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February 2015
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March 2015

Rhubarb, Custard, and the Little Green Book

I'm planning to do a better job of coming up with good titles for articles and presentations. The modern master of titles may be Henry Bechelet, who wrote an article about aeration entitled "Rhubarb and Custard." That sure beats "Aeration" as a title, doesn't it? You'll find the Rhubarb and Custard article in the little green book, the 80-page STRI Disturbance Theory by Bechelet and Windows. I brought a copy of the book on a recent trip and enjoyed re-reading it.


The first chapter is a reprint of Changing the Nature of Your Greens. Bechelet begins the article describing just what the disturbance theory is:

"The objective of this article is to give a greater understanding of the survival strategies developed by the individual turfgrass species ... I mean to get you thinking about your greens differently.

This article is adapted from the work of Grime, Hodgson, and Hunt in their study: 'Comparative Plant Ecology - A functional approach to common British species' (1988). This work states that the vegetation that develops in a place at a particular time is governed by environmental pressures. These pressures may be categorised as stress, disturbance, and competition and they can vary in their relative intensities."

For more about these plant strategies, see Grime.

The third chapter is a reprint of Food For Thought. This is a common sense approach to turf nutrition. Bechelet writes:

"We want to minimise fertiliser inputs to reduce the need for incessant aggressive treatments [disturbance]. Minimal (some would say 'optimal') means producing just enough growth for the surface to be prepared and be able to withstand play without deteriorating. The desired level of growth will vary depending on what we need to achieve at different times of the year ... In terms of nitrogen input, for soil-based greens the Danish experience finds 5 - 7 g/m2 N per annum to be sufficient. You should aim to apply as little as necessary so you don't have to verticut too often."

Just to check how the growth potential model would relate to the "Danish experience," I calculated the temperature-based growth potential for Copenhagen, using normal temperature data, and for fine fescue I would use a maximum monthly N of 2 g/m2. The growth potential model predicts 6.5 g annual N for Copenhagen. Right in the range suggested by Bechelet.

For more about growth potential, listen to Frank Rossi and I talk about it on TurfNet RADIO.

"Can you send me anything that explains the differences between matrella and japonica?"

I sure can. The first thing I look at for different species is the Kew RBG GrassBase. Here are the entries on Zoysia matrella (manilagrass) and Zoysia japonica (japanese lawngrass).

Both are perennial, mat forming grasses. When they are mown, the visual distinction is in the width of the leaf blade. The manilagrass leaf blade tends to be 1 to 3 mm in width; the japanese lawngrass blade is wider, from 2 to 5 mm. There are other distinctions, but the main one is simply how fine or how coarse the turf is.

Zoysia japonica mown at 15 mm

Above is japanese lawngrass, and below is manilagrass. These grasses were grown on the same soil, near Bangkok, with the same fertilizer and mowing and irrigation. The visual difference one sees is in leaf blade width.

Zoysia matrella mown at 15 mm

These photo galleries of manilagrass (Zoysia matrella) and japanese lawngrass (Zoysia japonica) show more distinctions between these species, as well as their appearance and use.

The other big difference in the species is their area of adaptation. Japanese lawngrass is more cold tolerant, and generally grows in places where there is a winter and the grass goes dormant. Manilagrass is a tropical grass, native to areas where the grass does not go dormant. As a turfgrass, manilagrass can be used in locations where there is a winter. But in places with winters colder than Tokyo, there is some risk of winter damage on manilagrass, while japanese lawngrass could still tolerate those winter temperatures.

Frankly Speaking about growth potential & turf nutrient use on TurfNet RADIO

Frank Rossi and I spoke on TurfNet RADIO about the temperature-based growth potential and how it can be used to predict turfgrass nutrient use. Listen to our conversation here.

Check Out Science Podcasts at Blog Talk Radio with TurfNet RADIO on BlogTalkRadio with TurfNet RADIO on BlogTalkRadio

During the conversation, we discussed these documents. Links to view or download here:

Calculating how much of an element is applied in a liquid fertilizer


I received this question, and thought it might be of general interest. In fact, I had to look up the answer myself, just to be sure:

"I was wondering when using the MLSN Guidelines how to calculate how much of a specific nutrient you are applying in a liquid fertilizer?"

I replied:

In a liquid fertilizer that is pre-mixed, I think the % given is by mass, and not by volume. So you need to take that % and then correct for it based on the density of the particular fertilizer you are using. That info should be on the label, lbs/gallon or whatever, and then you make the conversion to figure out how much you are putting out per unit area of turf.

Method explained here:

Look at this Grigg Bros product, for example:

It is 0.4% manganese by weight. And 1 gallon of this fertilizer is 10.68 lbs. So if you apply at the 6 oz/1000 rate, that is going to be (this is where I remember how convenient metric is!):

128 fluid ounces in 1 gallon, so 128 fluid ounces is 10.68 pounds

10.68 / 128 = 0.083 lbs of product per 1 fluid oz

0.083 * 6 = 0.498 lbs of product (I'll round up to 0.5) going down per 1000 ft2

For the manganese rate, it would be 0.5 lbs * 0.004 = 0.002 lbs Mn/1000ft2

Out of curiosity, the N (4% in this product) at the 6 oz rate would be 0.5 * 0.04 = 0.02 lbs N / 1000

Surprises, conservatism, and what one can learn from soil testing: part 2

I wrote about three things one can learn from soil testing in this post. Here, in part 2, I discuss four more things related to this subject.

