5 examples of Goodhart's law in turfgrass management

When a measure becomes a target, it ceases to be a good measure. That’s a generalization of Goodhart’s law. I’m an advocate of measuring some surface performance, plant, and soil parameters.

MLSN and salinity

When this question arrived, I thought I could respond by showing a blog post I’d written in the past with the answer. “What kind of adjustments would you recommend to do when trying to use the MLSN on a Calcareous sand green profile and irrigation with water saline water with 1500 ppm and Pure Dynasty Sea Shore Paspalum and pH 8?

Before your next calcium app, read this

The normal range of calcium (Ca) in irrigation water is 20 to 60 ppm. That comes right from Penn State’s Irrigation water quality guidelines for turfgrass sites. Were you surprised by the previous post that worked out daily Ca use by the grass, and Ca added in irrigation water, to find that irrigation water was supplying 26 times more Ca than the grass was using?

Calcium leaches?

Did you see where soil potassium (K) only went down by 1 ppm after 374 mm (14.7 inches) of rain? In that same comparison of pre- and post-rain samples, the soil calcium (Ca) went down by 26 ppm.

Airplane fuel requirements, soil test calcium, and MLSN

Grant Saunders asked a series of questions about the quantity of nutrients required in the soil, using calcium as an example. One can see that full discussion here. When he asked this question, I thought the clearest way to answer it would be with a blog post.

No matter how much sodium one puts into a sand rootzone, the soil structure cannot be affected, so gypsum won’t be required

I received this question about leaching salts from the rootzone: “I remember talking to you once before regarding flushing excess salts from the root zone and the application of gypsum or other calcium products before the flush and you telling me it was not necessary.

3 decades to use all calcium in the soil?

Frank Schäfer wrote with this question about calcium: For the Calcium Post, you wrote that it would take three decades to use all Calcium in soil on an average bulk content.

“Available” calcium, soil pH, and fearmongering

I did an experiment in a greenhouse in which I grew creeping bentgrass in four different sands. I collected all the clippings and measured what was in them. And I tested the pH of the sands, and I did soil tests to measure the soil nutrient content.

"The salesmen all suggest Calcium"

Jason Chennault and I had a conversation about interpreting soil tests. I had seen test results for a site and didn’t think there were any problems with the soil. Jason wrote back with more information.

Waterfall chart of putting green calcium levels

A waterfall chart can be used to represent nutrient availability and use in turfgrass. This waterfall chart for calcium (Ca) takes a look at the Ca in the soil and shows the various additions and subtractions of calcium over the course of a year.