I really enjoyed listening to John Kaminski on season 2 episode 3 of the Talking Greenkeeper. It was fascinating to hear how the new edition of Turfgrass Management by Turgeon and Kaminski came together.
When they were discussing the book, host Joe Gulotti asked about MLSN, and John answered that MLSN is not mentioned in the book. I appreciate his comments that “I wanted to include it” and MLSN will “definitely make it into the next edition.”
You can listen (starting around minute 42:00) for the full discussion of why MLSN is not in the book. It revolves around the same trope I’ve heard many times over the years—research behind soil test interpretations for turfgrass, and peer-review of fertilizer recommendations based on soil tests.
Existing soil test interpretation and fertilizer recommendations for turfgrass are poorly researched and are not peer reviewed. If someone doesn’t like the MLSN approach, I’d love to hear a new objection, because this one doesn’t hold water.
Here are some quotes about turfgrass fertilizer recommendations based on soil tests.
“Unfortunately, turfgrass recommendations appear to be based on research done with other crops, such as forages, results from turfgrass fertility studies not designed to relate to soil testing, and the best judgment of the agronomist making the recommendations.”
“In some cases, turfgrasses have been placed in a ‘high’ P and K requirement category … This decision was based on economics, not agronomics. The cost of fertilization was not considered of primary importance for turf.”
“Ranges for various nutrients are based on the past 60 years of fertility studies, particularly on forages, agronomic and horticultural crops, with adjustments made to fit perennial turfgrasses based on studies and the judgment of experienced university turfgrass scientists.”
“Calibration of … soil P with turfgrass growth and subsequent P fertilizer recommendations is scant … Many current recommendations for P fertilizer for turfgrasses are based on forage- or field-crop calibration data.”
“Relationships between extracted soil K, K fertilization rates, and turfgrass response needs additional study. Such work is especially missing for the sand-based systems in which many turfgrasses are managed.”
This idea that conventional recommendations have been extensively tested and peer-reviewed? That’s not the case at all.
MLSN might be a particularly bad way to make fertilizer recommendations, but that assessment should be made based on something other than whether it is peer-reviewed. Remember, any recommendations made by a method other than MLSN are not peer-reviewed either.
For more about this, one could read just about anything about MLSN. I’ll highlight these four:
That’s not the way it is supposed to work: GCSAA survey respondents who used soil testing as a best management practice “to reduce reliance on fertilizers” ended up applying more fertilizer than those who did not soil test.
Turfgrass fertiliser recommendations with or without soil tests: a summary with slides and a screencast of my keynote presentation at the European Turfgrass Society conference in Manchester last year.
The 9th MLSN newsletter: I address the issue of MLSN vs conventional guidelines and work through a few calculations for comparison.
Turfgrass nutrient guidelines, peer review, and potassium: the most extensive discussion I’ve made of this topic, from all the way back in 2014.