Viridescent - the Asian Turfgrass Center blog

Understanding Data Use for Turf Management: presentation slides (with video) from Thailand

This week I spoke to a full room of turfgrass managers at Bangkok's Thana City Golf and Sport Club about an important topic: understanding data for use in turfgrass management. I've recorded this video of the presentation slides in which I discuss the two classes of data that can be collected – data about playing surface performance, or data about plant growth – and then I go into some detail about soil moisture and photosynthetically active radiation (PAR), with a brief mention of salinity and soil pH at the end.

There were many questions and an active discussion in this seminar and in fact lunch time arrived before I could speak about salinity and soil pH, so this video provides the narration of what I would have talked about had there been more time.

David Lau from Spectrum Technologies, pictured with me at right, gave an interesting presentation in which he talked about a broad range of meters and software that can be used to collect and analyze information for improving turfgrass performance. This is part of what PACE Turf call Precision Turfgrass Management (PTM), which is a systematic effort to provide optimum turf performance using minimum resources. As David mentioned, we cannot manage something if we do not measure it.

For more information about the data I discussed, you may be interested to read this report about putting green performance, including extensive sections and data on soil moisture and temperature, and this report about photosynthetic irradiance.

The Difference in Leaf Temperature Between Wilting and Transpiring Grass

Today was an especially hot day at Bangkok. I went out for lunch, and when I was driving home I noticed that the thermometer on my dashboard was indicating an outside temperature of 42°C. Upon arriving home, I checked the official temperature, found it to be 38°C, and I promptly went outside with my infrared thermometer to measure the surface temperature of concrete and of grass. See the above image at full size here.

These measurements were made at 14:00. The concrete measured 53.6°C, about 15°C above the air temperature. Manilagrass (Zoysia matrella) wilting in the sun had a similar temperature, 48.8°C, more than 10°C above the air temperature. Meanwhile, manilagrass and carpetgrass (Axonopus compressus) in the same lawn, in areas with adequate water so the grass could transpire, had leaf temperatures ranging from 1.8°C below to 1.2°C above the ambient air temperature.

As part of a putting green performance data research project, I've collected leaf temperature data from hundreds of greens across multiple grass species in many countries. As of today, I've measured the surface temperature 802 times. If you are interested in reading more, these data are summarized beginning on page 21 of this report. It has been my observation that in conditions of full sun, minimal wind, and adequate plant water status, meaning the grass leaves are not wilting, no matter how hight the ambient air temperature, the leaf temperature will generally be within 1°C or 2°C of the air temperature. Have you ever measured anything different?

For those more familiar with °F than °C:

38°C = 100.4°F

53.6°C = 128.5°F

Waterfall Chart of Putting Green Sodium Levels

I have decscribed how a waterfall chart can be used to show the nutrients that enter and leave a system, using potassium as an example. In that example, I did not show any input of potassium from irrigation water or rainfall, because I made the assumption that those inputs would be negligible. David Kuypers, the Golf Course & Grounds Superintendent at Cutten Fields in Guelph, Ontario, asked what would happen with sodium (Na) added through irrigation water:

@asianturfgrass Any need to account for an input through irrigation water? Average here is 110ppm for Na. Impact reflected in soil test?

— David Kuypers (@gcscuttenfields) March 19, 2013

That is an excellent question, and this chart for Na shows what may happen with that element. Let's look at a few components of this waterfall chart.

