Then the questions came up, why remove the snow, was it worth it, and was any lasting damage done by that process? I asked Jim Prusa for the answers, and he was kind enough to explain why. Here's Jim:
Growing up in the golf course business in Northern Ohio I was exposed to all the mythological lore about how bad it was to allow any traffic on a golf course in winter. My father, a superintendent, ripped me when he caught me playing golf in the snow using orange golf balls in the early 1960s — he was worried that members would want to do the same. So, I was convinced at an early age that any traffic on a golf course in cold winter regions was going to damage a golf course. If you search old articles you’ll find many ‘horror stories” with scary photos of winter damage from winter traffic on golf courses. Then I experienced winters in Japan and Korea.
In both Japan and Korea I’ve managed scores of golf courses where clearing off the snow and playing golf was the norm — especially in Korea! What I have found is 100% contrary to the North America scary mythology about damaging the golf course. Frankly, I have never seen 1 spec of damage to golf course in Japan or Korea caused by winter play. None.
I’ve begun to think that the scare mongering of many superintendents about damaging a golf course simply from traffic in winter is an effort to not have to do much in winter!
No damage. None. Use common sense and avoid big, wide heavy snowblowers — it is why we are developing our own lightweight, ‘gang’ snow blower systems. On greens use covers. Clear the snow from covers and then you can pull the covers off during the day (like they do on baseball sports fields) and recover at night.
We run a business and that means we want customers and gain revenues that far offset the costs. PLAY GOLF!
He sent along these photos of cover removal.
And then happy golfers enjoying the course.
That's been my experience in Japan as well. I thought winter play would damage the turf. But any damage that happened was temporary, disappearing by early spring, and being more than offset by the revenue. One can lose a lot of money with frost delays when there are customers wanting to pay to play golf. For more about this, see:
One of the questions during the presentation involved nutrient availability, specifically of P and K. To paraphrase, the question was "How can one know that the P and K measured by the soil test, and compared to the MLSN guideline, are available to the grass?"
One can know the availability by doing a soil test because that is what a soil test is. A soil test is measuring the availability index of an element. When there is a lower amount of an element, there is less of it available to the grass, and when there is a higher amount of an element, there is more of it available. The MLSN guidelines are set at a level that we are confident is more than enough availability to produce good turfgrass.
It is too cold in winter for any type of grass to grow, and during the spring, summer, and autumn, C3 species will grow more than C4 species. Of course, C4 species use less water than C3 species, tend to be more salt tolerant, and in this type of climate, will require less mowing due to the shorter growing season.
Playing golf on a Zoysia japonica fairway near Seoul, March
Zoysia japonica is in common use as a fairway and rough turf around Seoul, more so than it is in Beijing.
Bentgrass greens and Zoysia japonica through the green near Seoul, March
Based on the similar temperatures between Seoul and Beijing, Zoysia japonica would certainly perform well in the summer in Beijing. But with colder winters in Beijing than in Seoul, one would need to be more concerned about potential winterkill. It would seem that Beijing winters would be almost too cold for Zoysia japonica, based on the temperatures at which this species was killed in this experiment by Patton and Reicher.
I was in Korea a couple weeks ago for this seminar on putting green maintenance. That seminar lasted just an hour, and after lunch I spoke for a few hours with superintendents and course maintenance staff from the Golfzon County group.
The afternoon session was informal, and the questions were universally applicable. Here's what we discussed, with links to additional reading on these topics:
optimum mowing heights for creeping bentgrass on busy golf courses, when busy means more than 100,000 rounds for 18 holes; I don't know the answer to this one, but I suggested something in the range of 4 to 4.5 mm.
I was in Korea this week to speak at an event organized by Golf Seminar magazine for golf course superintendents, CEOs, and general managers. I spoke about 10 numbers for putting green maintenance.
At almost every golf course, the mowing height is known. Surprisingly, some of these other important numbers are not.
Although one doesn't need to know all these numbers, I suggested that adding more of these numbers to one's vocabulary will lead to improved putting green performance. This is a summary of the 10 numbers I talked about in this presentation.
1. mowing height
The mowing height of putting greens is almost always known on a daily basis. Depending on the grass type, time of year, and type of putting surface, the mowing height will usually be in the range of 2.5 to 5.0 mm.
2. stimpmeter reading
It is important to know the green speed, which is measured as the stimpmeter reading. I shared data from the hundreds of measurements I've made of green speed in Asia. For 328 measurements on creeping bentgrass greens, most have a stimpmeter reading between 7.5 and 10.5 feet.
