A humorous, numbered, and long one: "I'm not an enthusiast for diversity of opinion where factual matters are concerned"

I'm going to throw all kinds of things together here.

1. This post on Pitchcare shows that there is a diversity of opinion about turfgrass nutrition and the interpretation of soil tests.

2. I received a question about that particular post, tried to answer it here, and it ended up being quite a lengthy discussion on a range of topics (see the comments section at the bottom too).

3. My approach to turfgrass nutrition specifically, and turfgrass management generally, is that it is simple, but not easy; if we can identify the principle factors influencing turfgrass performance, and modify them, we will be making great progress toward our goal of producing the desired turfgrass surfaces. When it comes to turfgrass nutrition, I suggest making sure that soil nutrient levels are kept above the MLSN guideline levels.

We are very open about how we develop these guidelines, which data are used, what our assumptions are, and we even share the code we use to generate the guidelines. We study this topic intensively, and we only recommend or suggest nutrient application when we are confident it will have an effect on turfgrass performance. This approach reminds me of these comments by Richard Dawkins on facts vs. opinion:

I don't give a damn for anybody's opinion; I only care about the facts. So I'm not an enthusiast for diversity of opinion where factual matters are concerned.

Watch/listen to Dawkins here.

4. I spoke with Frank Rossi on TurfNet RADIO about turfgrass nutrition and nutrient guidelines. This conversation is about facts, and doesn't give a damn for opinions. If you do turfgrass maintenance, you should be aware of what we talked about.

5. I've been writing here since January of 2009, and I've never mentioned BCSR. I make an exception today, to share this point by Max Schlossberg (with counterpoint from Joel Simmons) about how soil tests are done and interpreted and how fertilizer recommendations are made.

Max has an account on Twitter now. I'm excited about that because he has great insight to share about turfgrass nutrition. And a lot of other things too, but I'm especially counting on him to correct me when I err.

6. Turf nutrition doesn't have to be that complicated. Turf maintenance in general doesn't have to be that complicated. You can think it is complicated if you want to. I take the approach that we try to modify the growing environment of the turfgrass to create the desired playing surface, and we take special care to control the growth rate of the grass. If we do those things, which in principle are simple, but which in practice may require a lot of work, we achieve the desired turfgrass conditions.

I am not going to rewrite all on these topics here. If you are interested, read more of the other posts on this blog. But please do contrast the simplicity of the approach I describe, and the MLSN approach, to the more complicated description here:

And it continues here:

Actually, those complicated descriptions of nonsense weren't about turfgrass fertilizer. But you may have heard or read descriptions of turfgrass products and maintenance that were approaching that level of complexity. It really shouldn't be like that.

7. Everyone probably knows about Occam's razor. I had a great discussion about this with John Bladon last month. If you don't know what this is, you can read about it here.

Soil Tests and Rates of Nitrogen Fertilizer

Beth Guertal's excellent webcast on "Fact, Myth, and Legend in Soil Fertility" (watch on Turfnet here) starts with facts and myths about nitrogen. One of the facts is this one -- N fertilizer rates are not based on the amount of N in the soil.


The reason for this is simple. Grass roots take up nitrogen in the nitrate and ammonium forms. Turfgrass soils have relatively low concentrations of nitrogen, compared to the amount the grass will use. This chart shows the soil inorganic nitrogen (N in the ammonium and nitrate forms) from the Global Soil Survey samples as of August 2014, with each dot representing a single soil producing good performing turf. The red line is the median of those data (7.85 ppm) and the green line is the amount of N there would need to be in the soil to supply an annual rate of 20 g N m-2 (4 lbs N/1000 ft2).

AvailN2The soils producing turf have much less N in them, at any one time, than the grass will use over the upcoming months. Using the 6.7 conversion factor (explained here and here) for 1 g of an element applied to the surface, converted to ppm in the top 10 cm of the soil, there would have to be 134 ppm (20 * 6.7) of nitrogen in the soil to supply the amount the grass would use. That much N would be toxic, and that much N could cause uncontrolled growth if it didn't kill the grass -- that is not the way turf gets fertilized.

Because the amount of N in the soil is so much less than the amount the grass will use, soil tests for nitrogen are not useful as a predictor of fertilizer nitrogen.

Elements for which a soil test can predict fertilizer requirements will have levels of the element in the soil, compared to the amount the grass will use, looking completely different than shown above for nitrogen. Take a look at the same soils (data here), but this time with the Mehlich 3 K (potassium) plotted.

