The ATC blog has moved

After eight and a half years, and 841 posts, I've moved the blog to More details about that at the end.

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That first post about Banyan GC in Hua Hin sure seems like a long time ago!


What's going to happen with the 841 posts that are here now? I'm going to leave them just as they are, for now. I may migrate them to another address sometime, but I'd like to do that while still having pointers to the new location from the existing addresses, so I don't break too many links. Since I don't know how to do that right now, I'm not going to rush to change anything. For now, just expect this to be as it is, and all new content is going to be at

Why make the change? I have a few reasons.

  • It will be easier for me to write and make use of what I've written using the new setup
  • I think the new site looks better and I hope you do too
  • The new site should load faster

I've used the Beautiful Jekyll template to generate the new site. I write posts in Markdown, Jekyll generates a static site, and there you have it. And I get to have my blog in plain text and under version control, which is useful for me in a lot of ways. For example, A Short Grammar of Greenkeeping is written in Markdown too. If I want to make books or booklets with some of the content from the blog, it is going to be a lot easier if I have it all in folders on my computer in plain text files, rather than in messy HTML in databases on some server I don't own.

Plus, it's faster and looks better.

Turfgrass roundup: June 2017

Three points about turfgrass roots and fertilizer.

Frank Rossi, Dan Dinelli, and Roch Gaussoin on TurfNet Radio talking organic matter.

Zoysia growing into bermuda at 6.8 cm per month.

Matee Suntisawasdi with photos of zoysia greens in Thailand:

Predictions about turfgrass and climate change in a new paper by Jerry Hatfield.

How much nitrogen is in rain and snow?

The Asian Tour was in Samui for the Queen's Cup:

A correspondent asked, about fertilizing based on soil salinity, "is there a particular reason you think it's a poor way to fertilize?"

About soil salinity, fertilizer, and not jumping on bandwagons.

Fertility might not mean what you think it does.

Reinders with a summary and lots of photos in a U.S. Open volunteer recap:

Jason Haines says measurement of clipping volume is "already proving to be more valuable that I originally expected".

And with all the measuring, he hasn't found any "increase in time that it takes to cut the greens in the morning."

He also wrote about growth rate and disease.

And extreme growth rate turfnerdery.

Do the MLSN guidelines include all 17 essential elements?

Gypsum isn't required prior to leaching salt from sand rootzones.

I'm confident that when grass grows less, the green speed will be faster.

Paul Robertson started an extraordinarily long and wide-ranging conversation with a simple question: anyone using a Pelzmeter?

"Sorry if this is a rubbish question," a correspondent wrote, about different MLSN guidelines for different grass species.

Are you subscribed to the ATC updates mailing list? Or the MLSN newsletter list?

For more about turfgrass management, browse articles available for download on the ATC Turfgrass Information page, subscribe to this blog by e-mail or with an RSS reader - I use Feedly, or follow asianturfgrass on Twitter. Link and article roundups from previous months are here.

"Sorry if this is a rubbish question"

This question came some months ago:

"I'm just pondering something about MLSN levels for Bent vs Poa and so hopefully you can clear it up.

Having seen a bit of research coming out about k levels affecting disease pressure differently for poa and Bent does that not mean there should be two different MLSN's for the two species?

Sorry if this is a rubbish question, I might have missed something somewhere."

That is not a rubbish question. There are three general points I'd like to make about this.

  1. MLSN is a method for interpreting soil tests to prevent deficiency. That is, MLSN is designed to be conservative. The MLSN guideline serves as a quantity of K in the soil that the grass will never touch. The amount of K recommended as fertilizer using the MLSN approach differs based on three things: grass type, growth of the grass, and the quantity of K in the soil. The fertilizer recommendation for K changes for every situation, but the MLSN guideline remains the same.

  2. This article by Doug Soldat has more about varying K fertilizer amounts and bentgrass and Poa annua diseases. If one wants to adjust the K fertilizer in an attempt to incite or suppress anthracnose or snow mold, or winter kill, then one might err on the side of a little bit more K for Poa in summer, and a bit less K for bentgrass, especially in autumn.

  3. MLSN is meant to be simple, and is meant to answer two questions. Is this element required as fertilizer? If the answer to the first question is yes, then the second question it answers is "how much of the element is required?" It is meant to err on the side of recommending too much, rather than too little. One can use those recommendations as a reference, and then if one wants to try to reduce the intensity of snow mold, then cut the K.

"I don't really need to show any data for this to be certain"

After Paul Robertson asked if anyone is using a Pelzmeter, a long discussion followed, and the notifications on my Twitter account blew up. I think the conversation is still happening.

