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November 2015
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December 2015

A wide-ranging conversation with Dave Wilber

Dave Wilber's Turfgrass Zealot podcast on TurfNet is reliably interesting. It is interesting for turfheads, at least, in Wilber parlance.

I was thrilled to join the project and to talk with him last week for episode 14. We had a wide-ranging conversation about a lot of things -- carbon, soil testing, islands, tourism in Thailand, nonsense, what time of day stomata are open, vending machines, how much potassium one can expect in the soil of a putting green, and so on. You can listen to our discussion here:

And for a bit more about Dave Wilber, this Golf Club Atlas interview from 2006 is full of interesting information and stories.

Top 10 posts on the blog in 2015

These are the 10 blog posts in 2015 with the most pageviews.

  1. 2 similar approaches to fertilization, with 1 notable difference
  2. "As clear as mud"
  3. Silica and green speed
  4. "Beware! These topics are misleading and irrelevant"
  5. Two short articles on simplifying fertilization and soil test interpretation
  6. How windy was it in St. Andrews yesterday?
  7. "No more than one third of the total leaf surface ...
  8. Course maintenance photos from the U.S. Open at Chambers Bay
  9. Concerning the availability of nutrients in soil
  10. Seminar questions: availability (again) and foliar applications in the context of soil guidelines

A look at pageviews in 2015, and my 10 favorite posts that didn't make the top 10

Tomorrow I'll list the 10 posts with the highest pageviews this year. Today, a quick summary of all 139 posts so far in 2015, and my pick of 10 posts that I really liked but that did not make the top 10 in pageviews. Here's a histogram of pageviews for all posts in 2015.

2015_histogramThe most viewed post had 868 pageviews; the least viewed had 14. The median views for all the posts was 98; 25% of the posts had less than 67 views; 25% of the posts had more than 190 views.

This violin plot shows all the posts.

Violin2015And here's my selection of the 10 posts that didn't make the top 10 in views, but that I really liked.

  1. Maximum wind speed for each of the past 609 July days at RAF Leuchars, which shows just how extraordinary the wind speed was when play was suspended at the Open Championship.
  2. Morning and afternoon shade with PPFD capped at 1000, exploring the question of whether morning shade or afternoon shade is more detrimental to cool-season grasses.
  3. What happened on January 16, or how to increase interest on what you tweet by more than 75%: everyone is busy, no need to clutter their feeds with junk. Getting rid of automated tweets can increase interaction too!
  4. This is what PAR looks like, showing photosynthetically active radiation (PAR) every 5 minutes on a cloudy day, sunny day, a week, a month, and a year.
  5. Tournament week clipping volume, in which I make a case for routine measurement of clipping volume as being a useful piece of information.
  6. A chart of PPFD at two locations this year from January 1 through last Friday, the most intricate chart I made this year.
  7. Estimating turfgrass nutrient use, which is pretty much the key thing to estimate when determining how much fertilizer to apply.
  8. Surprises, conservatism, and what one can learn from soil testing, part 1: describes an experiment in Thailand, and some extended thoughts on these topics.
  9. Nonsense, facts that aren't facts, and turf in 3 dimensions: I even got blocked by Steve Keating's account after this post!
  10. Botanizing in Bangkok, about tropical grasses and the largest grass collection I've seen in Southeast Asia.

A similar report on the pageviews from 2014 is available here.

Map of all the flights I took this year

I made a map of all the flights I took this year. The code I used to make the map is based on this.

Flights2015After seeing the map, I scrolled through my photos from these places. It's been an extraordinary year for studying grass around the world.

Korai lawns in central Tokyo.



Bermudagrass in India.


  Golf turf in early summer.Ice

Bermudagrass at the Girona Temps de Flors.


  Bermudagrass and Hordeum.Hordeum

At Harpenden, different species grow where different fertilizers have been applied.


At the Cascade Head Prairie, some of the same species as found at Harpenden.


Amazing color of fine fescue at Chambers Bay.


Manilagrass lawn beside the beach in Bali.


Seashore paspalum at SCG Stadium in Bangkok.


Read these articles, but disregard the subtitles

When I saw there was a new article at Golfdom about sodium causing agronomic challenges on sand putting greens, I clicked the link to see what this was about.

That link took me to the article by Obear and Soldat in which they explain that sodium does not cause agronomic challenges in sand putting green soils:

"Sand putting green soils have low clay contents and are therefore unaffected by sodium ... The findings from this study suggest that sodium will not negatively affect putting green soils with low clay content, including those constructed to USGA recommendations ... In the case of sand-based putting green root zones, which often have very low clay content, increasing exchangeable sodium percentage well above the standard sodicity threshold of 15 percent had no effect on hydraulic conductivity."