M3kThe green line (67 ppm) shows the estimated amount of K that the grass would use over the time that 20 g N m-2 were supplied. And the red line (70 ppm) shows the median Mehlich 3 K of the Global Soil Survey samples. The green line is the amount the grass may use, and all the black dots to the left of that will require fertilizer K. But unlike the chart for N, there are also some soils with K well to the right of the green line. In those soils, the amount of K in the soil is more than the amount the grass will use, and fertilizer K would not be required.

Because the distribution of K in soils includes levels of K that are both less than the grass will use, and more than the grass can use, one can use soil tests to determine K fertilizer recommendations.

For more about this, see:

A course like no other

The distinctive crest of the Club

I love hill stations. And the best hill stations all have golf courses. One of my favorites is Kodaikanal Golf Club (founded 1895). At an elevation of 2,100 m in the Palni Hills, and just 10° north of the equator, the clubhouse sits at the edge of a cliff, high above the plains.

Kodaikanal is 2,100 m above sea level and receives the most rainfall in southern Tamil Nadu

One of the great attractions of Kodaikanal (Kodai) is the temperate weather. This was my third visit. Each time I've taken the winding road up the mountain, I've watched the roadside grasses change with each kilometer. One sees the tropical grasses of the plains on the lower reaches of the mountains, with kikuyugrass (Pennistetum clandestinum) starting to appear as one gets closer to Kodai.

The uphill approach to the wide-open first

Ecologically, the golf club sits on a sky island. That is, it is at such an elevation, and surrounded on all sides by lowlands of a completely different environment, so one finds many endemic species here – along with introduced plants such as kikuyugrass.

Memani2Club Secretary G.S. Mani (pictured with me at right) takes special care to employ organic practices on this property.

I've been impressed with the fine conditions produced at this hill station course with a minimum of inputs, no pesticides,and only the smallest amounts of organic fertilizer. There is a real focus on improving the environment by providing wildlife habitat, removing invasive Acacia tress, planting of native species, and developing natural wetlands.

You may have noticed the fence and gate to enter to course, and on the approach to the first, there was a net around the green.

At the fourth, one can see the net that encircles the green – and the fine turf around the green.


Nets are placed around the greens every night to keep Indian gaur from walking and grazing on the green surfaces

Every night, Indian gaur come out of the forest and onto the course, starting from the 16th hole. This is the world's largest species of wild cattle, larger than the American bison, and the nets around the greens help to keep the gaur off the carefully maintained putting surfaces.

There are a lot more wildlife here than Indian gaur. Especially around the clubhouse, practice green, first tee, and 9th and 18th greens, one finds troops of bonnet macaques. This one is running across the kikuyugrass on the first tee.

In the fairways one finds kikuyugrass and common carpetgrass (Axonopus affinis) and many other species that are managed to produce a good playing surface.

On the greens, which are rolled multiple times each week to improve the smoothness, the primary species is blue couch (Digitaria didactyla), with some patches of invading kikuyugrass.

Clouds blowing in just before sunset at Kodaikanal Golf Club

Another great hill station is Ootacamund (Ooty), about 6 or 7 hours drive, on a separate Sky Island. One finds imported gorse on the golf course at Ooty, but I don't think there is any gorse at Kodai.

If you like reading about hill station golf courses, you may be intrigued with the fairway maintenance at the Ootacamund Gymkhana Club. That Club was founded in 1896, but no mechanical mowers have been used on the fairways. Photos and videos here of the fairway mowing at Ooty.

Kodai has more conventional fairway mowing, with a farm tractor pulling a well-maintained 3-gang reel mower. But with native grasses, cold mountain temperatures, no fairway irrigation, and no chemical fertilizers, there isn't a lot of mowing to do.

For photos and information about this fascinating place, this video from the 2012 IGU greenkeeping programme shows more.

Everyone knows zoysia grows slower than bermuda, except when ...

... it doesn't. In fact, there is one variety of manilagrass (Zoysia matrella) that consistently grows faster than bermudagrass in Southeast Asia. I've had occasion to study and measure this grass, and there is no doubt that it grows faster than bermuda here.

Manilagrass fairway on the Player Course at Orchard Golf and CC in the Philippines.

Some recent measurements have provided a bit more information. The grass I refer to is nuannoi, the manilagrass variety that is grown on nurseries in Thailand, that I've seen growing as far east as the Philippines, south to Singapore and Bali, and west to Dhaka. 

Many golf courses in Thailand were planted to bermudagrass when they were constructed in the 1990s and through a natural conversion process, the nuannoi has taken over. Courses such as Windmill, Green Valley, Thana City, and Phoenix Gold have all had this happen.

Banyan GC in Hua Hin, Thailand was planted to this grass at the time of construction.