My only contribution to that conversation was to share a link to an article by Richards et al. that shows the Pelzmeter and the Stimpmeter give the same results with "no differences in measurement repeatability."

The conversation kept going, eventually touching on the quantity of clippings mown from the turf, which is some indication of how much the grass is growing, and the green speed. I was reminded of a question from a correspondent a few months ago. He wrote with this question:

"Have you correlated yield to speed? I have to assume that as yield changes speed changes also."

I replied:

"In the big picture view, yes the clipping volume will be negatively correlated with speed. When clipping volume goes up, the speed has to go down.

I don't really need to show any data for this to be certain. Take, for example, warm-season greens. Are they faster when growing in August (clipping volume is a positive number), or when dormant in February (clipping volume is 0)? They are lightning in February and of whatever speed they are in August.

I attach a chart with clipping volume in L/100 m2 (same as quarts per 1000 ft2) on the x axis and green speed on the y axis. That's from a couple years of tournament week measurements in Japan. Speed is affected by other things but the clipping volume is sure to have some effect and I don't think it will ever be in the direction of more growth = faster speeds.

This is the chart I attached.


Today I looked up the data from 2016 and added it to the chart, and this includes a couple measurements from July 2016 a month before the tournament week.

Here it is without the July measurements.


And here are the data broken down by year.


Bill Kreuser showed data on bentgrass where the quantity of clippings was not related to the previous day's stimpmeter measurement. Those data are surely correct. But if one thinks about the big picture view, of the range of growth rates one can have over the course of the year, and the range of green speeds, I think it makes sense to think of green speed as being affected by how much the grass is growing.

And this leads me to something else that I can't help but mention. Bill can show data that demonstrate an interesting point; clipping yield was unrelated to green speed under the conditions of his experiment. I can show data that demonstrate an interesting point; clipping volume in the situation I describe is obviously associated with green speed. These experiments are not that hard to do; one could generate some kind of data about green speed and could make it show whatever one wanted to, if one planned it right, because there are a lot of factors that influence green speed! So why is it so difficult to find data about Si and green speed? I still think it is ridiculous that a stiffer leaf would make for a faster green speed.

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. I have since discovered that same conclusion for myself. I remember you sent me an article or a link to one of your blogs but I can't seem to find the email or article. Could you please send it to me again?"

I wrote back:

I don't recall that I've written anything specifically about that. I have written about Ca not being required in sand rootzones for the purposes of dealing with sodicity issues, because no matter how much sodium one puts into a sand rootzone, the soil structure cannot be affected, so gypsum won't be required. Relevant blog post:

Is sodium an imaginary problem?

Also, this: water and soil handout.

I have made a note to write a blog post [and here it is] about leaching salt from sand rootzones and Ca not being required. I'll do that sometime.

Real quick, water problems are divided into 3 main categories, and each has a different solution.

Salinity -- this is the total salt. The solution to salinity problems is to add extra water to leach the salts below the rootzone. No Ca is required for this. The water does the leaching.

Sodicity -- this is a soil structural problem that occurs in soils when the sodium gets too high. It is defined as exchangeable sodium percentage > 15%. This is irrelevant in sand rootzones because the sodium does not cause any structural problems in sand. This is a problem in clay soils. The solution to this problem is to add gypsum. The Ca in the gypsum then replaces some of the sodium and restores the soil structure.

Saline-Sodic -- in this case, the sodicity occurs and is combined with high total salts. Also irrelevant in sand rootzones because of reason mentioned above. The solution to this problem is to add gypsum, to restore soil structure, and then to add extra water to leach the salts.

17 essential nutrients?

"Do the MLSN guidelines use 17 essential nutrients?" a friend asked me last month. "I've found a couple good articles but couldn't really find a number on the MLSN website."

"That's an interesting question," I replied, "and I may answer it on my blog. I can explain the 17 and you'll be an expert."

Here's how it works, and how soil testing and the MLSN guidelines fit in. I'll describe this in four sections.


First, what is an essential element?

To be classified as essential, the element must meet three criteria, as described in a classic 1939 article by Arnon and Stout. An element is essential if:

  1. a deficiency of that element makes it impossible for the plant to complete its life cycle.
  2. the deficiency can only be corrected by supplying that element; the function of that element cannot be substituted by another.
  3. it is directly involved in plant nutrition (plant metabolism), and is not merely correcting a soil chemical or microbiological condition.

Second, what are the essential elements?

Or more specifically, where does the 17 (or sometimes 14) number come from?

Well, we can start with carbon, hydrogen, and oxygen. These elements are what Carrow et al. call the basic nutrients. These elements are never required as fertilizer, because they are never deficient. The grass gets them from CO2 and H2O.