1. The horizontal blue line at 110 ppm marks the MLSN guideline for Na. Unlike the 35 ppm level for K, which is a minimum guideline, this 110 ppm maximum guideline for Na is related to increased chance of rapid blight disease at soil Na concentrations above 110 ppm.
2. I assume that we start with a Mehlich 3 extractable Na of 75 ppm. The annual plant uptake of Na is minimal for cool-season grass and I estimate it as being equivalent to a decrease in soil Na of 5 ppm. 
3. I assume no Na is added as fertilizer.
4. David said that his irrigation water has an average Na concentration of 110 ppm. That means for each liter of water, there are 110 mg of Na. If he adds 205 mm of irrigation water to the greens over the course of the season, that is equivalent to 205 L of water for each square meter. If we assume that the 22,550 mg of Na contained in those 205 L of irrigation water are distributed throughout the top 10 cm of the rootzone, and that the bulk density of the rootzone is 1.5 g/cm³, then that amount of Na will increase the Na in the system by 150 ppm.
5. With this depiction on the waterfall chart, we can see that the amount of Na expected to be added with this much irrigation is twice the amount of Na that was in the soil at the start of the year. And we can make some comparison of the magnitude of each input and loss of Na from the system.
6. However, sometimes there will be thunderstorms or other heavy rain events that will cause some leaching of that Na. Most of that Na will be remaining in soil solution; it won't be extensively held on cation exchange sites which would make it resistant to leaching. And if rain doesn't come, I assume that David will sometimes apply extra irrigation water to induce leaching of the Na. I assume that 130 ppm of the Na will be lost by leaching.
7. With these assumptions, that leaves us at the end of the year with 90 ppm of Na in the soil, still below the 110 ppm MLSN guideline. And if we would go through the fall, and through the winter, we would expect no irrigation water to be applied, and some leaching to occur, and by the start of the next irrigation season, the Na would be reduced even more. In an arid climate, the Na would be expected to increase and increase, but in a humid climate, one in which precipitation exceeds evapotranspiration, most of the applied Na is expected to leach.
8. We can see that if no leaching occurs, the addition of Na through irrigation will increase soil Na above the MLSN guideline of 110 ppm.

For more about maintaining soil Na below 110 ppm, see this document from PACE Turf.

Sand, Sodium, and Soil Structure

Sand rootzones are common the world over for golf course putting greens. Many athletic fields are also built with a sand rootzone, and in Asia, many of the tees, fairways, and even roughs are grown in a sand rootzone. Is sodium a problem for structure of these soils? The answer is a resounding NO. 

From the chapter Warm-season Turfgrass Fertilization by Snyder et al. in the Handbook of Turfgrass Management and Physiology, we learn that the "very sandy soils that often are used for golf greens and athletic fields have no structure and are largely unaffected by sodium."

Research presented at the 2012 Crop Science Society of America Annual Meeting by Obear et al. also showed that extremely high levels of sodium have no effect on the saturated hydraulic conductivity of sand rootzones. In this paper, Effect of Sodium On Saturated Hydraulic Conductivity of Sand-Based Putting Green Root Zones, sand, sand with various amendments, and a silty clay loam, were saturated with waters of varying sodium levels. The saturating solution with the highest amount of sodium had a sodium adsorption ratio (SAR) of 80, which is extremely high. 

But when the saturated hydraulic conductivity of the soils was measured, none of the sands, even those with the highest amounts of sodium, had a decrease in water movement through the profile. 

There are a few reasons to pay attention to sodium. In soils with appreciable levels of clay, soil structure can be negatively affected by sodium. If rapid blight is a possibility at one's property, then the soil sodium should be kept at less than 110 ppm. And one should be aware of the electrical conductivity (EC_w) of the irrigation water and of the soil (EC_e). Sodium can be a major contributor to that, and if the EC_e approaches the threshold level for a species, steps should be taken to manage the soil salinity.

But sodium and soil structure in sand rootzones? That is not something to be concerned about.

My View About Grass Selection on new Golf Course Management website

The R&A have put together a new website rich in information about golf course management. The site, appropriately, is titled Golf Course Management: information, resources, and tools.

In the My View section I've written about grass selection for greens and fairways in Asia. My view is that when it comes to putting greens, because they occupy such a small area of the course and no matter which grass is chosen the greens will always receive intensive maintenance, a high maintenance grass is often the right choice. And my view for fairway turf, because fairways occupy such a large area of the course, is that it is best to choose a grass that won't die. When the grass won't die, then turfgrass managers are able to modify the playing conditions to create almost any type of surface. In Southeast Asia, these grasses that don't die are manilagrass (Zoysia matrella) and broadleaf carpetgrass (Axonopus compressus).