The easiest way to improve ball roll, by increasing the green speed and improving the smoothness of the green, is by rolling. I shared data shown above showing the increase of 2 feet in green speed on a course in Japan when the green was rolled.
3. soil moisture
One should know the soil moisture content. This allows one to keep the soil air as high as possible and to minimize the amount of water used while avoiding drought stress.
4. soil air
One should also know the soil air content. We can consider the soil's solid matter to be a fixed amount, and the pore space to be a fixed amount. Once we know the total pore space (measure at a lab, or just estimate it at 50%), and when we know the soil water content, we will know how much air is in the soil. I showed the chart of tine spacing and tine diameter as a way to estimate how much of the putting green surface area will be removed by coring. If one is removing cores and filling the holes with sand, this can be a good technique in the management of soil air.
5. surface hardness
I also talked about surface hardness. The way the ball bounces on a green is important too. There are various meters available for measuring surface hardness, and I showed 4 of them here: the Precision USA firmness meter, the Clegg impact soil tester, the Tru-Firm, and the Yamanaka tester. Although there can be a lot of variability between soil moisture and surface hardness, sometimes – especially when the grass type and soil type are the same – there can be a strong relationship between the two measurements.
The data above are from a course with seashore paspalum on fairways, approaches, and greens, and with a sandcapped surface on all those areas. A Clegg reading of more than 87 is indicative of a relatively firm surface, and a reading of less than 87 is indicative of a relatively soft surface. In most cases, the surface hardness decreases (becomes softer) when the soil water content increases.
6. nitrogen (N) rate
Nitrogen (N) controls the growth rate. It is important to match the N supply to the desired growth rate of the grass. Too little N and too much N can both cause problems. For creeping bentgrass at Seoul, the annual N rate is expected to be from 15 to 40 g N m-2, depending on the desired conditions (and especially on how busy the course is). Some courses do well over 100,000 rounds of golf per year, so a relatively high growth rate is required to recover from traffic damage.
7. potassium (K) rate
Potassium (K) is the second most abundant mineral element in creeping bentgrass leaves, after nitrogen. Healthy bentgrass will use about twice as much nitrogen as K. Above we can see grass that is sufficient (far left) in K and then gradually moves through to severe deficiency at right, when no K is supplied. The best way to identify the K requirement involves soil testing; one can also estimate K requirement as simply being 50% of the N requirement. That is, if one applies 20 grams of N, the grass will be expected to use 10 grams of K.
8. P rate
After N and K, the next mineral element in abundance is phosphorus (P). Adequate supply of P is important for many things, and this element is especially well known for its importance in the development of a healthy root system. Bentgrass leaves have about 8 times as much N as they do P; soil testing to determine P requirement is best, but a quick estimate of P requirements involves taking 12.5% of the N rate. That is, if the grass is supplied with 20 grams of N, it will be using about 2.5 grams of P.
9. salt content of irrigation water
Almost every golf course putting green is supplied with supplemental irrigation water during times when drought stress must be prevented. But the salt content of the irrigation water is not always known. The water above looks clean, but in the water is dissolved more than 640 ppm salt. For creeping bentgrass, that concentration of salt, applied to the grass, and allowed to accumulate in the soil, could cause problems. Salt can be managed by leaching, but first one needs to know how much salt is in the water.
10. Holing-out-test > 80%
What we really want to do is have a reliable green surface, one on which a ball hit at the right pace and on the right line will have a high probability of going in the hole. This can be measured with the R&A Holing Out Test.
I went to Korea this week to teach about turfgrass nutrient requirements and the new MLSN guidelines. I taught for 4 hours as part of the 2014 Sky72 Winter Seminar, explaining how these 5 principles can be used to ensure any turfgrass, anywhere in the world, maintained to any standard, can be supplied with just enough of each essential nutrient:
The elemental content of fertilized turfgrass leaves is relatively constant
The amount of nitrogen supplied to the grass controls growth and uptake of other nutrients
A temperature-based growth potential can predict how much nitrogen the grass will use
The grass cannot use more nitrogen than is applied as fertilizer
The MLSN (minimum levels for sustainable nutrition) guidelines ensure that soil nutrient levels remain high enough to produce excellent turf conditions
Sky72 is the host of multiple professional tournaments each year and it was great to spend some time at this facility. We had lunch at the amazing Dream Golf Range, a circular driving range with hundreds of hitting platforms. It was (perhaps still is?) the world's largest driving range. If you've flown into Incheon, Sky72 is the course (4 actually) right at the airport. You may have seen this video produced by the course staff:
In a presentation I called A Modern Method for Determining Turfgrass Nutrient Requirements, I explained how an estimate of nutrient use, combined with the MLSN guidelines, and with a measurement of the nutrient levels in the soil, allows a turfgrass manager to know exactly how much of each nutrient must be supplied.