Then there are what are usually called the macronutrients. These are nitrogen, potassium, and phosphorus. These elements are often required as fertilizer.

Next come the secondary nutrients. These are still in the macronutrient range (more than 0.1% [1000 ppm] by dry weight), but are rarely required as fertilizer. The secondary nutrients are calcium, magnesium, and sulfur.

And then there are the micronutrients. These are used in small amounts by the grass, from less than 1 to 500 ppm in the leaves. The micronutrients are iron, manganese, copper, zinc, boron, molybdenum, chlorine, and nickel.

If you add all those up, the basic, macro, secondary, and micronutrients, you get 17 in total. That's where the 17 number comes from. Because the basic elements carbon, hydrogen, and oxygen are ubiquitous and are not applied as fertilizer, those three are often omitted from discussion and the list of essential elements is given as 14 in total. And occasionally there will be one of the micronutrients omitted; for example, the excellent Turfgrass Fertilization: a basic guide for professional turfgrass managers from Penn State omits nickel and gives the total as 16 elements. Which is fine, as I'll explain in the fourth section, below.

Third, do the MLSN guidelines use all 17?

Yes. And no. The MLSN guidelines provide a framework for ensuring that any grass, at any location, will be supplied with all the nutrients required by the grass. And yet the MLSN guidelines only list a minimum value for five elements: potassium, phosphorus, calcium, magnesium, and sulfur.

The MLSN guidelines are used to interpret soil test results. We don't soil test for the basic elements. Those are never deficient. And one doesn't make fertilizer decisions about nitrogen for turfgrass based on soil tests either, so we don't include nitrogen in MLSN (see N & MLSN, what's the connection). All the other macronutrients and secondary nutrients have a minimum guideline using MLSN. And we deliberately don't worry about micronutrients too.

Fourth, what about micronutrients?

I don't worry about them very much. I've explained this in detail in these two posts:

Quoting from my comment in one of those posts:

the quantity of micronutrients the grass uses is so tiny as to be almost negligible. And we constantly keep the growth of the turf -- and consequently its demand for nutrients -- restricted by applying less nitrogen than the grass can use. Thus the probability of a micronutrient being deficient is very low ... Let's say grass uses 10 g N/m2 per year. It uses progressively less K, then P, then Ca, Mg, & S. By the time we get to the most used micronutrient (Fe), we are looking at only 0.025 g/m2 per year. 25 mg! And the other micronutrients are a fraction of that. In practical terms, there is almost no way a micronutrient can be deficient in turfgrass, and it is so easy and cheap to just spray out a complete micronutrient package at a tiny dose. There is really no need for soil testing for micronutrients in turf.

Which is why I think it is fine that the guide from Penn State omits nickel. When it comes to the micronutrients, the grass uses such a tiny amount that one doesn't have to worry much about them. And if you are worried about a micronutrient deficiency, or want to be especially sure that the grass has enough micronutrients, then it is easy and inexpensive to apply all the micronutrients that the grass can use. There is no excuse for a micronutrient deficiency.

"Already proving to be more valuable than I originally expected"

2017-05-23 13.23.54

When I read Jason Haines' interesting post about clipping yield, soil mineralization, and disease rates and came to the part where he said measuring all the greens was more valuable than he expected, I was glad to read that. I wanted to say "I told you so," because this is a number that I think is really useful. And I hadn't thought of the disease connection and being able to notice that, but I do know that golf course superintendents will find ways that I haven't thought of to make use of growth data. Because managing the growth rate of the grass is what it all boils down to. I've written about this in the Short Grammar of Greenkeeping. And it makes sense to me, when the clippings are collected anyway, why not take note of how many there are?

Chris Tritabaugh has a thread about this, asking what about the fertilizer that wasn't applied? And he finds, if I understand correctly, that monitoring the clippings gives some confidence that more N is or is not required at a given time.

Which is where I decide to jump in here with two quick comments. First, yesterday I had the great pleasure of writing about fertility. Now I want to mention programs. Specifically, fertility programs. I don't think program is the right word to use when considering the nutrient supply to turf.

Program means a plan of activities, or a sequence of operations that can be set to happen automatically. But with turfgrass, one can assess, as Chris wrote, "the nutrients we haven't applied" by measuring how much the grass is growing. That is, the grass is likely producing some growth in response to fertilizer applied in the past (see this for more) and one expects there is some growth related to mineralized N too.

Let's say one wants to have a flexible fertilizer system. FFS. Has a nice ring to it. Measuring the growth allows one to adjust the nutrient supply based on the grass response. Whatever one wants to call it, I think turf response will almost certainly be better, and fewer inputs will be required, if the N rate changes at almost every nutrient application. This is what the temperature-based growth potential method is based on, to set an upper limit of N supply at any time, given the weather, and then that predicted amount to supply is adjusted based on the actual grass response.