The seashore paspalum plots on the driving range tee at Siam CC Waterside Course.

4. Grass can grow well and produce a high quality surface across a range of soil chemical conditions. Don't forget the importance of light, water, soil air, and mowing. By comparison, soil nutrients are simple, and there is more leeway for variation in soil chemical properties. These plots were very low in calcium and magnesium by any interpretation, had potassium above the MLSN guideline but lower than conventional guidelines, and the pH of the plots was from 4.9 to 5.5. Even with these conditions, the grass is good.

5. Sand is a horrid growing medium for plants. The CEC is really low, the micronutrients are low, the accumulation of organic matter that is so beneficial in a normal soil actually causes problems with a sand, the pH is usually not well-buffered -- there are a lot of things not to like about sand as a nutrient supplying medium for turf. The soil tests on these test plots show this.

6. Available nitrogen (nitrate + ammonium) was pretty much the same for each plot, no matter the N source supplied (or not). There was 8.7 ppm N in the control plot that received no N, 8.3 ppm in the urea plot, 7.2 ppm in the 19-0-19 plot, and 6.3 ppm in the 15-0-26 plot. It is interesting that the control plot actually had more N than the plots that received N fertilizer. One would need to run a lot more samples to determine if this was just by chance, or if there is some cause for this -- a difference of 2 ppm in real terms is tiny. What we saw at the field day was grass that looked pretty much the same, no matter the fertilizer. When the conditions are right for mineralization, and when there is enough organic matter in the soil, N fertilizer may not be required. The control plot here looks just as good as the plots that received N, and the soil N was pretty much the same in all the plots.

The plots at the field day all had similar color, indicating that the nitrogen supply to the grass was similar in each plot.

7. For many nutrient experiments, it is difficult to see treatment effects when they are not done under controlled conditions. There were visual differences between the plots a month before the field day, after the first application of fertilizer treatments. But management of the turf, especially the irrigation applied to make sure everything looked at its best for the field day, seems to have increased N mineralization in the control plot and thus all the grass was supplied with enough N and K no matter the treatment. Doing experiments under controlled conditions is an easier way to detect small differences in treatment effects, if those treatments have only a small effect.

These demonstration plots were set up to use as a discussion point for the experiment about N:K ratios conducted under controlled conditions, described in this poster, this handout, and in these slides.

Monthly Turfgrass Roundup: February 2015

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

Jason Kruse asked about micronutrients and it turned into a long discussion.

Silica and green speed. Who would have thought it such a controversial topic? Follow-up discussion on Facebook and Twitter.

Using and misusing the word fertility.

Double wide fairway stripes look great:

More double wide stripes at Monterey Peninsula CC:

Diversity of opinion, factual matters, and soil tests.

Sod bunker liners, a "popular option in our area of the country."

Frankly Speaking with Dr. Rossi about turf nutrition on TurfNet Radio.

A fast way to do root pruning:

MLSN, all nutrients, and why we don't have MLSN guidelines for micronutrients.

Adam Garr asked about morning sun, and that also turned into a long discussion.

A Pitchcare discussion about soil testing.

This was a popular sentiment:

What about nutrients in the soil that are not available? I answer that question three times.

Sodium as an imaginary problem on sand-based putting greens.

Soil tests and fertilizer calculations -- are we on the same page?

Slides, and a handout, on irrigation & 3 key points for summer.

Soil tests and N rates.

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.

Surprises, conservatism, and what one can learn from soil testing: part 1

Last week at the Siam CC Waterside Course, I talked about N:K ratios on a seashore paspalum tee. I showed some demonstration plots, on which had been applied two applications of these products, with the application rate being 5 g N/m2 at each application, for the products that contained N:

  1. nothing (control, no N or K applied)
  2. urea (46-0-0, a 1:0 N:K ratio)
  3. 19-0-19 (1:1 N:K2O ratio)
  4. 15-0-26 (~ 1:2 N:K2O ratio)
The seashore paspalum test plots at the Field Day last week with collaborating scientists from the Thailand Institute of Scientific and Technological Research

We collected soil samples after the first application of fertilizer treatments, and before the second, and sent them to a lab for analysis. Unfortunately, the results came back to me the day after the Field Day, so I wasn't able to discuss them there. But the results were illustrative of a some points about soil testing I would like to make anew here, and others that I'd like to reiterate. I'll start with three in this post.

