A little more data to support an anecdote

Yesterday I wrote about soil organic matter decreasing over a 3 year period, even though the greens had only been cored twice in that time, and sand topdressing amounts had been reduced each year.

17th green after coring in May 2013

When I think about reducing organic matter, I usually think of removal or dilution. Removal would be through coring or scarification; dilution would be by mixing sand with the organic matter.

12th green after 12 mm core aerification and topdressing in May 2013

But in this case, I think the organic matter in the soil is going down because the organic matter production is less than the organic matter decomposition. The reason I think this is simple. There hasn't been much removal or dilution of organic matter in the past 3 years, but the organic matter has still gone down.

The 14th green in August 2013

In the comments to yesterday's post, there was some discussion of layering if sand was not applied often enough. I agree that undesirable layering might occur, but only if the grass was producing organic matter faster than it was decomposing.

To put this into context, I added up the volume of clippings from the greens in 2015, to give some idea of the growth rate at which the maintenance work described yesterday has led to a decrease in soil organic matter.


Add that up for the year and it is 270 L/100 m2. Measurements of the fresh weight of clippings on these greens give 0.3165 kg for each liter of clippings, so that is 85 kg of fresh clippings per 100 m2. I expect these clippings are about 70% water and 30% dry matter, so I've estimated the dry weight of the clippings at 26 kg/100 m2.

That gives three estimates of how much the grass is growing at this location. Those numbers might be useful if you'd like to compare the growth of grass where you are.

As an aside, these types of calculations are how I estimate nutrient harvest. If you've been to one of my seminars about how to use the MLSN guidelines, I will have described that the use of the guidelines involves taking the amount the grass will use (I'll call that a), adding that to the amount I want to make sure remains in the soil, which is the MLSN guideline (I'll call that b). These values a and b, together, are the amount of an element we want to be sure is present. a + b represent the amount we want to have. The amount we actually have is measured by the soil test, and I call that c. It follows that the amount of an element required as fertilizer is the amount we want to have, minus the amount we do have, represented in an equation as a + b - c.

Data to support an anecdote

Last week I received the latest soil tests from Keya Golf Club, where Andrew McDaniel is the superintendent. I'm sharing the organic matter results from the greens, because I think they will be of general interest. This chart shows the soil organic matter % on the greens for samples taken in early 2013, 2014, 2015, and now 2016.


Now for a bit of a tangent, and then back to the work that's been done at Keya since 2013. It would seem that not core aerifying, and not topdressing all the time, would be considered alternative maintenance. Another way to look at it is that the management of soil organic matter -- the amount of work required in that regard -- will be proportional to the growth of the grass.

I remember a conversation I had once during break time at a seminar in New Delhi. "Tifeagle and other ultradwarf bermudagrass varieties accumulate too much thatch," someone told me, "and will require almost constant and aggressive verticutting to keep it under control." I disagreed, pointing out that the amount of thatch (organic matter) control required will be related to how much the grass grows. "Tifeagle in Siberia won't produce any thatch at all," I said.

As an example, this is Zoysia japonica in late July in Yorkshire, surrounded by cool-season grasses. The zoysia is not producing much organic matter at all, and there's no need to verticut or topdress or core.


Another example: this is Penncross in Thailand. It germinates, but doesn't require mowing. If you can keep it alive, you certainly don't have to worry about organic matter management.


Rather than prescriptive recommendations of surface area to be removed by coring (I've recommended this in the past) or the quantities of sand that should be applied as topdressing (I've also recommended this in the past), I now think it is more reasonable to consider the growth rate of the grass, and to manage the organic matter as required based on the growth rate.

Ideally, there will be no coring, minimal verticutting, and minimal topdressing. That's easier, and it causes less disruption to the playing surface. Such an approach may not be possible, but I prefer to have my ideal as great surfaces all the time, with minimal disruption, compared to the alternative ideal of great surfaces except when coring to remove x % of the surface area each year while applying a total of y mm of sand per year.

Back from that tangent to the greens at Keya, where the organic matter on greens has been going down since 2013.


If one does a regression on these data, for each day that passes, the organic matter in the top 10 cm of the soil has gone down by 0.005 g per kg. In 365 days, the reduction is about 1.8 g/kg.

Here's where the data support an anecdote. The anecdote is, managing the growth rate allows one to minimize or eliminate coring.

