • Don’t convert a field in the middle of a sampling cycle. If you sample every 4 years, wait until the next sampling cycle to convert a field. While it may seem best to change all fields at one time, changing within a sampling cycle can create more confusion. A clear transition time (month and year) is useful to verify what method a given field’s data is in by comparing the sample collection date to the M3 transition date.
  • Share a mailer or meeting with growers as to when the change is made and how M3 data compared to past NCR data. Your ALGL agronomist has education materials that can be used to help in this process.
  • Make sure to have fertility equations for both data types in your GIS software. Be sure to develop a process to ensure the correct equation is applied to the correct data, a clear transition date as mentioned above can help with this.
  • Be sure to communicate with your GIS software provider, most software need to identify if the data is M3 before the data is imported. Our software company can walk you through the needed changes.
  • Contact the lab before the transition is to take place. ALGL will need to adjust your account and possibly the GIS data export process to ensure that your data flow is not interrupted.
  • While it may seem best to report both data values for a period of time, or to convert past data, this has proven problematic. It is best to make a defined transition at a preset and strategic time. For one sampling cycle there will be two forms of data active, the key to managing this period of data is to be able to clearly identity the method reflected in the data.

ALGL will only change data export form upon request by the customer. If you have any questions in regard to changing to M3 data, or if we can be of assistance in the transition, please reach out to your ALGL regional agronomist.

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