1. One really should do soil tests on a regular basis. I suggest once a year will be sufficient frequency for the average facility. If tests are not done, there is no way to know the conditions in which the grass is growing. On the tee where we had these demonstration plots, the soil pH ranged from 4.9 to 5.5; I suggest maintaining soil pH at 5.5 or above in most cases. And in these demonstration plots, the soil calcium (Mehlich 3 extractant) ranged from 155 to 246 ppm, way below the MLSN guideline of 331 ppm. And the magnesium in the soil (Mehlich 3 extractant) was even lower, from 25 to 41 ppm -- all demonstration plots were way below the MLSN guideline of 47 ppm.

I demonstrate how we can trim turf in pots to a simulated fairway height on this seashore paspalum growing in soils with low pH and Ca and Mg well below the MLSN guideline

2. The MLSN guidelines are conservative. I've mentioned that before, and this is a good example of that conservatism. If you were at the Field Day last week, you saw that the seashore paspalum on that driving range tee looked pretty good. If you weren't there, you can see from the photos (provided courtesy of Dr. Rujira Deewatthanawong) above -- it looked green, actively growing, divots filling in quickly, a dense sward -- the turf was performing well and did not appear deficient in any nutrients. Yet the soil calcium and magnesium were both below the MLSN guideline. One meaning of conservative is "(of an estimate) purposely low for the sake of caution." In the case of nutrient guidelines and the resultant fertilizer recommendations, we want to avoid a deficiency, so we could say also that an estimate is purposely high for the sake of caution. That is, a conservative estimate is one that errs on the side of caution.

Soil tests are used to determine how much fertilizer should be applied, and the MLSN guidelines are set in such a way that for the sake of caution the amount of fertilizer recommended will be more than the grass actually requires. One of the concerns that has been raised is that perhaps the MLSN guidelines are too low. Read more about those concerns here:

 This driving range tee, at which the grass performance was fine, but soil Ca and Mg were way below the guidelines, is an excellent example of this conservatism. One can look at the turf -- Ca and Mg aren't really required as fertilizer here, because the grass performance is fine, and the soil is supplying enough of those elements to produce high quality turf. But using the MLSN guidelines to calculate the fertilizer requirement, I would recommend application of 25 g Ca m-2 (5 lbs Ca/1000 ft2) to supply enough Ca to reach the MLSN guideline. And using the MLSN guidelines to calculate a Mg requirement, it would be 5 g Mg m-2 (1 lb Mg/1000 ft2). That's what I mean by conservatism. Even though the MLSN guidelines are way lower than conventional guidelines, it is the conventional guidelines that are set almost impossibly high. The MLSN guidelines are much lower, but they are still conservative, in that for the sake of caution they will recommend application of elements that are unlikely to cause an improvement in turf performance.

3. Supply of nitrogen (N) really controls nutrient demand. This is embedded into the fertilizer requirement calculations that one makes when using the MLSN guidelines. And the fertilizer treatments and amount of K applied and remaining in the soil in these demonstration plots illustrates that demand.

In the control plot, where no N or K was applied, the soil K (Mehlich 3 extractant) was 62 ppm. In the plot to which urea was applied, the soil K was 41 ppm. Why was it lower? Well, because the added N stimulated growth and increased the grass demand for K. And in the plot receiving the 19-0-19 fertilizer, the soil K was 48 ppm. How can it be, that a plot receiving a 19-0-19 fertilizer would have a lower soil K than the control plot? It's because adding N increases the uptake (root uptake = soil depletion) of K. It was only the 15-0-26 plot that got soil K elevated above the control plot, to 71 ppm. Of course, we didn't see much of a difference between the plots, on the surface -- all the turf looked good, and looked pretty much the same. But in the soil, there were differences, and they were related both to how much K had been applied to the plots, and also, whether N had been applied. Those data are plotted below, and the color of the points indicates whether N was applied to that demonstration plot, or not.


N:K ratios on warm-season grass

At the Sustainable Turfgrass Management in Asia 2015 field day, I spoke about nitrogen to potassium (N:K) ratios as applied to manilagrass, bermudagrass, and seashore paspalum.

We showed this poster, describing an experiment conducted in Thailand, and also showed fertilizer test plots on a seashore paspalum driving range tee.

For more information about this project, see this handout on Fertilizer & N:K ratios.

Does sandcapping affect playability? And does species selection?

I get to talk about two of my favorite topics today. In our 1 day seminar on designing, building, and maintaining golf courses, course architect Paul Jansen will be speaking about 3 main topics:

Where do I come in? I'm going to hone in on the ground contours part, and discuss how the soil and grass conditions affect how a ball will bounce and roll. One can design and build all these great features, but if the sward isn't right, the playability won't be either.

A quick summary of my thesis is this -- sandcapping ain't so great because once one introduces a sand profile, the organic matter must be managed or it will fail. That happens by default for putting greens -- usually -- but almost never on 10++ hectares of fairway turf. And using grasses that don't die allows one to apply less N and water. That leads to firmer surfaces that are better to play on when one wants ground contours to be interesting.

Here are three ways to follow along.

First, my presentation slides are here:

Second, I shared a 2 page PDF handout at the seminar. Download it here.

Third, the above slides and PDF, along with links to all the articles and the video from the presentation, are in this online handout. For convenience, I reproduce all those links here: