Silica and Green Speed

This is something that has never made sense to me. Actually, it seems ridiculous. Zoysia greens are not renowned for being especially fast. But zoysia has especially high silica content in the leaves. Duble, writing about Zoysia: "The species vary from extremely fine textured to coarse textured types and the leaf blades are very stiff due to a high silica content."

So if silica does make greens faster, shouldn't zoysia greens be lightning fast?

I was reminded of it this week, so I checked Nikolai's fine book, The Superintendent's Guide to Controlling Putting Green Speed, on the topic. I'd heard that silica application is supposed to increase green speed by making the leaves more turgid. I looked up the topic in Nikolai. He mentioned one study by Trenholm et al. on seashore paspalum in which silica application led to "increased turgor pressure of the turfgrass leaves."

Then, Nikolai had this short statement:

"For this reason, it is assumed that silica might enhance green speed, but, unfortunately, no study has tested this notion ... Clearly, more data is needed on this subject."

The book came out ten years ago. Anyone have some data on this subject since then?

I've reviewed 540 stimpmeter readings I made in 2011. These greens were in Japan, Vietnam, USA, Philippines, India, and Thailand. The species are listed in the table below, along with the average green speed by grass species.

species # of measurements average speed (feet)
creeping bentgrass 249 8.7
bent-poa 18 9.9
bermuda 107 8.5
fine fescue 15 8.6
zoysia 42 7.8
seashore paspalum 90 8.2
Poa annua 19 9.9

This is nothing against zoysia greens. Zoysia greens can be quite good.

Above is the 18th at Wack Wack during the Philippine Open. Below is roll on a zoysia green at Keya Golf Club in Japan.

The roll can be excellent. But it takes a lot of work to get the conditions shown. Just a high silica content of the leaves, and a high turgidity of the leaves contributing to faster green speed? I don't get it.

Honda LPGA at Siam CC, Novotek, Seashore Paspalum, and the #STMIA15 Field Day

The 2015 Honda LPGA Thailand is underway at the Siam CC Old Course this week. Here's a look at the first round highlights.

The greens are Novotek bermudagrass, and the fairways are seashore paspalum. They look great. And the players are making lots of birdies and even eagles on these smooth greens.

At Siam CC, there are 3 courses on adjacent property. The Old Course, closest to Pattaya, down the valley to the Waterside Course, and up the other side of the valley to the 27 hole Plantation Course.

On March 10, the Waterside Course will host the Asian Turfgrass Field Day -- preview here. This is part of the Sustainable Turfgrass Management in Asia 2015 conference. Also, on March 12, conference delegates have the chance to play golf at either the Plantation (host venue for the 2015 Thailand Open) or the Waterside Course at a special conference delegate rate.

More about grasses on golf courses in Thailand: a Christmas Eve miscellany

Sunset_banyanGolf in Thailand at this time of year is really pleasant. I often use the words clement and salubrious, with additional modifiers, to express just how pleasant I find it.

Over the past 20 days in Bangkok, there has been no rain, and the temperature has ranged from 19 to 34°C.

I've written about the grasses one finds here, and I have also put together this photo gallery of the typical grasses. Most putting greens are hybrid bermudagrass, and after that comes manilagrass, and there are comparatively few courses with seashore paspalum greens.

Through the green, the percentage of courses with bermudagrass goes down, and the percentage with manilagrass and seashore paspalum comes up.

Turfgrass @ Thailand

At the Sustainable Turfgrass Management in Asia 2015 conference, we will be talking about these grasses, and we will have a pre-conference seminar in which we discuss the design and construction of golf courses in Southeast Asia.


It hasn't rained in Bangkok for 20 days, yet on the seashore paspalum fairways I played today, this was the result from multiple shots that landed in the fairway: debris (organic matter, or mud?) on the ball.

2014-12-24 13.50.15 2014-12-24 11.20.57 2014-12-24 11.38.52
I think the cause of this is related to the grass species. In Southeast Asia, when one does not keep the soil wet, seashore paspalum will eventually be overtaken by better-adapted species that thrive in drier soils. So seashore paspalum fairways must be kept really wet if the grass is to persist. One can topdress with large amounts of sand to minimize that problem, but that is really expensive.

A recent post on about seashore paspalum had some interesting comments from golf course superintendents and golfers and architects about this species. The consensus -- it requires a lot of inputs and can be very expensive to maintain.

I've got lots of ideas about grass selection and construction methods (especially sandcapping of fairways) and will be working on developing those for discussion at the upcoming conference. 

Of drought resistance, N:K ratios, experiments, and inferences

The evidence continues to accumulate. Adding more K in relation to N doesn't seem to do much. Rowland et al. wrote about their experiment that looked at drought resistance of warm-season putting green grasses grown in sand, treated with different rates of potassium.

They studied drought resistance of four cultivars:

  • bermudagrass, Tifeagle and Tifdwarf
  • seashore paspalum, SeaDwarf
  • zoysiagrass, PristineFlora

Here are some of the results from their research:

Increasing K in relation to N failed to increase drought resistance for the cultivars studied.

Applying K at ratios above 1N:1K did not increase drought tolerance and may have actually hindered it, as wilting increased (P < 0.10) on two rating dates when 1N:4K was compared to 1N:1K. This was likely due to saturated K levels within the leaf tissue and an increase in soil solution salts.

Our results indicate that increasing N/K ratios above 1N:1K is not beneficial, and in fact may impart a negative effect on drought resistance.

In a previous discussion of these results, Jon Wall had this suggestion:

That's a good idea. I have a few comments on those specific rates.

1. If I were doing a follow-up on this, I would try to minimize the number of treatments. The more treatments there are, the more time, space, and expense involved in doing the experiment. Bermudagrass leaves usually have from 3 to 4% nitrogen (N) and about 2% potassium (K). I conservatively estimate the ratio in the leaves of this species at 3:2, which would be 1:0.66. 

If the soil has a reasonable amount of K, then K added as fertilizer won't have an effect, because the grass will be able to obtain all the K it requires, even if the N:K ratio is 1:0. One could do the experiment in a rootzone with low K, and I would try to do it with just 2 or 3 treatments – 1:0.33 and 1:1 for sure, and maybe 1:0.66. By measuring what happens at the 1:0.33 and 1:1 treatment levels – bracketing the levels of K that the grass can use –  and what the magnitude of the effect is going from one level to the next, one could infer what would happen at intermediate levels of K supply.

2. On the topic of inferences, there is lots of data showing that supply of K in the amount the grass can use is the rate of K that optimizes a number of plant performance characteristics. These cited results are for bermudagrass in Florida.

Cisar et al. found a ratio of 10:1.25 sufficient even with high sodium application.

Snyder and Cisar saw reduced visual quality when the N:K ratio dropped below 2:1.

Snyder and Cisar reported this: "Severe K deficiencies were observed in the absence of K fertilization. However, increasing K fertilization beyond a K/N fertilization ratio of 0.5 to 1 had virtually no effect on turfgrass appearance, growth, on resistance to bermudagrass decline, or on root weight."

What inferences can one make from these experiments and from Rowland et al.? Adding more K than the grass can use doesn't do anything good. Adding less K than the grass can use, if the soil is also low in K, will cause problems.

3. Because the results are so consistent, I think the optimum N:K ratio is pretty predictable. It is in the range of 2:1 to 3:2, assuming the soil K is relatively low, say at less than 50 ppm by Mehlich 3. When the soil K is higher, the amount of K added can be reduced, because the soil will be able to supply some of the K used by the grass.

4. This would be a great test to do on a nursery area. Using the procedures described in PACE Turf's guide to testing products and practices, one could apply different N:K ratios. That is straightforward. And then one could withhold irrigation and wait for the grass to start wilting, and look at the grass treated with different N:K ratios to determine if there was any N:K effect on when the grass starts to wilt. That, basically, is drought resistance. 

Not entirely a surprise

At the Poipu Bay area of Kauai, most hotel lawns are seashore paspalum. This lawn at the Sheraton Kauai is a typical example.

Under the trees, though, closer to the beach, a different species grows. 

This is manilagrass (Zoysia matrella). It is growing under the trees and creeping onto the rocky beach.

In fact, it even grows right on the beach. The manilagrass is salt tolerant, drought tolerant, and has a finer leaf blade than the seashore paspalum. One might expect to see the seashore paspalum growing closer to the ocean, but in this case, it is the manilagrass that grows right at the water's edge.