The N rate on these greens in 2013, 2014, and 2015, respectively, has been 14.6, 9.5, and 10.6 g/m2. That is still enough to produce a dense korai turf (manilagrass or Zoysia matrella).


Coring and solid-tine aerification has been minimal and has decreased while the greens have only improved. 12 mm core in May 2013, 12 mm solid in July 2013, 12 mm core in June 2014, and 13 mm solid cross tine in July 2015. That's not much, and the organic matter is going down.


Greens were verticut 3 times in 2013, 3 times in 2014,and 4 times in 2015.

Topdressing amounts have been 8 mm in 2013, 4.6 mm in 2014, and 3.8 mm in 2015.

You see the trend? Core aerification is done infrequently, sand topdressing is applied less and less, N fertilizer is applied at a reasonable rate, and the soil organic matter goes down. It's a viciously good cycle.

New pace of play manual from The R&A

The R&A have produced a pace of play manual that I enjoyed reading this week. From the overview:

"If a golf club or facility has identified that it has issues with pace of play, it is The R&A’s strongly held view that there are solutions available that can improve the situation. With this in mind, The R&A has produced a Pace of Play Manual that pulls together a wide range of potential solutions."

Read the manual online, or download a pdf copy here.

Another interesting technique to modify fairway conditions

I've seen introduction of seashore paspalum to bermudagrass, and manilagrass to bermudagrass, by hand planting the introduced species into slices cut into the exisiting turf. This post shows seashore paspalum planted into a bermudagrass fairway using that technique.

I've also seen resodding to convert to a different grass, but in a way that doesn't require course closure.

At PGA Catalunya, hybrid bermudagrass was introduced into the creeping bentgrass fairways. These photos show the fairways in 2016, five years after the bermudagrass was added.


The idea was to improve fairway conditions in summer with the bermudagrass, due to the poor irrigation water quality. I've been impressed with the fairway conditions at PGA Catalunya, and also with the technique used to introduce the bermuagrass. These videos of the technique are shared on course superintendent David Bataller's YouTube page.


What technique was used at PGA Catalunya?

First, simulated divots were made in the bentgrass fairways using an aerifier fitted with custom "tines".

Second, a rotovator or landscape tiller was used to make a divot mix from certified Tifway 419 sod and sand.

Third, the divots in the bentgrass fairways were filled with the bermudagrass divot mix.

The result is improved fairway performance during the summer, due to the presence of bermudagrass. And with this technique, the improvement was accomplished rapidly, without closing the course, and used a relatively small amount of purchased sod.


Shade and sun

Shade from trees will often reduce the photosynthetically active radiation (PAR) by about 80%. For example, the area in full sun on this green had a photosynthetic photon flux density (PPFD) of 749 micromoles of photons per square meter per second.


An adjacent area on the same green, but in tree shade, had a PPFD of 139.


It is possible to make a good estimate of the effect of shade, and to know just how much PAR is reaching the turf, without using a meter. Take this putting green, for example, with part of it in sun and part in tree shade.


The PPFD in sun (with no clouds) can be estimated by knowing the day of the year, the time of the day, the latitude, and the longitude. This Shiny app makes the calculation based on those inputs. The calculated PPFD by that app is pretty close to the measured PPFD. Here are some calculated PPFDs compared with measured PPFDs from sites in full sun, unobstructed by clouds.


If you are in full sun with no clouds, then you can get a good estimate of PPFD from the app.

If there is tree shade, I'd assume that the PPFD in shade is 20% of that in full sun.

If there are clouds, I'd look for my shadow and look for the sun, to get an estimate of how much the clouds are reducing the PAR, as described here.

Avoiding nutrient deficiencies

Selection_052That's the title of my column in the May-June issue of GCM China. I described two ways to ensure there are no nutrient deficiencies.

One way is to find the quantity of elements in the soil by soil testing. Then one can supply enough of each element to ensure the quantity in the soil remains sufficient to supply all that the grass can use.

A second way, if soil tests are not conducted, is to make a conservative estimate of how much of each element the grass will use, and then to supply that amount as fertilizer. I prefer the first approach that utilizes soil testing, because in almost all cases the first approach will result in more efficient use of fertilizer.

The article is available in Chinese and in English.

For more about the first technique that utilizes soil testing, and the MLSN guidelines I recommended, see Just what the grass requires (this is the Chinese version of the same article).

