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April 2013

Video Describing Manilagrass Production at Thailand

This video shows how manilagrass (Zoysia matrella) is planted, grown, and harvested on Thailand's sod farms. Manilagrass is used throughout East and Southeast Asia on lawns, parks, golf courses, sports fields, roadsides, and cemeteries. What is especially remarkable about this method of production is the time it takes from planting to harvest. During the summer when the temperatures are at a maximum and the grass can grow quickly, harvestable manilagrass sod is ready 30 days after planting. During winter, when the temperatures are cooler, it takes about 40 days from planting to harvest.

I spoke on this topic at a recent meeting of the Midsouth Turfgrass Council in Memphis. 

Turfgrass Notes From Korea


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.

Sky72_oceanThat 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.

Sunwoon_scorecardI 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. 

GCSAA and Turfgrass Education

I recently visited the Golf Course Superintendents Association of America (GCSAA) headquarters in Lawrence, Kansas. I've been a GCSAA member for 19 years, and to have the chance to visit the association office and meet with their staff about a range of topics, especially turfgrass education, was a highlight of my trip to the United States.

GCSAA_paspalum_woods_webcastFor GCSAA members in Asia, the live webcasts with the associated library of recorded, on-demand webcasts are an immediately useful resource, provided as a free member benefit through support from Syngenta. On topics ranging from algae management on putting greens to bunker sand selection to ultradwarf bermudagrass greens, these webcasts are a valuable learning resource. 

I recently taught a webcast about seashore paspalum, and that webcast was recorded and is now available on-demand.

GCSAA have also delivered their Turf Science Academy at the Asia Golf Show and offer a range of self study and in-person educational programs. The highlight of course is the annual Golf Industry Show with its associated GCSAA Education Conference where hundreds of educational seminars are delivered to thousands of conference delegates.

Gcm_201207-2The association's monthly magazine (GCM) includes sections on topics sure to be of interest to golf course superintendents the world over. Last year, there was even an article about me and the work I do published in GCM and in its sister publication, GCM China.

There are extensive member benefits related to education, networking, and professional development, and Class A members even receive complimentary admission to The Masters Tournament. If you are interested in turfgrass management, education, and career development, but are not a member of GCSAA, you should investigate the membership benefits and consider how membership in GCSAA may help your career.

Turfgrass Management on a Different Scale


Last week I visited three sod farms near Memphis with Dr. Jim Brosnan from the University of Tennessee, where I am an adjunct professor in the Department of Plant Sciences. We saw grass production on a different scale to what I am used to seeing on golf courses and sports fields. The mowers are a lot bigger, and so are the sod cutters and all the other equipment used to plant, maintain, and harvest these huge fields of turf.


The grasses grown on these farms were different varieties of bermudagrass (Cynodon), japanese lawngrass (Zoysia japonica), manilagrass (Zoysia matrella), and tall fescue (Festuca arundinacea).

Winstead_turfI got to meet Bobby Winstead of Winstead Turf Farms, current president of Turfgrass Producers International (TPI). His farm is growing some of the popular new varieties such as Celebration and Discovery bermudagrasses and Palisades and Royal zoysiagrasses. 

We also went to Battle Sod Farm in the Mississippi Delta and McCurdy Sod Farms in Dyer, Tennessee. We learned about irrigation and drainage of the huge sod fields, which are often watered by center pivot irrigation. We saw different types of verticutters and sprigging and plugging machines, all of which allow grass to be planted and grown and harvested at a scale I had never seen before.

Herbicide_manualDr. Brosnan and I spoke at the monthly meeting of the Midsouth Turfgrass Council, where he introduced a new mobile weed manual and I explained how manilagrass sod is produced near Bangkok. In the United States, turfgrass production in general is very much mechanized, and the growth of manilagrass specifically is slow because of the temperate climate, with it taking more than a year to get a harvestable crop. At Thailand, the situation is almost completely reversed. Turfgrass production in general is almost entirely done manually, and manilagrass sod can be produced in five or six weeks, because it grows so well in the tropical climate.

I made this video a few years ago showing the techniques used in Thailand, and I will be putting together an updated version soon. Whether it is the large scale sod production in the United States or the small scale production in Thailand, it is fascinating to study about the techniques used to produce good turf.