For more about these grasses, see:

"The salesmen all suggest Calcium"

Amino_fert_9-6-5Jason Chennault and I had a conversation about interpreting soil tests. 

I had seen test results for a site and didn't think there were any problems with the soil. Jason wrote back with more information.

An example is the salesmen all suggest Calcium (and yes I know your thoughts about that :) ) but suggest applying foliar P, noting it won't be soil applied nor adding to the soil. They suggest that I'm high in S, my Ca and Mg ratios are concerning and on and on. Nothing that persuades me to do one thing or another exactly, just there's so many interpretations of the sample results.

There are certainly many interpretations of test results, but that doesn't mean all interpretations are correct. I think it makes sense to interpret soil tests in this way.

  1. Make the assumption that if there is enough of an element, then adding more of that element will have no effect.
  2. Don't worry about the specific function of each element. Rather, make sure that enough of each element is supplied to the grass.
  3. Then, find out how much is enough.
  4. This can be done by making sure that the amount of an element in the soil stays above the MLSN guideline
  5. Because the MLSN guidelines have been identified from soils that produce high quality turf, and have a safety margin built in to ensure they are not too low, have confidence that as long as nutrient levels remain above the MLSN guideline, the turf will be supplied with all of that nutrient that it needs. 

After going through that process of interpretation (full explanation and examples here), I like to remember this quote from Wayne Kussow: "How many more times do I have to say that applying nutrients to turfgrass growing on soil already well supplied with the nutrients is a waste of time and money?"

Turfgrass ecology, part 2: abandoned turf in Thailand

In the southern Tohoku region of Japan, ceasing maintenance of creeping bentgrass leads to grass death and almost complete invasion by weeds. Manilagrass (Zoysia matrella) stays alive for at least 18 months with no maintenance, and has minimal weed invasion. Japanese lawngrass (Zoysia japonica) also stays alive, but has more weed invasion than seen on manilagrass.

What happens with manilagrass and other grasses like seashore paspalum (Paspalum vaginatum) and hybrid bermudagrass (Cynodon dactylon x C. transvaalensis) when maintenance is stopped in the tropical conditions of Thailand? And do observations of what happens when there is no maintenance have some implication on what the maintenance requirements may be for those grasses? 

The Asian Turfgrass Center research facility north of Bangkok in 2008. The grass was maintained at this facility from 2006 until April 2009.

At the TT Tour in January 2008, we studied various grasses at the research facility. The grass immediately surrounding the paved area is manilagrass, and adjacent to the sala with the red tile roof is centipedegrass (Eremochloa ophiuroides).

Manilagrass at the edge of the potted grass nursery at the ATC research facility in January 2008.

In April 2009, irrigation was stopped at the research facility, and mowing was stopped from October 2009. So what happened to this manilagrass by November 2010, 19 months after the last irrigation, and 13 months after the last mowing? This is in Thailand, where the temperature is always warm, and the grass (and weeds) have the potential to grow all 12 months of the year. 

The next photo shows the same area as the previous photo, but at a different angle; the paved area is now at left (and covered by weeds); the manilagrass that people are standing on in the above photo is in the center of the photo below.

Manilagrass remains alive and free of weeds after 19 months with no irrigation and 13 months of no mowing. The centipidedegrass beside the sala has been overrun by weeds in the same time.

 How about bermudagrass and seashore paspalum?

Mowing was continued, but irrigation had been withheld for 5 months. Seashore paspalum is in the foreground, and bermudagrass is in the background.

The rainy season in this part of Thailand goes from late May until the end of October. The photo above was taken in mid-September 2009. Irrigation was stopped in April. Even though the grass was growing through the rainy season, the seashore paspalum in the foreground has almost all died without supplemental irrigation in only 5 months. The bermudagrass in the background remains alive, as does the surrounding manilagrass.

This next photo is taken from the same plot of mostly dead seashore paspalum, but turned to a different angle to show manilagrass in the background. The manilagrass, of course, remains alive with the natural rainfall and no supplemental irrigation.

After 5 months without supplemental irrigation, the seashore paspalum in the foreground is almost all dead. The manilagrass in the background remains alive.

