growth potential

I showed in part 1 how one can go from temperature to a temperature-based growth potential to a standard N amount. By looking at the actual N applied, and comparing that amount to the standard N for any location, one gets what I call the genki level.

This is one I’ve been thinking about for a long time, and have discussed with many turf managers, but I don’t think I’ve explained it on the blog yet. So here goes.

Some years ago I shared some articles that I often referred to or recommended, and I called that Five articles every greenkeeper should read. As I look at this list of articles now, I’m reminded of the familiar maxim about understanding the rules before breaking them.

Those are the results Jason Haines described in his post about the evolution of precision fertilizer application. He explains how he makes use of observations, measurements, and predictions to find site specific nutrient requirements.

Last week I wrote about some calculations to find the inflection point when the temperatures change from being better for warm-season grass (like bermudagrass, seashore paspalum, or zoysia) to being better for cool-season grasses (like perennial ryegrass, creeping bentgrass, or kentucky bluegrass).

The turfgrass growth potential (GP) is a number that represents the proximity of the actual temperature to the optimum temperatures for growth. GP is used for a lot of things. One can use it to make estimates of nutrient use, estimates of topdressing amounts, and to find the time in autumn when the cool-season growth potential starts to exceed the warm-season growth potential.

PACE Turf have prepared this spreadsheet that takes inputs of average temperatures and a maximum monthly topdressing rate, and gives outputs of estimated monthly and annual topdressing sand amounts. It is a metric version of this:

Every now and then I get some questions about the temperature-based growth potential (GP). The most recent question was about relative humidity: “I am curious about the effect relative humidity has on growth potential?

There’s a new spreadsheet available from PACE Turf that uses the temperature-based growth potential to estimate the quantity of sand required as topdressing. They wrote: “To get a rough idea of how much sand to apply over the course of the year, we have developed a simple spreadsheet that uses growth potential (GP) as a guide, and a maximum sand application of 150 lbs dry sand/1000 ft2 per month at maximum turf growth.

Do you remember the amazing story from Thomas Sedlmeier who wrote to me last November? He introduced himself, explained how he had started using MLSN and GP, informed me that the grass conditions were beautiful, and also shared some information about maintenance expenses.