But the link is, which seems the opposite of what the article is about. Sodium causes agronomic challenges for sand putting greens? Maybe if the sand putting green is made of clay.

That reminds me of the subtitle for the article Frank Rossi and I wrote about the Park Grass experiment for the Green Section Record. One of the things I thought was amazing was how soon the botanical composition on the Park Grass field changed in response to fertilizer treatments. We wrote about that in the article, quoting Lawes and Gilbert from their first paper on the botanical composition of the experiment, published just a few years after the first treatments were applied:

"the plots had each so distinctive a character in regard to the prevalence of different plants that the experimental ground looked almost as much as if it were devoted to trials with different seeds as with different manures [fertilizers]."

The fertilizer treatments began in 1856. We didn't put these quotes in the article, but it is clear the effects were noticed immediately. More from Lawes and Gilbert:

"So striking and characteristic, indeed, were the effects produced in this respect, that, in 1857 and 1858, the subject was thought of sufficient interest to induce us to request the examination of the plots by Professor Henfrey, to which he kindly assisted.

An endeavour was also made in the second year, 1857, to separate, and determine, the proportion of the different plants in carefully averaged and weighed samples, taken from the several plots as soon as the grass was cut."

So I was surprised that the subtitle of our article, when I saw it published, was Sometimes the value of a turfgrass management practice takes a long time to become apparent. That's not quite what we were trying to say.

40, 30, & 20

I spoke about light -- photosynthetically active radiation, to be specific -- in this presentation at the Japan Turf Show.

I was asked what daily light integral (DLI) is required for different grasses. My answer was, for warm-season grasses on putting greens, I'd look at the moving average of DLI, and I think good numbers are 40 for bermudagrass, 30 for seashore paspalum, and 20 for korai (Zoysia matrella).

If the DLI is above 40, bermuda won't have any light problems. If the DLI is less than 40, it will be a challenge. For seashore paspalum, I'd estimate that value of no problem above, and challenge below, to be 30. For korai, I'd put the number at 20. And for cool-season grasses, I guess the number is about 20 also. I base my guesses on observations of turfgrass performance in locations with varying DLI. Fortunately there is some ongoing research in this area that should give more accurate values than my guesses.

DLI values aren't always available; sunshine hours data are around -- at least the average sunshine hours data are available for a lot of places around the world. And to make a rough estimate of DLI from sunshine hours, one can estimate each hour of sunshine will give 5 moles of photons per square meter. Thus, on a day with 5 sunshine hours, one could estimate the DLI to be 25.

The climate charts at this website have normal sunshine hours data for a lot of places. To look at numbers in tabular format, the climate information on the Hong Kong Observatory website has sunshine data in an easy to view format.

On the charts I've made, I sometimes showed the average daily hours of sunshine, and sometimes the average monthly total. If daily, multiply by 5 to get an estimate of DLI. If monthly, 100 hours of sunshine gives a DLI of about 16 moles of photons per day; 200 hours is a DLI of about 33 per day; and in a month with 300 sunshine hours the average DLI would be about 49 each day.

One could, for example, look at locations such as Atlanta and Ishigaki and plot the sunshine hours for an entire year. I like to look at the combination of temperature and sunshine for each day, to see the area encompassed on the chart.

One could also display the sunshine hours on their own, with time on the x-axis.

Either way, one can see that more than half the year the sunshine hours in Atlanta are more than 200 per month, and for more than half the year in Ishigaki the sunshine hours are less than 200 per month. Looking even more carefully, it seems like Atlanta has about half the year at 230 or above, and Ishigaki has about half the year at 150 or above. From a chart like this, and a conversion of those sunshine hours to estimate DLI, one can get an idea if there is enough photosynthetically active radiation to easily manage a certain species, or if such management will be a challenge.

China and United States, temperature and sunshine

Selection_048My column in the November/December 2015 issue of GCM China shows normal temperature and sunshine data from three pairs of cities. I chose Beijing and Philadelphia to represent the cool-season zone, Shanghai and Atlanta to represent the transition zone, and Guangzhou and Tampa to represent the warm-season zone.

In each of these pairs, the temperatures are similar. In the transition zone and warm-season zone pairs, the sunshine hours are quite different, and it is the locations in the USA with higher sunshine. From the sunshine hours, one can estimate the daily light integral (DLI). As I wrote in the article:

Each sunshine hour is equivalent to about 5 moles of photons per square meter. Taking the month of May as an example, on a normal day in Guangzhou, there would be 4 hours of sunshine, in Tampa 10, in Shanghai 5.5, and in Atlanta 9. This gives an approximate DLI of 20 in Guangzhou, 50 in Tampa, 27.5 in Shanghai, and 45 in Atlanta. Bermudagrass grows best when the DLI is above 40.

