fertilizer

Minimum levels for sustainable nutrition—MLSN—is a modern method for interpreting soil tests for turfgrass.

This email inquiry arrived recently: “Hi Micah, looking at the MLSN guidelines and our recent test results, all our levels are above what’s required. Does this mean, we only need to apply N until levels come down?

This is about the quantity of nutrients in reserve, the quantity of nutrients in the soil that the grass doesn’t use, when one keeps the soil nutrients at or above the MLSN values.

This article about MLSN was published in Greenkeeper International in 2018. I suppose it’s one many of you have never seen. My title for this was “Making Sense of Turf Nutrition with MLSN”, although when published it was shortened simply to “Turf Nutrition.

It is a common practice of commercial fertilizer companies to mix fertilizing materials in different proportions with the view to selling them for special conditions. These ready-mixed fertilizers are extensively advertised … and the opinion seems to prevail in the minds of many that they are just what is required.

A lot of turfgrass nutrition research gets done with fixed rates of fertilizer applied on a fixed time schedule. It always seemed normal for me to fertilize this way. Here are a few examples.

I talked with Frank Rossi today on the ATC Doublecut. You can watch or listen to the show at the links. We discussed potassium (K) fertilizer, and why there are still recommendations for so much more K than the grass can use.

When I make nutrient recommendations, I recommend a quantity of each element that ensures the grass can get all of that nutrient that the grass can use. I also make the recommendation with a thought about the soil.

One of the many ways to learn is through conversations with industry veterans. Their wisdom about how turf is managed now, and how it was managed in the past, can be invaluable.

The usual way of thinking about soil nutrients and turf quality is something like this: when the amount of a soil nutrient is low, the turf quality won’t be as good as it would be if that nutrient were more abundant in the soil.