I've measured how fast this grass spreads, both when it is invading bermudagrass, and when it is establishing on bare ground without competition from other grasses. Here are four separate measurements.

1. At the ATC research facility

Different species and varieties of warm-season grass at the ATC research facility in 2008.

More than 50 varieties of grass from various species were grown at the ATC research facility near Bangkok from 2006 until 2009. One of the interesting observations was just how quickly nuannoi manilagrass grew into Tifway 419 bermudagrass. Remember, people keep telling me that bermuda grows faster, and zoysia grows slower, but as you can see here, the invasion was only happening in one direction. Which grass is growing faster?

The yellow pen marks the farthest extent of manilagrass invasion into a plot of bermudagrass.

From the plot border, to the farthest point of invasion, was 2 meters at this point, and the grass had been planted for 2 years. This is a rate of 1 meter per year, or 8 cm per month.

2. In Samui

The Santiburi Samui CC opened at the end of 2003. It was planted to seashore paspalum, except for the Tifeagle greens.

The 2nd shot at Santiburi Samui in January 2004, when the fairways were still seashore paspalum.

Most of the seashore paspalum on the fairways and roughs died during a drought in 2005. Where the paspalum died, bermudagrass took its place. I first noticed a few small patch of nuannoi on fairways at Santiburi Samui in January 2007. Since then, the nuannoi has continued to expand into the bermuda, with the largest patches now having an area of about 140 m2.

Large patches of nuannoi on the Santiburi Samui fairways in May 2014.

Assuming that the size was one small plant in January 2007, and the patch of manilagrass is now 140 m2 in size, gives an expansion rate of 7 cm per month. 

Based on the measurements at the ATC research facility and at Samui, the rate of expansion into established bermudagrass was 7 and 8 cm per month, respectively. This expansion rate is useful for doing planned fairway conversions, both to know how long it will take for the nuannoi to take over, and to calculate an appropriate spacing for planting.

3. In a greenhouse experiment

I've shared some results from a greenhouse experiment conducted last year in Thailand, in which nuannoi manilagrass, Tifway 419 bermudagrass, and Salam seashore paspalum were established from stolons in a sand rootzone and the growth and the nutrient uptake were measured. After the grass was already grown in, during the duration of the fertilizer and clipping yield experiment, the nuannoi manilagrass had 52% more clipping yield than did the Tifway 419 bermudagrass.

But before that, it grew in faster from stolons also.

42 days
Nuannoi manilagrass 42 days after planting by placing 5 stolons in the pot.
Nuannoi manilagrass 48 days after planting by 5 stolons in each pot.

The manilagrass had grown in after 42 days (6 weeks). The planting rate of the stolons was 144 g/m2

4. At a sod farm

I've explained the process of manilagrass production on sod farms near Bangkok in this video, where the grass goes from planting to harvest in about 6 weeks.

Nutrient requirements and nutrient availability

This morning at the Idaho GCSA fall meeting, I talked about a modern method for estimating turf nutrient requirements. There was some excellent discussion as we went through the background and examples of this method. 

I explained how one can answer the question "Is this element required as fertilizer?" by identifying how much of an element the grass will use, how much of the element must be kept in the soil, and how much of the element is actually in the soil. These three numbers are the amount harvested, the MLSN guideline, and the soil test amount. 

There were questions about how to account for nutrients that aren't available. Or nutrients that are less available. Or if soil conditions could cause nutrients to be required as fertilizer even though it would appear that they are not required. This relative availability is something that is already accounted for, because of the way the soil tests work and how we can interpret them. I've written about this before, in the unambiguity of nutrient availability indices.

At the Park Grass experiment, one can observe the influence of fertilizer application on species composition of the meadow.

We also talked about the Park Grass experiment and how textbook recommendations for complete fertilizers and soil pH are not necessarily related to what we actually want or get with turfgrass conditions.

"After looking at my soil tests more in depth, ..."

In an e-mail conversation with Ryan Galles, we discussed calcium, soil tests, magnesium, and a bit more.

From Ryan, "I had recently listened to your YouTube video on calcium in the soil that you did with Larry at PACE Turf on the MLSN Guidelines. I have had some problems on greens and fairly high pH." He explained that he had added a calcium product into his fertilizer application this year, but was wondering, after watching the video, if he was "getting anything out of that product. I have attached my soil test from there where it seems my calcium levels are pretty high."

I replied:

At that pH [mid 7's] and at that amount of calcium in the soil [more than 1400 ppm], it seems the roots will have access to plenty of calcium. If there are problems on the greens, I don't think they would be associated with a lack of calcium availability or calcium supply to the roots. In fact the soil looks good as far as nutrient supply goes. So I suspect that any problems would be related to air content in the soil, water content in the soil -- more likely that it is physical conditions of the soil causing problems, rather than chemical.