Now my second point, which is more about the utility of clipping volume. Or about mineralized N. One can expect a soil with a 10 cm rootzone depth and 1% organic matter to release about 2 g N/m2 in a year. And a soil with 2% OM may release about 4 g N/m2. For creeping bentgrass maintained at relatively low N, I expect that will produce from 50 to 100 g dried clippings per m2. And based on the relationship between clipping volume and dry weight for bentgrass, I expect that will work out to a fresh clipping harvest of 80 to 160 L/100 m2.

That is, one can predict how much extra the grass may grow after one knows the organic matter in the soil. I expect this makes sense to anyone who has put a number to the clippings mown off the putting greens, and is gibberish to everyone else. But the approach of working with quantities of nutrients in the soil, quantities of nutrients harvested, and quantities of nutrients supplied as fertilizer, allows one to get really precise, and really efficient, and supplying just what the grass requires.

And the implications are that one gets better grass conditions, one does so with less work, one has more control of the grass conditions, and there is potentially less coring, less topdressing, less disruption of surfaces, less Poa annua invasion, etc.

Tonight's reading


I saw a video today with the question "what is your favorite fertility practice?" That segment starts at the 2:00 mark.

Then on Twitter I saw some comments about how funny the answers to that question were. I had a laugh because the answers are correct, but it is the question that misuses the word.


I don't expect the turf industry will change its jargon on this. But if one misuses the word fertility in conversations with the general public, it should not be a surprise if the responses are about fertility.

"Don't try to jump on his bandwagon"

Jon Scott wrote to me about my recent post on a poor way to fertilise.

"While this superintendent has solved his problem of nitrogen input by monitoring salinity level that has worked for him, this is probably a very unique situation. It may be relevant to other golf courses where similar salt levels exist, but there are too many variables to draw general conclusions. Thus, I would focus on salt levels as related to this situation and not extrapolate. What he has said may be relevant to similar situations, but it all depends on the salt levels."

I agree, and I meant to make that clear in the original post. Let me try now to explain in clear terms.


If there is a salinity problem at a site, then one will always want to minimize the salinity in the soil. If one is always trying to minimize salinity in the soil, then it is impossible to use any measure of salinity as a criterion for fertilizer application.

In a case where there is not a salinity problem at a site, it might sound reasonable to try to use salinity as an index of nutrient content in the soil. However, there are three big problems with this, and these I did describe in the original post. First, most turf managers don't want fluctuating nutrient supply; second, salinity says nothing about which nutrients are there; and third, the salinity measurements from soil moisture meters, whether EC or a salinity index, are so affected by the water content of the soil that using the salinity of non-saline soils to make decisions about fertilizer is like chasing a target that moves randomly.

I like using soil moisture meters to measure the water content in the soil. I think it is useful to assess the salinity of the soil with the meter too, if that function is available. But I don't think it is a good idea to make fertilizer decisions based on soil salinity.

I replied to Jon that "I think it is ridiculous but tried to be as polite as possible."

He wrote back:

"You, trying to be polite? Don’t lose your edge ... I think you need to clarify how unique this situation is so that others don’t try to jump on his bandwagon. His premise is flawed when applied outside of his operation."

6.8 cm per month

A few years ago I wrote about how everyone knows zoysia grows slower than bermuda, except when it doesn't. In particular, I was discussing the growth of the nuwan noi variety of manilagrass (Zoysia matrella) in tropical Southeast Asia.

One of the examples I used in that post was the expansion rate for patches of nuwan noi in the bermudagrass fairways at the Santiburi Samui Country Club. I was back at Samui this week, and I went to the 18th hole to check the nuwan noi.


Just around the dogleg, and down the hill near the landing area, there is a large patch of nuwan noi that has overgrown the bermuda.


I paced it off, and the diameter of that particular patch is now 17 meters. If that started as a single plant in January 2007, and has now grown 8.5 meters in every direction, then the expansion is 850 cm in 125 months, or 6.8 cm per month.

This approximate rate keeps coming up in a number of measurements I've made. I have estimated the expansion at 7 to 8 cm per month. And in pot experiments, I get a similar rate too. For example, planting nuwan noi stolons at a rate of 1,500 nodes per square meter gives 1,500 nodes in 10,000 cm2. If each node occupies 1 cm2 at the start of the month, and then the coverage goes from 1,500 to 10,000 cm2 by the end of the month, that's an expansion rate of 6.7 cm2 for each plant in a month.

Why does this matter? Because I've hypothesized that the most sustainable grass for a given location is the one that has the most growth per unit of N and per unit of H2O applied.