Waterfall Chart of Putting Green Calcium Levels

Waterfall chart of potassium (K) on a golf course putting green shows why K is often required as fertilizer; the grass uses enough K in one year to drop the soil level below the MLSN guideline
A waterfall chart can be used to represent nutrient availability and use in turfgrass. This has been explained in case studies of a desirable element that is often added as fertilizer, potassium, and in the case of a less desirable element in turfgrass soils, sodium.

Potassium is often required as fertilizer because the grass uses more potassium than is available. The situation for calcium is quite different. The amount of calcium available in the soil is almost always much more than the grass requires.

This waterfall chart for calcium takes a look at the calcium in the soil and shows the various additions and subtractions of calcium over the course of a year.

Here is an explanation of these data.

  1. A blue horizontal line is drawn at 360 ppm. That is the MLSN guideline for calcium, meaning we want to keep soil calcium at or above 360 ppm, and when we do that, we have a high level of confidence that turfgrass will be supplied with ample calcium.
  2. The initial soil test level of 519 ppm is a typical level for sand rootzones. This is based on the median value of 100 soil samples taken from sand rootzones in five countries of Southeast Asia.
  3. Annual plant uptake is expected to decrease the amount of calcium in the soil by 27 ppm. This is based on an estimated annual harvest of 900 grams dry matter per square meter, with an average leaf tissue calcium content of 0.45%. This is typical of bermudagrass turf with a twelve month growing season. Use of calcium by cool-season grasses in a temperate climate would be about half of the amount shown here.
  4. No calcium is applied as fertilizer because it is not necessary. The amount in the soil is much higher than the MLSN guideline.
  5. I estimate an addition of 80 ppm calcium to the soil through irrigation water. This is based on an average calcium concentration in the irrigation water of 20 ppm, and an annual irrigation amount of 600 L/m2. This is a conservative estimate of irrigation application at Bangkok based on 150 days of irrigation at 4 mm per day. Note that the amount added by the irrigation water in this conservative case is three times the amount of calcium actually used by the grass.
  6. I estimate a leaching loss of 67 ppm. Normally calcium won't leach. But in this case it absolutely has to. Why? Because the soil cation exchange capacity (CEC) does not change. The exchange sites in the soil already have cations reversibly adsorbed to them at the time the irrigation water is applied. So some of the calcium added through irrigation must leach. There is no place for it to remain in the soil.
  7. Taking the initial amount of 519 ppm in the soil, subtracting the amounts used by the grass and lost by leaching, and accounting for the amount of calcium added in the irrigation water, we are left with 505 ppm calcium in the soil after one year. This is still well above the MLSN guideline for calcium and this demonstrates why none is required as fertilizer. 

For more information about calcium for turfgrass, see:

Nutrient profile: Calcium by Doug Soldat

How much calcium does turfgrass require?

Calcium deficiency in turfgrass, an imaginary problem?

Supplemental calcium applications to creeping bentgrass established on calcareous sand by St. John et al.

Turfgrass Mystery at the sod farm


I recently visited a sod farm in Tennessee and saw these sinkholes in a field of tall fescue (Festuca arundinacea). After the sod cutter went across the field and the individual pieces of sod were lifted, it became apparent that there was some tall fescue growing below grade.

This machine, shown here harvesting a field of hybrid bermudagrass (Cynodon), was used to cut the field of tall fescue.

I asked, "Can you identify what has caused this phenomenon?" There were many responses before the correct answer was given.

Some were close to the answer -- guesses of elephant tracks, water buffalo or horse footprints, groundhog holes, bird scrapings, bear footprints, misaligned aerification holes, fox damage, hail marks, repair plug removal, holes created by worms or insects, or perhaps rock removal from the field. The correct answer was that a cow or cows escaped into this field just after planting, pressing the tall fescue seed down and it remained there, growing in the footprints, until harvesting when those below-grade footprints appeared. Correct answer from Jason Haines below:

My advice is to keep large animals off of sod production fields, although the cows on this manilagrass (Zoysia matrella) sod farm in northern Vietnam, shown below, didn't cause any problems once the turf was established.


The Unambiguity of Nutrient Availability Indices

I've been asked a question about nutrient elements being "locked up" in the soil and if I could explain that. This question is in some way related to these posts about soil testing and nutrient requirements:

IndexIn those posts, I have not used the terms "locked up" or "tied up" to refer to nutrients in the soil that are unavailable for plant uptake. Those terms should not be used by professional turfgrass managers because they are ambiguous and do not give the mechanism by which the nutrients are supposedly unavailable.