The site is packed with information including My View pieces by other golf course specialists, case studies, including those of courses that have used just those grasses. Read about Thailand's award-winning Banyan Golf Club with its manilagrass fairways and the amazing East Course at Wack Wack Golf and Country Club in Manila. This course, with carpetgrass fairways, was just selected as the best course in the Philippines.

There is also the Course Tracker, a new tool to monitor, analyse, and report on your course, and the introduction of the Holing Out Test for assessing putting surface reliability. In the video below, I demonstrate the Holing Out Test on creeping bentgrass putting greens in Japan.

Soil and Water Testing for Turfgrass: valuable tool, or absurd pretense?

Glaring errors on soil and water test reports are a source of frustration and concern. Soil nutrient analyses (soil tests) and irrigation water analyses (water tests) can be a valuable tool, but sometimes they are more like a charade. Errors on these reports are more common than one might think, although I expect that a number of report templates will be changed after reading this.  

Here are the top 3 errors I've commonly found on soil and/or water reports. Surprisingly, one can find these errors on reports from multiple laboratories, from multiple companies.

1. The misspelling of phosphorus as phosphorous. Phosphorous is an adjective and is not the element P, which is spelled phosphorus. Phosphorous, in fact, means phosphorescent, glowing. How much can we trust the results if one of the major macronutrients is not spelled correctly? Might there be other errors in the report? 

2. Sodium adsorbtion ratio. Wrong. Sodium absorption ratio. Also wrong. Let's try sodium adsorption ratio. That's right. How is it that laboratories can misspell such an important irrigation water quality parameter? It is not like there is an option of how to spell this. It is either right or wrong. Sodium adsorption ratio (SAR) is one of the most important parameters to look at when evaluating water for irrigation suitability. Sending out reports and water quality guides with such errors makes one wonder about other possible errors in the report.

3. How about irrigation water tests that don't report SAR? That is not very useful at all. The two most important parameters on an irrigation water suitability test are the sodium adsorption ratio (SAR) and the electrical conductivity (EC). The total dissolved solids (TDS) are an analog of EC. If you get a water report without SAR, or without EC, you are not getting the data you need. 

Then, of course, there is the really big error, which I won't write about in detail here, but for turfgrass, the classification of soils as being high, optimal, or deficient in a particular element is usually quite far from correct. I don't know exactly what is correct, but the best approximations I know of are the Minimum Levels for Sustainable Nutrition (MLSN) guidelines. I've been working on these with Dr. Larry Stowell from PACE Turf over the past year, and this ongoing project aims to refine turfgrass nutritional guidelines. If you are really interested in this, you can read more about it here.

Turfgrass in Catalonia: 1

Occasionally I get to travel to places that have a tremendous variety of grasses. One of these is Hawaii – a wonderland of grasses. But at Hawaii it is a panoply of warm-season grasses. Recently I visited Catalonia, at the invitation of David Bataller, Golf Courses and Grounds Manager of the PGA Catalunya Resort. What I saw was really amazing! Almost every warm-season and cool-season turfgrass was growing in this region.

It is always interesting and a great learning experience to see so many types of grass. One thing that remains consistent about places where a lot of grasses, both cool- and warm-season species can grow, is this: these are among the most difficult places in the world to produce good year-round playing surfaces.

At this 36-hole facility, David manages primarily cool-season grasses, but there are also warm-season grasses – in fact, I counted ten different species of turfgrass, in total, being used on the property, plus lovegrass (Eragrostis) put to good use in many landscaping and out-of-play areas. In no particular order, they are:

• Lolium perenne (C₃)
• Zoysia japonica (C₄)
• Pennisetum clandestinum (C₄)
• Poa annua (C₃)
• Poa trivialis (C₃)
• Poa pratensis (C₃)
• Agrostis stolonifera (C₃)
• Cynodon dactylon (and Cynodon hybrids) (C₄)
• Paspalum vaginatum (C₄)
• Festuca arundinacea (C₃)

Why are there such a wide variety of grasses used for turf in Catalonia? If we look at a chart of growth potential through the year (Figure 1), it would seem that cool-season grasses would be a clear choice for this area. 