We can be confident that good performing turf can be produced in soils with nutrient levels at or above the MLSN guidelines. To ensure the soil remains at or above the MLSN guideline, we can determine the fertilizer requirement for any element by subtracting the amount present in the soil from the amount at the MLSN guideline added to the estimated harvest of that element by the grass.
I was at Korea last week, where I visited six different golf clubs. Two were 18 hole facilities, one of which is under construction, one has 9 holes and is open 24 hours a day for half the year, two have 36 holes, and one has 72 holes.
That is Sky72 Golf Club, adjacent to Seoul's Incheon Airport, and as is typical of many courses in Korea, the course is lighted so that rounds can begin before sunrise and continue into the middle of the night. Two of the courses at Sky72 do well over 100,000 rounds per year, and that amount of traffic brings with it certain challenges.
There is of course the challenge of just getting the maintenance work done, but also the wear from all the traffic is severe. This is especially a challenge when zoysiagrass (Zoysia japonica) is used, as it so often is because of the climate, because there are less than six months of growth for zoysia in Korea.
At the beginning of spring, we can see in the photo above that the creeping bentgrass green has excellent grass coverage, but the zoysiagrass surround at the back of the green has been worn completely away through traffic during the winter. And the traffic makes for some unusual maintenance on bentgrass greens, where the hole location is changed multiple times per day. This is usually about every 80 to 100 players, or up to six times a day, I was told, at courses such as Korea Public GC, which hosts about 110,000 annual rounds and is open 24 hours a day from May to November.
Greens of course require relatively high rates of nitrogen when they receive so much traffic. I've written extensively about the growth potential and how it can be used to predict nitrogen requirements. Calculating the cool-season growth potential (GP) for Seoul and estimating a monthly nitrogen use of 3.5 g N/m2 when the GP is 1, we get an estimated annual use of 18.1 g N/m2. But the busy courses are using, generally, 30 to 40 g N/m2, to achieve the necessary growth rates to recover from traffic of more than 100,000 golfers each year.
During construction, it is customary to plant zoysia using stolons embedded in biodegradable nets that are rolled out across the fairways. After just visiting sod farms in the United States and finding that zoysia sod was selling for just over $3/m2, it was interesting to note that these zoysia rolls in Korea are the same price, and the installed price, including a layer of sand topdressing, is close to $5/m2. Once the rainy season and the hot weather of summer comes, this grass will fill in rapidly, and the fairway pictured above will be ready for a soft opening by October.
I saw cool technology too. At Golfzon County Sunwoon, I played 18 holes, the caddy kept our score on a tablet computer and recorded the number of putts for each hole, and she also took photos of our group on the course. When I returned to the clubhouse, I simply entered my locker number into a kiosk, and the scorecard was printed with a photo from our round, the hole by hole score, and the number of putts I had taken. It looks like I've got some room for improvement!
But that could be checked too, for there were two holes on which a video camera recorded my tee shot, archiving the swings on a website for my viewing at a later date as a record of the round, and immediately viewable on the in-cart tablet computer through the on course WiFi network. There is really some cool technology involved with these systems, and it is something that made my round of golf more fun than it otherwise might have been.
We can look at temperature data for Seoul and Philadelphia and we find that the average temperatures throughout the year have almost complete overlap. So we might expect that with such similar temperatures on a month by month basis, the grasses used in those cities would be similar. But while the courses at Philadelphia are mostly cool-season grasses, what we find at Seoul are primarily courses planted to Zoysia japonica. Here is a dormant zoysia fairway near Seoul in early spring.
Why such a different choice of grass when the temperatures are the same? I suggest that it has to do with summer precipitation.
From June through September, Seoul has a higher monthly average rainfall than does Philadelphia, and during the two hottest months of the year, July and August, Seoul has more than three times the rainfall, on average, than does Philadelphia. This combination of high temperature with high precipitation can be deadly for cool season grasses.