If we would say that some of the phosphorus (P) applied as fertilizer becomes "locked up" in the soil, what does that really mean? Does it mean the P will be forever unavailable for plant uptake? Does it mean the P is temporarily unavailable? Does it mean that all the soil P is at risk of being unavailable? Should we use a liquid fertilizer instead, to avoid this ambiguous "lock up" in the soil? And what about calcium (Ca) in a high pH soil, is it "locked up" in the form of calcium carbonate? The questions go on and on, but cannot be answered clearly because of vague terminology. It is often the case that this ambiguous terminology goes together with dubious chemical assumptions.

We avoid these problems by using nutrient availability indices, of which the MLSN guidelines are an example. A nutrient availability index does not try to say that a certain pool of measured nutrient are all of that element available. It is simply a number that, if it has been carefully calibrated with turfgrass response or turfgrass performance, can be used to determine the probability of a plant response to additional applications of that nutrient. 

Pace_mlsnIn the soil, there are various forms (pools) of the nutrient elements. With potassium (K) for example, there will be some in soil solution, some on cation exchange sites, some in what is termed non-exchangeable forms, some in the soil particles (structural K), and some, perhaps, in undissolved or unreleased fertilizer granules, and a small amount in soil organic matter. But an availability index for K does not need or attempt to assess all of this. In the case of the Mehlich 3 extraction for K, we would be extracting from the soil almost all of the soluble and exchangeable K and a small portion of the non-exchangeable K and none of the structural K. But that index is useful, because after many experiments and calibration and study, we are confident that a value of 37 ppm K is sufficient for excellent turfgrass performance. 

If the index is less than 37 ppm, we would expect a positive response to added K. If the index is above 37 ppm, we do not expect a response to added K. Availability indices such as the MLSN guidelines are unambiguous and already incorporate the "locked up" nutrients. Not all nutrients in the soil are available for plant uptake. But they don't have to be. We just need to know if there are enough, or not enough. The MLSN guidelines provide an unambiguous answer.

How Much Potassium Does Grass Require?

In last week's TurfChat, in which we discussed the relationship between soil nutrient levels and weeds, I mentioned that recommendations for soil potassium (K) tend to be unreasonably high. We can see that particular section of the discussion beginning at the 31:55 time of the TurfChat video:


The most accurate, and consequently, the most useful, guidelines for interpreting soil nutrient levels for turfgrass are the minimum level for sustainable nutrition (MLSN) guidelines. These guidelines have been specifically developed for turfgrass with special consideration of the sandy soils that are commonly used for high traffic turfgrass areas.

Pace_mlsnThe MLSN guideline for K is 35 ppm.

I mentioned in the video that conventional guidelines are much higher, ranging typically from the conventional PACE Turf guideline of 110 ppm to the Penn State University target of at least 180 ppm. But there is no reason for soil K to be so high, nor can we expect most turfgrass soils to hold that much K.

When we look at the results of relevant research papers, we see that the recommendations developed after the completion of carefully controlled experiments give guideline levels very close to the MLSN guideline. Here are just a selection of typical results.

Ebdon et al., 2013: less than 50 ppm, Morgan extraction, "there were no observed changes in shoot and root growth in response to K fertilization even at low soil test K levels"

Paul, 1981: 20 ppm, ammonium acetate extraction, "beyond 20 ppm, there is no response to K fertilization"

Sartain, 2002, 30 ppm, Mehlich 1 extraction, "the critical Mehlich-1 extractable level of soil K appeared to be near 30 ppm"

Woods et al., 2006, less than 50 ppm, Mehlich 3, Morgan, and ammonium acetate extractions, "the current target ranges of extractable K in sand rootzones promote K fertilizer application that may be detrimental to turfgrass performance. Recommended levels of soil K should be reevaluated to avoid gratuitous use of K fertilizers"

The MLSN guidelines have done just that, and the methodology used to develop the MLSN guidelines results in a recommendation in line with those developed through controlled field research.

There are a number of implications resulting from using outdated and inaccurate K guidelines. It is obviously a waste of money to apply unnecessary potassium. There is wasted thought in trying to solve an imaginary problem. Application of K will reduce, unnaturally, and possibly to the detriment of plant health, the amount of calcium and magnesium in the grass. In some situations, it is expected that addition of K will increase the number of weed species that can grow. And unnecessary applications of K may cause other unexpected problems, such as increased disease.