Figure 1. Temperature-based growth potential of C₃ and C₄ grasses based on climatological normals data for Girona, Spain.

The chart shows that the cool-season growth potential is higher than warm-season growth potential throughout the year. But what we find growing are both cool- and warm-season grasses. This is similar to a place like San Diego, California, where we can find seashore paspalum and bermudagrass and kikuyugrass growing alongside perennial ryegrass, Poa annua, and creeping bentgrass. 

The reason warm-season grasses perform well in this type of climate is because of water. Warm-season grasses have better water use efficiency than do cool-season grasses, and warm-season grasses generally have better salinity tolerance than do cool-season grasses. So in a climate where the evapotranspiration is higher than the precipitation, and where the irrigation water has some salt in it, warm-season grasses will compete well with and may even outperform cool-season grasses.

During the winter season, the warm-season grasses go dormant, as we can see with the Zoysia japonica on the bunker slope, but it is not cold enough for there to be any winterkill. 

There was even a local type of seashore paspalum (seedhead at right) that grows well in this area, and in fact some of the older golf courses near the sea in Catalonia have this native grass.

After the vist to PGA Catalunya Resort, my head was spinning. We had seen so many types of grasses, seen sunrises over the frost-covered courses, had discussed the soil and water salinity challenges, and tried to predict how certain grasses would grow at different times of the year. Maintaining fine turfgrass in a transitional climate, especially one without much precipitation, is really a challenge. 

Thai GCSA Meeting: Managing Organic Matter in Sand Rootzones

Today 110 people attended the Thai GCSA meeting at The Vintage Club near Bangkok. I gave a presentation on Putting Green Management and Putting Green Performance. This dealt with the main reason for poor performance of sand-based putting greens – the accumulation of too much organic matter.

The presentation slides can be downloaded here.

In my talk, I first mentioned the three main problems we have with turfgrass surfaces that are wet and soft because of too much organic matter in the soil.

1. Mowing cannot be done properly and low mowing heights are impossible to obtain without scalping the turf.
2. Ballmarks are excessively large and general playability of the course is not at an optimum.
3. The probability of fungal diseases is increased.

I shared some data collected over the past year that shows an increase in soil moisture in a sand rootzone will usually lead to softer surfaces. We looked at a clip from a classic video of water movement in soils, to see what happens as water moves from a relatively fine-textured (sand + organic matter) layer down to a coarse-textured (sand without organic matter) layer, and then we discussed the four ways in which we can manage soil organic matter. Of these, I think the first two are the most important.

1. Manage the growth rate of the grass to avoid excessive accumulation of organic matter, allowing the grass to grow at a rate sufficient to recover from traffic damage, but no faster.
2. Apply sand topdressing to dilute the organic matter as it is produced. As a general rule, plan to apply at least 0.012 m³ sand/m²/year.
3. Verticut (vertical mowing down to the soil surface) and scarify (vertical mowing that goes below the soil surface) to remove organic matter.
4. Core aerify to remove organic matter, keeping in mind that tine size and tine spacing should be carefully considered to optimize the organic matter removal at each time of aerification. This will minimize disruption to golfers.

I would like to thank the TGCSA for inviting me to speak today and for all the superintendents who attended. I spoke at a TGCSA seminar at The Vintage Club when I was just starting with the Asian Turfgrass Center in 2006, and it was fun to be back six years later, with about twice as many people in the room, to be presenting about things that we have learned, based on research conducted here in Thailand and in other parts of Asia.

For more information, see these documents:

A Report on Putting Green Performance Characteristics (Woods, 2012, Asian Turfgrass Center)

Aeration and Topdressing for the 21st Century (Hartwiger and O'Brien, 2003, Green Section Record)

Cultivating to Manage Organic Matter in Sand-based Putting Greens (Landreth et al., 2007, USGA TERO)

Correcting A Common Misapprehension About Seashore Paspalum

After a month of research and writing at Japan, I've returned to Thailand, gotten my mail, and in that accumulated stack of papers I found (and promptly read) the July 2012 issue of Golf Course Architecture. 