All 14 articles I wrote for this GCM China  (turfgrass talk)  series are available in book form in A Short Grammar of Greenkeeping.

How to save 82% on fertilizer cost

There is another good article in the Green Section Record, this one by Blake Meentemeyer and Brian Whitlark on Turfgrass Fertilization. You'll want to read the full article. It talks about the overall goals of fertilizer application, soil tests, some myth busting, fertilizer and playability, and more. It's a modern article with a lot of historical references too.

The most interesting part of the article for me was the economic case study. A course reduced the putting green fertilizer cost by 82% and the result was "the putting greens have never been healthier."

For more about this topic, see How to save 60% or more in turfgrass fertilizer cost.

Monthly Turfgrass Roundup: April 2016

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

This one's from 2012, actually, but it got a ton of views this month. Doug Soldat's photo of dandelions in ryegrass but not in tall fescue.

Also from Soldat, and available in the TurfNet webinar archives, Is your potassium program hurting or helping your turf?

Pat Gross and Chris Hartwiger on how to develop a water budget for a golf course.

Jason Haines on controlling growth rates.

Visualizing climate differences.

Grass selection by normal temperature and sunshine.

Haines on reasons to not aerate in spring.

PACE Turf suggested reconsidering the use of tissue nutrient analyses as a guide for fertilizer.

This led to an extensive discussion, summarized by Pam Charbonneau in To tissue test or not to tissue test?

Todd Lowe wrote about alternative aeration practices that help reduce golfer frustration without jeopardizing turf health.

Haines spoke at a seminar and heard someone say he's starving his greens. Is he?

Nutrients adequate but not available. Is this the most common oxymoron in turf?

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.

MLSN, a pet peeve, and algae

Selection_046These things are not usually connected. But for this post, they are. Please bear with me.

I was glad when Jason Haines shared his slides from the WWGCSA meeting in January. His talk was entitled 4 years of MLSN (And my greens still aren't dead). That's great news on two fronts -- that the greens aren't dead, and that the slides were shared.

I wish everyone would share their slides and handouts. All through the year, but especially in the winter, it seems, there are turfgrass seminars happening all around the world. We could all learn faster, bad ideas could disappear faster, and good ideas could disseminate faster, if more of the information were made available.

You'll find most of my presentation slides on my Slideshare and SpeakerDeck pages. Additional slides and handouts, a lot of them mine, are on on this blog at the www.blog.asianturfgrass.com/seminar tag.



Where does algae come in to this? John Kaminski (and John Inguagiato) have a really good presentation on Algae Management for Golf Course Putting Greens on SlideShare.

When I think of sharing information, that's what I'm talking about. I'm glad Jason and John shared these presentations, and I wish this was the norm.

Roots, growth potential, and fertilizer

Last month Bhupendra Singh shared this photo of roots on a Tifdwarf putting green in New Delhi.


Growing roots! Tifdwarf at Peacock Course Greens, Delhi Golf Club.

A photo posted by Bhupendra Singh (@bhupendra.golf) on

I wondered how the grass had been managed for the past six months.

Here's the high and low temperatures in New Delhi from November 1 until April 9. Delhi_temperatures
Those temperatures, converted to a C4 growth potential (GP), show that the GP was low in winter and approached a maximum as the temperatures warmed in the spring. Delhi_gp
So was there anything extraordinary done to develop roots like this?

Bhupendra informs me (and sent along those photos to confirm the results) that the N sources have been ammonium sulfate, urea, and potassium nitrate. The P source is single super phosphate, and the K has come from potassium nitrate and potassium sulfate.

The application rates have roughly tracked the GP.

In the winter, N was applied at an average of 0.5 g N m-2 mo-1. In February and March, as the grass came out of dormancy and the GP approached 1, the N rate has been 3 to 4 g N m-2 mo-1. The P and K are applied in proportion to the amount of N applied, in the approximate ratios used by the grass.

The mower bench setting was 4.25 mm in early April when the photo was taken, with a 3 mm prism reading on the ground.

These are new greens, planted in autumn 2015.

Even for new greens, those are still pretty impressive results. Sure, one doesn't putt on the roots -- what really matters is the surface. But these photos demonstrate that supplying the grass with the nutrients it can use, at the time when net photosynthesis is at its highest, and given water and air in the soil, roots are going to grow.