Read the full article here in Chinese or in English.


Botanizing in Bangkok

One of the best places to study tropical grasses in Southeast Asia is at the Suanluang Rama IX Public Park in Bangkok's Prawet District.


The two primary species on lawns at Suanluang Rama IX are tropical carpetgrass (Axonopus compressus) in shaded areas and manilagrass (Zoysia matrella) in open areas.


If you visit the park you will notice that the carpetgrass forms a monostand under the trees, and at the edge of landscaped areas, but moving outside the drip lines of trees into areas that get more sun, the sward transitions to one dominated by manilagrass. In the photo below, one can see, just after sunrise, the manilagrass in the center of the photo holds more dew than does the carpetgrass.


This year in April, a new medicinal plants garden was established in the northern part of the park.


Medicinal plants are interesting, but what I found really exciting when I had a chance to explore this new garden is that there are much more than just medicinal plants there. In fact, there is an extensive grass collection, the largest I have seen in Southeast Asia.


For mown turfgrasses in zone 14 of the medicinal plants garden, one can see:

  • 2 types of Zoysia
  • 3 types of Cynodon
  • Paspalum vaginatum
  • Axonopus compressus
  • Stenotaphrum secundatum 'Variegatum'


There are more ornamental and forage grasses and grains than turfgrasses -- rice, sudan grass, maize, sugar cane, and scores of others.


One can find common ornamental grasses such as Pennisetum setaceum 'Rubrum', along with a lot that I saw for the first time.


In the new medicinal plants garden one can also find herbs and vegetables, and in other sections of the park there are also vegetable and herb gardens for educational purposes.

A highlight of the year is the Suanluang Rama IX Flower Festival, held from December 1 to 10 each year. I've been to this festival a few times, and the 2015 version seems the best one yet. There are even grass elephants!


These displays of horticultural art during the flower festival are reminiscent of the Girona Temps de Flors. If you can't make it for the flower festival in early December, there are still plenty of other plant collections that remain open year round. The fern and orchid houses are in a deeply shaded section of the park.


But back to the grass. As I mentioned, if you see the lawns at the park, they are primarily composed of tropical carpetgrass, as seen above in front of the fern and orchid houses, and below under the trees.


In some less shaded areas, the primary species is manilagrass. The species composition at Suanluang Rama IX park in Bangkok is the same as I've described for the lawns at the Marukatayawan Palace. One can also find Java grass (Polytrias indica) growing in patches around the park. It is usually, as shown below, found within patches of manilagrass. Polytrias indica has an inflorescence that is russet in color and this species forms a distinctive component of the sward because of this coloration.


One can also find Chrysopogon aciculatus and Paspalum conjugatum mixed in with the Axonopus compressus in some places. The leaf characteristics of those three species are similar, and it is only obvious that all three species are present when the plants are flowering. These grasses on the lawns at Suanluang Rama IX park and in the grass collection of the new Medicinal Plants Garden are typical of the grasses that grow and are used in South and Southeast Asia. Well worth some study if you care about these things.

Even if you don't care much for botany or agrostology or grass elephants, I would still recommend a visit. This is the freshest air in the city and the park is popular for running, walking, cycling, boating, birding, tai chi, yoga, and aerobics.


Turf on Twitter

Bill Kreuser asked how many in the turf industry are on Twitter. As of this week, it seems to be a little more than 20,000.

John Kaminski suggested looking at accounts with a large number of followers to get an estimate, which is about 9,000.

I pointed out that one should not just count followers, but should make sure they are from real accounts. Some fake accounts have distinctive characteristics in the follower to following ratio, and in the number of tweets, that make them easy to identify.

John Smart suggested that we should look at The IOG and BIGGA accounts too, rather than only US-based accounts.

Taking this approach, one would want to find all the followers of the accounts of interest, and then count the unique followers, since one account may follow for example both @TurfDiseases and @BIGGALtd.

Using the twitteR package in R, I got the follower lists for these accounts:

I then combined the lists, which gives a total (as of follower lists obtained during the week of Nov 30) of 48,203 followers. But they are not unique, because many followers follow more than one of the above accounts. Selecting only the unique followers, one finds this:

  • There are 23,928 unique accounts following those turf accounts listed above.
  • There are 22,595 unique accounts that have sent out at least one tweet. That is, their statuses count is > 0.

A lot of those accounts will be rarely used or inactive, but to make those estimates, I leave as an exercise to the reader.

The code I used is here. You'll need to put in your own API key and access token information.