Ryan wrote back:

I am also applying a carbon product to help with the uptake of those nutrients as we thought that was a major problem ... I'm on the Cascade Duplex 4:1 program and last year, replaced both head and tail irrigation nozzles, did 2 flushes late in the season, deep tine aerified to help break up any layers and get sand down deeper into the profile ... I also needle tined every other week. This problem only existed on 3 of my greens, but since changing the program this year have had no issues. We have had a year with abundant rain which always helps, but have had a lot better turf health and recovery along with color this year. Would that change your recommendation and cutting the Calcium product? 

With that additional information, I was pretty sure it wouldn't be a calcium issue, and I wrote the same to Ryan:

It sure sounds to me like the wetting agent program and the deep tine combined with the needle tining (and the weather, of course) would be the cause of the improvement, and it would be unrelated to nutrient availability in general or calcium supply specifically.

He has sent some additional information, and again I question whether it is the nutrient application that is causing the benefit, or other maintenance practices. 

From Ryan: 

I actually had Magnesium in the program this year and saw pretty good results even though there is an abundant amount in the soil. I used Iron last year for some color along with a pigment and would get good color for a few days, but this year I haven't seen greens look better utilizing the pigment and Mg together. The color would last the 2 weeks in between sprays. I'm guessing that a lot of those nutrients that were high in the soil test are being tied up in some way. Is there products out there or ways besides what I've tried to do to help make those nutrients more available for the turf. It would be nice to be able to save some costs and cut Mg out of the program, but with how nice of color it gave me all year, it's tough.

That sure sounds persuasive, but I'm still skeptical. I just haven't seen where adding magnesium makes the grass green. This is where check plots are especially useful. Especially since so many things have changed from last year to this year.

My response:

When using a pigment, one must be cautious in saying that magnesium is causing the effect. If you would do a check plot, where only pigment was applied, but not magnesium, or vice versa, then you could confirm that one or the other are causing the effect. 

I don't expect that magnesium is "tied up" -- I try to avoid that term because it is vague -- in your soil, so I would not be looking to do anything to make it more available [note that Mg is > 150 ppm, higher than both MLSN and conventional guidelines]. Now if you can apply magnesium only, without N, without Fe, without pigment, and get an effect, that would confirm that magnesium is providing a benefit. If you do that, please send photos. I would like to learn about that effect. I've heard people talk about it but I haven't seen it.

I hope I can learn more about magnesium here, or Ryan can either save some costs, or be more confident the Mg is required, through the use of a knockout trial. For more on how to do this, I like Dave Oatis's article, Sayin' It's So Doesn't Make it So, and the PACE Turf's guide to Testing Products and Practices.

Park Grass experiment video

Last week I was browsing the Sir John Bennet Lawes timeline and discovered this excellent video with plant ecologist Jonathan Storkey introducing the Park Grass Experiment.

The Park Grass experiment at Rothamsted was started in 1856 and has been continuously monitored ever since. That makes it the oldest experiment on permanent grassland in the world

The experiment was designed to investigate the effects of fertilizer application on hay yields. But what was quickly seen, within the first years of the experiment, was that application of the different fertilizers caused different species to grow. Lawes and Gilbert, in their first report on the experiment, remarked that:

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].

C.V. Piper wrote in 1924, after a visit to Rothamsted, that the Park Grass experiment results "carry lessons of high importance in the growing of golf turf." These lessons extend to any kind of turf, including lawns. I wrote about this with Frank Rossi in The Park Grass Experiment and the Fight Against Dogma. The fertilizers that you apply will influence the species that grow, and the Park Grass experiment is the archetype of this effect.

The types and rates of fertilizer and lime applied to the Park Grass experiment result in dramatic differences in species composition and plot appearance


Helicopter spraying

Pine wilt can kill infected trees within a few weeks. The pine wood nematode does the damage, but it is the pine sawyer beetle that spreads the deadly nematode.

Thus, disease measures for pine wilt involve control of the pine sawyer beetle. I learned about this today at Keya Golf Club in Fukuoka. There are approximately 25,000 pine trees at Keya, and helicopter application of insecticide can be completed on all these trees within one hour. 400 L of spray solution are added to the tank, the helicopter sprays that out, and then the process is repeated 3 more times. In total, the helicopter will make 4 runs, each time with 400 L of spray solution.

After observing the spraying from the ground, I got to take a ride in the helicopter and enjoyed a fine view of this classic golf course.