Turfgrass Information

"Knowing which soil test results are important can simplify turf management"

Kreuser_soil_test

Bill Kreuser's guide to soil test interpretation; read it! Here's how he describes it:

"While soil tests can be useful, their results are frequently overanalyzed and overinterpreted. Sometimes soil test results can be more confusing than helpful. It doesn't have to be so difficult. The goal of this publication is to explain which soil test values are important and which values can be ignored."

After reading the publication, I think it achieves that goal.


One to add to the reading list

Jim Brosnan's article from last week's Green Section Record is one you will want to add to the reading list, and after reading it, to your reference file. Entitled Golf's Most Common Weed-Control Challenges, Brosnan gives an overview of the particularly problematic weeds and the most current information about their control -- especially for warm-season or transition zone areas.

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For more information about weeds, see the University of Tennessee's Turfgrass Weeds site.


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.

Books

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.


Increasing roots on putting greens

Selection_061The latest issue of GCM China is fresh off the presses, and it includes my article about four ways to optimize the root system on golf course putting greens.

The article is available in both Chinese and English.

What did I suggest?

Mow the grass as high as possible, apply the right amount of N at the right time, make sure there is plenty of air in the soil, and avoid P deficiencies. Read the article for full details.

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Penn G-2 creeping bentgrass in Shanghai

Frankly Speaking about turfgrass nutrition, the MLSN guidelines, & the GSS on TurfNet RADIO

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

I had a chance to talk with Frank Rossi tonight on TurfNet RADIO. We discussed turfgrass nutrition, soil testing, the MLSN guidelines, the Global Soil Survey (GSS), and not much else. But Dr. Rossi has a way of asking interesting questions, and I tried my best to answer them in a way that makes sense. Have a listen to our discussion and see if we succeeded!

For more information about the things we discussed, here are direct links:


Soil moisture and irrigation: 3 key points for summer

In my second presentation at the Ontario Golf Course Management Conference, I discussed three things about soil moisture and irrigation that may lead to improved turf conditions in summer.

More discussion below, but first the handout, and these slides.

The first thing I discussed was irrigation frequency. I explained that daily irrigation can be used to keep the soil drier, and with a higher air content, than deep and infrequent irrigation. This annotated chart explains how lower soil moisture can be the result when irrigation is supplied daily.

Then I talked about water quality, and I finished the presentation explaining how a soil moisture meter can be used to estimate the relative evapotranspiration at differing environments on a property.

I didn't include any discussion of wetting agents in the presentation, but I would have talked about this if there was more time. Data show there is no such thing as wetting agents that retain more water or move water through the soil. Understanding what wetting agents really do is important to make the best use of these products.


Nonsense, facts that aren't facts, and turf in 3 dimensions

I received this inquiry about nutrient application and soil nutrient concentration:

I have in mind that somebody wrote that one rise any element by 6.7 ppm when it is applied by 1g/m². Is that true or is it different for any element so that i have to change the factor in my calculation?

This 6.7 ppm factor is correct when thinking of the turf system in 3 dimensions. How does this work out? It is like this. Assuming a rootzone depth of 10 cm, and a soil bulk density of 1.5 g/cm3, then the mass of the rootzone in 1 m2 is 150 kg. An application of 1 g/m2 of an element to the surface, assuming distribution throughout the rootzone, is going to cause an increase of 6.7 ppm (1000 mg/150 kg). Likewise, nutrient harvest can be estimated in the same way.

If you like to use other units, or a different rootzone depth, or have a soil with a different bulk density, the calculations are elementary.

I've written before about the ease of such calculations using metric units. The calculations can be made in other units, but I find it especially easy to visualize these in 2-dimensional and 3-dimensional space using metric units.

Being familiar with 2-dimensional and 3-dimensional thinking can help to pick out nonsense pretty quickly. Here are two examples.

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I saw this tweet about a cubic mile of fog being made up of less than a gallon of water. That just didn't sound right at all. This is a 3-dimensional space we are thinking of, and I remembered that in non-foggy conditions, I'd read one can get up to half a liter of dew in 1 m2 with the amount of  water in a column of air something like 10 to 50 meters high. I'd read this in Nobel's Physicochemical and Environmental Plant Physiology, and looked it up again, and it turns out that at an air temperature of 10°C, the column of air would need to be 53 m high to provide that much water. My memory wasn't exactly right, but now I had the basic information I needed.

Now obviously, 53 m3 is a hell of a lot less than a cubic mile. One cubic mile is about 4,165,509,529 m3. Roughly estimating that a half liter of water is slightly more than an eighth of a gallon, one can calculate that there are 78,594,519 units of 53 m3 in a cubic mile, each with potentially an eighth of a gallon of water, so in a cubic mile of fog there may be something like 9,824,315 gallons. This is easier if one just keeps it all in metric units, but the point is, being aware of what the volume is, one can think in 3-dimensional terms and get a rough estimate of just how outrageous such a statement of less than one gallon of water in a cubic mile of fog is.

One can find other estimates, such as 56,000 gallons of condensed water in a cubic mile of fog. I prefer to consider the total amount of water, and that obviously is way way more than a gallon.

There was also the estimate of how the length of roots in a lawn was supposedly extending to a distance equivalent to 15 round trips between the sun and the earth.

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That just sounds outrageous from the start, for anyone who has seen turfgrass roots, an average lawn, and has some idea of how far the sun is from the earth. Even with generous estimates of root length, and including root hairs, the cumulative root distance falls well short of even a one way trip to the sun. Thinking in 2-dimensional and 3-dimensional terms makes these estimates easy.

So whether one wants to know a simple conversion between nutrient uptake and depletion from the soil, fertilizer addition and increase in the soil, water application and increase in soil moisture, plant water use and decrease in soil moisture content, or expand this to consider whether nonsense "facts" can possibly be true, thinking about turf in 2 and 3 dimensions can be useful.


"This publication is intended for professional turfgrass managers who use fungicides as part of an overall disease-control program"

Selection_009"This publication" is Chemical Control of Turfgrass Diseases 2015 by Paul Vincelli and Gregg Munshaw. A wealth of information about diseases is packed into only 24 pages.

And it is not just about chemical control. Common turfgrass diseases are described, the environment and season in which the disease is most likely to occur are explained, and the best control measures for each disease are given. There are also informative sections about fungicide resistance, improving spray efficacy, detrimental effects of pesticides, and much more. This is a guide that will be of use to every professional turfgrass manager.


The TGIF Database: open to all this week

TgifI use this almost every day. When I am studying something new, I may access the Turfgrass Information File database multiple times per day. When I was a student, I had access through the university. One of the first things I did when I graduated was to purchase a lifetime subscription, to ensure I would always be able to access the information in this database.

You probably already have access, because if you are a turfgrass professional, you really should be a member of at least one of these organizations that provide access to the database as part of their membership benefits package.

Orgs

For this week only, even if you are not a subscriber to the database or a member of a cooperating professional organization, you can experience the database full of turfgrass information to celebrate its 30th anniversary. See the details at the login page.

And not everyone realizes this, but much of the information indexed in the database, including full text turf books, a searchable database of every Green Section Record article, and much more, are available free whether one is a subscriber or not.