## The eloquent Edwin Roald on Bogey Nights

##### 07 October 2015

This is a conversation I really enjoyed, and I think you will too. Edwin has some great ideas about matching the time window of a round of golf to the way we live today. And the implications of this are many -- time, cost, resources, quality, and land use are all naturally influenced by what he has to say.

This fascinating conversation is less than 15 minutes. Have a listen here: Edwin Roald on Bogey Nights, or visit why18holes.com for more information.

Another note of interest is this. Jason McKenzie, one of the hosts of the Bogey Nights show, worked in golf course maintenance during high school before going on to play golf at Mississippi State University. There is a lot of talent and knowledge on this radio show, and I'm glad I had a chance to listen.

## The data prove me wrong

##### 06 October 2015

I was listening to Frank Rossi talking with Bert McCarty on the TurfNet Radio Network. It was an interesting conversation, about lots of things including ultradwarf bermuda, pigments, and heat stress on bentgrass.

One thing struck me when they were talking about ultradwarf bermudagrass, and Rossi mentioned that "light levels change, maybe temperatures change, but certainly light levels is a driving force" in the slowdown in growth at the end of summer. McCarty confirmed that "light starts it off" as the "grass starts to slow up" even though it is still hot.

I wondered if that was right. It seemed to me that temperatures would go down to slow growth before light would. Well, I looked up some data, and they were absolutely right.

Here's the average monthly temperature for the last 10 years at McClellanville, South Carolina. Temperatures for 2015 are included to October 4. Looks like July and August are the hottest months, no surprise, and I see a drop going to September.

Then I looked up the global solar radiation, converted to photosynthetically active radiation expressed as a daily light integral, and calculated the monthly averages. Again, 2015 data are just up to October 4. The DLI peaks in June and then looks like a steady decrease to December.

Ok, I had the temperature and the light, but how to see which one is dropping off at a different time? To do that, I looked at the change from month to month. I calculated something called the log percent (L%), which is $100(log_{e}(y/x))$. In this case I let $y$ be the value for the month, and $x$ be the value for the previous month. This calculation gives a symmetric, additive, and normed measure of the relative change in light, and of the relative change in temperature.

I didn't compare December to January, so there is no L% for January. That's alright, because I was most interested in what happened at the end of summer, specifically in August and September. The values on this chart for February represent the L% change from January, March shows the change from February, and so on.

It is really clear. Dr. McCarty was exactly right.

In July the temperature is still increasing from the previous month, and light is decreasing from its peak in June.

Then in August there is a big drop in light, and on average no change in temperature. And even in September, the relative drop in light is higher than is the relative drop in temperature. It is not until October and November that the temperature decrease is more than the light decrease.

It's good to know this!

## "As clear as mud"

##### 04 October 2015

This was the most disappointing thing I've read all year. Why it was disappointing, and avoidable, I explain below. But first, here it is, from Mark Hunt's Weatherblog, reporting on his seminar experience at the Golf Industry Show earlier this year:

"The U.S appears to have come full circle with respect to soil analysis with their lecturers now referring to Base Saturation as a discredited system for calculated nutrient input from soil analysis.

Slightly hypocritical when you consider it was the U.S that led the foisting of this approach on our industry over here and I can clearly remember attending classes 15 years ago when they advocated this system.

Now they are relying on SLAN (Sufficiency Level of Available Nutrients) for their soil analysis but they have no guidelines and little new credible research to back up recommendations. I came away from the classes in this area with a book full of conflicting notes and a comment “As clear as mud” written by me in bold."

Three things are terribly wrong and disappointing here.

First, no one should have that kind of experience at a seminar or educational conference about turfgrass nutrition. To be reporting that things are "clear as mud" after taking the class is really an indictment on what is being taught. And that is unfortunate, because this subject is not a complicated one. It should be clear as crystal, or whatever the expression is, rather than clear as mud.

Second, Hunt's memory of BCSR being advocated 15 years ago -- I expect that was being advocated either by those selling fertilizer or selling soil testing services. I'm not aware that BCSR has ever been advocated by turfgrass scientists. But that confusion still exists over BCSR in the turf industry is also unfortunate. It's really simple. Don't worry about cation ratios in the soil. They are irrelevant. And anyone teaching on this topic should make this clear.

Third, to convey that there are "no guidelines and little new credible research" -- who ever is teaching that should be more clear. On the contrary, there is tons of credible research, and it all points to the same thing. And that is, one just needs to make sure the grass is supplied with as much of each element as it will use. If there is already enough of that element in the soil, then no more needs to be supplied as fertilizer.

That approach, supported by extensive research, is the basis of the MLSN guidelines.

Bill Kreuser gave an excellent seminar on this for TurfNet: Making Soil Tests Work for You. In the seminar, he mentioned that "you can grow really great turfgrass without dealing with this kind of craziness."

Also from Kreuser, this guide: Simplifying soil test interpretations for turfgrass professionals.

There is lots more about guidelines and credible research. See, for example:

The point is, this is a simple topic and for someone attending an educational event, trying to learn the latest about turf nutrition, to be left with the impression that things are unclear -- well, it shouldn't be that way, and that's why Mark Hunt's review of the Golf Industry Show was the most disappointing thing I read this year.

To close on a related, and more positive note, I've read lots of great things this year and can't pick a favorite at the moment, but this from Jason Haines' Turfhacker blog is very much on this topic, and is one of the better reads:

"the greens are better than ever and I no longer worry about locked up nutrients in the soil. It's not that difficult and I highly recommend you stop worrying about it and adopt these fertilizer guidelines now."

## Monthly Turfgrass Roundup: September 2015

##### 02 October 2015

Here's a roundup of turfgrass articles and links from the past month:

This, by Hellacam, is the best course video by drone I've seen -- of Clearwater Bay Golf and CC in Hong Kong.

Clint Mattox's thesis has some great new information about managing microdochium patch using non-traditional fungicides on annual bluegrass.

Govindan Sivakumar shared this photo of repairing from the real elephant's footprint:

Jim McLoughlin on Turfnet about superintendents and consultants.

A year of weather in Georgia, Japan, and Mississippi.

Dave Wilber had some great conversations on his new Turfgrass Zealot Project.

Clipping volume from putting greens with data over multiple years.

Temperature and light and their relative effect on turf.

Allen Dewald with this photo of turf at the end of the season:

Easy explanation of PAR, PPFD, and DLI.

If turfgrass growth were a recipe, these are the ingredients.

Are weed problems related to energy for growth?

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.

## Energy for growth, and weeds

##### 29 September 2015

Two things today are kind of related to this topic. One is this -- Jim Brosnan mentioned, and showed photographic evidence, that "weed pressure on Oahu never ceases to amaze."

And I had a conversation with a golf course designer about fine fescue as an infrequently mown rough, in what climates that species can work, and what happens when it is too hot for fine fescue. And I mentioned that one can plant a number of species other than fine fescue in a warmer climate, but the problem becomes one of "how can we find a ball" because there is a lot of energy for growth. Of course there are various techniques turf managers can use to solve that problem, but then the turf will be alive, but thin. It must be if one is going to find a ball in it.

Once there are voids, weeds have an opportunity to grow. Turf managers can solve this problem too, with herbicides, or with manual removal of weeds. But now comes another problem. That is erosion, in locations with substantial rainfall.

Anyway, it must be that the growth of plants (desired species, and weeds) is related to the energy available for the plants to grow. In general the hotter it is, the more energy there will be for weeds, so when one thins a low maintenance rough, the energy for weed growth or invasion is going to be more in a hotter climate than in a cool one. I looked up some data from Japan -- hour by hour data of temperature and global irradiance for 2014 at Sapporo, Tokyo, and Naha. Then I converted the irradiance to photosynthetically active radiation (PAR) using a factor of 2.04.

I looked only at day time, when the sun was above the horizon. And I arbitrarily cut the data to look only at those hours when the temperature was greater than or equal to 20°C. Then I added up all the light, and all the hours. This is a very rough index of how much energy there is for growth, especially for the weeds that will grow when it is hot. And it is a conservative estimate, because the night temperatures influence growth too, and so does the actual temperature. This is just a quick way to note the differences between locations.

At Sapporo in 2014, the cumulative sum of PAR for hours when the temperature was greater than or equal to 20°C was 3,781 mol m-2. Tokyo has 5,844, and Naha was 9,124. Oahu is considerably warmer than Naha, so it almost certainly would have more PAR than Naha at this cutoff value.