In that issue, in a report on Morocco's Mazagan Golf Resort, Adam Lawrence wrote that the course is a genuine links in soil, topography, and design, but noted that the course does not, with its seashore paspalum turf, provide the kind of surface that a course like that requires. 

Lawrence then went on to write that:

Paspalum is capable of delivering a fast and bouncy surface, but it needs to be kept dry and lean, or it becomes 'sticky', with chip shots catching in the fringes, and an aerial approach the only sensible option.

This is not the first time I have heard that seashore paspalum should be kept dry and lean, but I would be remiss if I did not point out that such a maintenance strategy does not work with seashore paspalum. 

Lawrence is correct that seashore paspalum is capable of delivering a fast and bouncy surface. But that surface is realized only when seashore paspalum is mown short, like a putting green, and when sand topdressing is regularly applied, like the maintenance for a putting green. Dry and lean means that growth is restricted by a lack of water and by a lack of essential nutrients. Dry and lean works to produce a firmer surface with bermudagrass, or with zoysiagrass (see below), but for seashore paspalum dry and lean leads to failure, and the effective approach, albeit a costly one, is to maintain the surfaces more like a green, namely with low mowing heights, frequent mowing, and regular sand topdressing.

Starting to get dry, like British Open dry. Nice that the zoysia will just come right back when the weather breaks. twitter.com/alban3074/stat…

— Albert Bancroft (@alban3074) August 27, 2012

Here we can have a look at seashore paspalum that is fast and bouncy, topdressed as if it were a putting green, mown at less than 6 mm, and definitely a surface on which the ball skips forward.

Keeping paspalum dry, as Lawrence has suggested, will make the paspalum firm – once – but as a regular maintenance strategy it leads to seashore paspalum being overtaken by bermudagrass or other grasses and weeds. Here we see seashore paspalum maintained dry, and it is undoubtedly firm and bouncy, but it is also dying and the green bermudagrass grows right over the dormant seashore paspalum.

This problem is seen, as far as I know, on every golf course planted to seashore paspalum. In an interesting experiment at the University of Georgia, seashore paspalum plugs, and bermudagrass plugs, were planted into soils with pH of 4.2 and of 6.5 on 30 June 1998. For the first 24 days after planting, good soil moisture was maintained. After that, no irrigation was applied. Fertilizer was applied just twice, for a total N application of just 10 g N/m² for the 53 weeks the experiment was underway.

And what were the results of this experiment in keeping the grass dry and lean? At pH of 6.5, the common bermudagrass covered 4x as much area, and the Tifway 419 covered 3x as much area, as did the the best of the paspalums, on average. At pH of 4.2, the difference was even more pronounced, with the common bermuda covering more than 13x the area of the top-performing paspalums, and the Tifway 419 covered 6x as much area as did the paspalums.

The results of this experiment are pretty easy to interpret. If you don't apply supplemental irrigation to seashore paspalum, it doesn't grow very much at all.

And of course keeping it lean doesn't help, as we see below, for dollar spot will attack seashore paspalum with a vengeance when it is not kept growing at a relatively rapid rate.

Making seashore paspalum surfaces fast and bouncy requires maintaining them like a putting green, and not, as Adam Lawrence suggested, keeping them dry and lean. The truth is, seashore paspalum is overused, at least on golf courses in Asia, and other grass species can usually be maintained faster and bouncier for a much lower maintenance expense. For more information, see these posts about:

The natural growing environment of seashore paspalum and its implications for turfgrass maintenance (video)

Suggestions on the right maintenance for the wrong grass (from Turf Disease blog)

Why is there cool-season grass in Philadelphia and warm-season grass in Seoul?

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.

Customize the chart yourself to see data for other cities.

Data: korea • Chart ID: ATC_climate_chart_Korea

R version 2.15.0 (2012-03-30) • googleVis-0.2.16
• Google Terms of Use • Data Policy