MLSN for leaf tissue

This inquiry came by email under the heading of “MLSN for leaf tissue.”

Dear Micah, hope you are fine, it has been a while since we talked last. I must say that I have seen quite a lot of analyses of turf soil with good characteristics and fertilizer levels close to your MLSN.

Have you done anything similar with leaf tissue?

I replied,

Glad to hear that. MLSN for soils is meant to be a method for interpreting soil test results to make fertilizer recommendations. MLSN is an analysis of what is normal in soils that produce good turf. So I expect that the turf will perform well when soil nutrient levels remain above those MLSN minimums.

About leaf tissue, no, I haven’t. I discussed why not in this blog post, particularly in the fourth point describing my conversation with Frank Rossi at the 2016 Ryder Cup.

Tissue testing for turfgrass: four reasons I don’t like making nutrient management decisions based on what’s in the leaves

Here’s the big difference.

With soil testing, one is measuring what is in the soil but not yet in the plant. One can make fertilizer recommendations based on that, recognizing that grass requires some supply of nutrients based on how much it can grow at a particular location, and that those nutrients either have to come from the soil or from fertilizer.

With leaf tissue, the same logic doesn’t work. One could do an analysis similar to the MLSN analysis of soils, to find the normal levels of nutrients in leaf tissue. Now what we have is a measure of what is in the plant already. That’s interesting from a research perspective. But the grass doesn’t get nutrients from the tissue — grass gets nutrients from the soil or from fertilizer. To make a fertilizer recommendation, the tissue data either have to be highly correlated with the soil nutrient levels, but they are not, or the tissue data have to be correlated with turfgrass quality, which again they are not. Thus, tissue data for turfgrass don’t work nearly so well as a way to make fertilizer recommendations.