Just looking at the time, how many hours were there for weeds to grow well in these different locations, by looking at how many hours there were with a temperature at or above 20°C? At Sapporo, there were 1,365 of these hours; at Tokyo there were 2,503; and at Naha it was 3,805. Again, locations in Oahu would almost certainly be more than Naha.

That is a real quick estimate of how much energy there is for weeds to grow, or more specifically how the energy is likely to differ in magnitude from location to location.

And one more thing -- in Scotland where a fine fescue rough actually works well, how much energy would there be for weeds? I don't have the exact irradiance data for Scotland, so I won't try to compare it to exact measurements. But I can give some idea of just how much lower the energy is, or how much lower the duration of time would be for weeds to grow rapidly. Huge disclaimer is necessary here, because the species are different, so a C3 weed like Poa annua might grow relatively rapidly in Dornoch but I am considering more the C4 weeds like Paspalum dilatatum or Cyperus rotundus.

It still makes an interesting comparison. Of Naha, Tokyo, and Sapporo, Sapporo is by far the coldest. And in the hottest month of the year in Sapporo, the average low temperature is 19.1°C, and the average high temperature is 26.4°C. How about somewhere in Scotland where fine fescue grows well? I picked Leuchars, just north of St. Andrews. In the hottest month of the year in Leuchars, the average low is 10.8°C, and the average high is 19.2°C.

## A turfgrass recipe, with ingredients

##### 28 September 2015

Today I have two seminars at the 北海道グリーン研究会 autumn meeting. That's the Hokkaidō gurīn kenkyūkai -- the Hokkaido green research association. You can view or download the presentations and handouts at the links below.

The first presentation is called If turfgrass growth were a recipe, these are the ingredients.

There are four main factors (ingredients) that influence growth. These are temperature, water, light, and nitrogen. And one can either measure or control each of them.

Adjusting the growth rate of the grass is what greenkeeping is all about. And being able to measure and control the "ingredients" allows one to compare maintenance at one site to another, compare differences from year to year at the same site, and adjust inputs for different species. This provides a template for improvement of the turf through adjustments to the growth rate.

The second presentation is called How I would manage bentgrass greens today.

I explain how I would measure and control the ingredients of growth, and explain how I would do it differently today than I did 15 years ago when I was a greenkeeper managing bentgrass greens in Japan.

## An easy PAR

##### 24 September 2015

That's the title of my column in the September/October issue of GCM China. I wrote about light:

"It isn’t that difficult once one understands the terminology and the units of measurement. There are just three technical terms to learn, and after that, it is all quite clear."

Those terms are:

• the light grass can use is photosynthetically active radiation (PAR)
• to find out what PAR is at any moment, one measures the photosynethetic photon flux density (PPFD)
• to measure PAR for a day, add up all the PPFD from sunrise to sunset to get the daily light integral (DLI)

## Multifunctional golf facilities: a handbook and an article

##### 22 September 2015

"During the spring of 2015, the multifunctionality of two golf courses in the Stockholm region were studied. 30 different activities were identified on and around the two golf courses!"

If that sounds interesting, check out these two new documents from STERF explaining more about their multifunctional facilities project:

## 'Tis the season

##### 19 September 2015

Autumn is when one can find one of my favorite turf diseases -- elephant's footprint. Or at least this is my favorite name for a turf disease. It is found most often on unmown Zoysia japonica.

Al Bancroft shared a photo last week of what looks like early development of elephant's footprint.

This is what the classic symptoms look like, further into autumn:

I was also reminded this week that real elephant footprints can be a turf problem too:

That's in Tamil Nadu, where one must beware of elephants.

For more about real elephant footprints on turf, see this turfgrass mystery.

## Indices of temperature and light and their relative effect on turfgrass

##### 18 September 2015

These values are calculated from the daily weather data in 2014 at Holly Springs, Mississippi:

• the temperature-based growth potential for cool-season (C3) grass, labeled here as gpC3
• the temperature-based growth potential for warm-season (C4) grass, labeled here as gpC4
• the daily light integral (DLI) divided by the maximum possible DLI on that day, labeled here as dli_index

Each of the three values have been calculated for each day of 2014. That gives 365 values for gpC3, 365 for gpC4, and 365 for the dli_index.

These histograms, with the breakdown of what values were for these three calculations,  show why I say that variations in temperature affect growth more than variations in light.

For the DLI index, there are few values around 0, and many above 0.75. There are about 90 days for C3, and more than 150 for C4, with a growth potential of about 0.