Those photos showed the seashore paspalum after 5 months without irrigation. What happens after 19 months of no irrigation and 13 months with no mowing? In that case, the seashore paspalum has all died.

The plot of seashore paspalum 19 months after maintenance was stopped. It has now all disappeared and some weeds and other grasses are invading.

Seeing what happens when maintenance is withheld gives some indication of how much maintenance (irrigation, fertilizer, pesticides, mowing) are required when a species actually is maintained. Under the conditions of central Thailand, one can make some general observations based on this comparison of unmaintained grasses.

  • manilagrass seems to require only mowing to persist as a turfgrass and is the most resistant to weed invasion
  • seashore paspalum dies without supplemental irrigation
  • bermudagrass does not die without supplemental irrigation but will eventually be invaded by weeds if not maintained intensively

These observations of manilagrass are very similar to what was seen in the photos from Japan. Also, these observations of dying seashore paspalum are similar to what was seen in a controlled experiment in southern China. Xie et al. found that seashore paspalum turf under low maintenance was naturally replaced by manilagrass within 2 to 3 years.

Increasing potassium "may impart a negative effect on drought resistance"


Does adding more potassium improve drought resistance? This just-published paper by Rowland et al. takes an in-depth look at that important question.

They looked at bermudagrass (Tifeagle and Tifdwarf), seashore paspalum (SeaDwarf), and zoysia (PristineFlora) grown in a USGA sand rootzone. The amount of potassium applied to the grass ranged from 4.9 to 19.6 g m-2 30 d-1. Nitrogen was applied at 4.9 g m-2 30 d-1, so that created N:K application ratios of 1:1, 1:2, 1:3, and 1:4. Irrigation was applied at 25, 50, and 100% of daily ETo. Then they measured wilting, soil moisture, root length, turf quality, leaf chlorophyll, normalized difference vegetative index (NDVI), and thatch depth.

One might have expected potassium application, or increasing the amount of potassium applied in relation to nitrogen, to have some positive effect on at least some of these parameters. You might be surprised then, at what actually happened. Rowland et al. report that:

Applying K at ratios above 1N:1K did not increase drought tolerance and may have actually hindered it, as wilting increased (P < 0.10) on two rating dates when 1N:4K was compared to 1N:1K. This was likely due to saturated K levels within the leaf tissue and an increase in soil solution salts.

How about the soil volumetric water content (VWC)?

There were no differences in VWC among N/K ratios.

And that is what was observed in every parameter measured. Whether it was turfgrass quality, NDVI, root length, or thatch depth, adding more potassium didn't improve anything. They conclude:

Our results indicate that increasing N/K ratios above 1N:1K is not beneficial, and in fact may impart a negative effect on drought resistance.

These results show that when the grass is supplied with enough potassium, adding more does not provide any benefit. For more about this, see:

3 fine football fields

On the eve of the World Cup, I have three quick things to share about football/soccer. 

Kashima Soccer Stadium, March 2014

1. I've been to two matches at the Kashima Soccer Stadium (this was a venue for World Cup games in 2002) in the past year, one at the end of summer, and one at the beginning of spring. The grass is a mixture of 2 kentucky bluegrass (Poa pratensis) varieties and one hybrid bluegrass variety. In this part of Japan it would be typical to use warm-season grasses on sports fields – summer temperatures are similar to those in Atlanta – and on the surrounding golf courses and lawns, warm season grasses are grown. I've been impressed at just how good the turf is here. Almost all the stadiums in J.1 are bermudagrass, so this pitch at Kashima Stadium is exceptional in being cool-season grass, and exceptional in being maintained to such a high standard. 

2. In the Thai Premier League, one can find matches played on bermudagrass, zoysiagrass, and seashore paspalum. Muangthong United play at the SCG Stadium on the north side of Bangkok, and the pitch here is seashore paspalum.

Seashore paspalum at SCG Stadium in Bangkok, April 2014

To keep the ball moving quickly, water is added at halftime. 

Irrigation at halftime, SCG Stadium

This is the best pitch I've seen in Thailand.

3. If you haven't watched this feel-good story about the amazing Panyee FC in an amazing part of Thailand, take a couple minutes and watch it now. I bet you haven't seen football played like this.