I made a few notes at the recent Philippine Golf Course Management Conference. I was there to speak about irrigation water and soil test interpretation.

The conference program was excellent and I learned a lot. Things I noted, which will perhaps be of interest:

1. Do you know about this sand calculator from Purdue University?

2. One of the speakers showed how the Turf Tracker improves the precision of product applications to the golf course.

3. I was intrigued by the Zero Carbon Resorts program, and especially the Demonstration Cottage.

4. There was some discussion of the Philippines Köppen climate classification.

I taught two seminars yesterday at the Philippine Golf Course Management conference. The first was about irrigation water requirement. The slides are here, and I made this Shiny app with data from 2013 through 2016 for Manila, Cebu, and Baguio.

In the second presentation I spoke about MLSN after 5 years. I explained what soil test interpretation is, why the MLSN guidelines were developed, and explained how they work.

I was making some calculations today about irrigation water requirement. I looked at Manila, where the normal annual rainfall is 1877 mm, and Cebu, where the normal annual rainfall is 1260 mm. These data from Manila are the 30 year average from 1961 to 1990, and at Cebu a 20 year average from 1971 to 1990.

For my calculations, I was looking at the past 10 years, from 2007 to 2016. I wanted to show the variation in irrigation water requirement at both locations, based on a calculation of the daily soil water balance.

I was able to get the daily precipitation from the GHCN (Global Historical Climatology Network) daily summaries by using the rnoaa package in R. For Manila, the annual precipiation (summed from the daily amounts) for the past 10 years ranged from 1381 mm to 2932 mm, with a mean annual amount of 1908 mm. That's pretty close to the normal of 1877 mm. For Cebu, there wasn't as much rain. The lowest year of the past 10 had 682 mm, the most was 1713 mm, and the mean was 1276 mm. Also pretty close to the normal of 1260 mm.

So what surprised me? Cebu gets less precipitation than Manila. The year with the most precipitation (in the last 10 years) at Cebu still had less rain than an average year at Manila. With those kind of differences, I expected the irrigation water requirement to be more at Cebu than at Manila. It rains less at Cebu, so more irrigation should be required, right?

The calculations don't work out that way. The reason is the way the rain is distributed through the year. Manila has more pronounced dry seasons and wet seasons. Cebu has dry and wet seasons too, but the dry seasons have more rain than at Manila.

For more, see the full presentation.

On a visit to Manila some time ago, I visited a golf course and had a look around with the golf course superintendent. Our discussion turned to seasonal changes in weather and the relative impact on the grass. For example, in the winter, when the temperatures are a little cooler, is it lower temperatures that have a big impact on slowing the growth? Or might it be the light, because the days in winter are a little shorter and the sun is a little lower in the sky?

I made some calculations then, and reran the script now to refresh my memory about this.

I calculated what the photosynthetic light would be on a sunny day in each month.

That's how the photosynthetic photon flux density (PPFD) will be throughout the year when there are no clouds. It varies a bit.

For the total light per day we can look at the daily light integral (DLI), and this is how the DLI changes through the year.

The PPFD is how much light reaches the turf every second. Adding together the light from each second, from sunrise until sunset, gives the total amount for the day -- the DLI.

What about temperature? Manila is 13 degrees north of the equator with a tropical climate. The coldest month is January, with an average temperature of 25.6°C. The hottest month is May, with an average temperature of 29.5°C. That's a difference of 3.9°C from the coldest to the hottest month.

The sunny day DLI ranges from about 44 to 59 mol m^-2 d^-1. So which changes more, the temperature, or the light?

To look at that, I plotted the standard score (z-score) for the DLI and for the temperature across 12 months. The z-score shows how many standard deviations a value is from the average (mean).

If the z-score is less than 0, that means the value for that month is less than the average for the year. If the z-score is more than 0, that means the value for that month is more than the average for the year.

Because the z-scores are standardized, I can compare directly the DLI and the temperature, and how much they are changing in any one month, compared to their average value during the year.

At Manila on sunny days, the temperature varies relatively more than the light in January, February, April, and May. In March, and from June through December, the light varies relatively more than the temperature.

... 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.

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.

I was excited to read the press release from AGIF and GCSAA last week announcing that Beth Guertal will be teaching in September at events in the Philippines and Vietnam. I've always enjoyed studying the research she does, and these seminars are a great opportunity for learning from one of the world's experts on turfgrass management. 

I'm not sure that she will be talking about these particular experiments, but these are three of my favorites (of the many) from her research group.

1. Fertilization of bentgrass with commercial foliar products: Greenhouse evaluations. "In most cases foliar application of urea was as effective (for N uptake and dry matter yield) as applying any of the commercial materials."
2. Potassium Movement and Uptake as Affected by Potassium Source and Placement. "Over the 2 year study potassium application had no beneficial effects on turfgrass performance, and acceptable performance was achieved across a wide gradient of K content in soil and leaf tissue. Regardless of soil test K level, no deficiency symptoms were observed."
3. Fan and syringe application for cooling bentgrass greens. "In general, reductions in the maximum observed temperature occurred in the following order: fan plus syringing, fan only, syringe only, and, no fan/no syringe."

ワクワクの名物8番Par3 グリーンに乗らないと地獄です！ pic.twitter.com/liQ8ABKY0B

— Yoshinobu TSUKADA (@GoBirdie) May 13, 2014

The Asian Tour is at the East Course of Wack Wack Golf and Country Club this week for the Philippine Open. This photo from pro Yoshinobu Tsukada is the par 3 8^th, one of the classic short holes in Asia. One notices a lot of trees, with just a narrow corridor for play.

In a tropical climate, trees and shade can be a desirable feature on the golf course. Shade is certainly welcome, at least from the players' point of view.

Caddies and golfers at Bangsai CC north of Bangkok use umbrellas to provide shade on a sunny summer day

Not all grasses can handle the shade from clouds, combined with the shade from trees. At Wack Wack's East Course, there is manilagrass on the greens, and tropical carpetgrass on fairways and rough. These grasses, tropical carpetgrass (Axonopus compressus) and manilagrass (Zoysia matrella), are the two species that can tolerate low mowing (less than 5 mm) under appreciable tree shade in a tropical climate.

If one wants to have grass, and have trees, then these are the grasses that work. And they require minimal inputs, can be mown as short as one likes, and they can be maintained to the highest level for international tournaments.

These species also work on the local courses that want to have good playing conditions, but may not have an irrigation system, or a big budget. 

The 1st at Khet Udom Sak GC in Chumporn, Thailand: manilagrass greens, carpetgrass through the green, no fairway irrigation

 And when it rains, these species can handle the tropical rains just fine. But most importantly, they are the species that tolerate low mowing in tree shade in a tropical environment. For more info, see the links immediately below this post.

The 7th at Pakasai CC in Krabi, Thailand: manilagrass greens (3.5 mm), carpetgrass through the green (8 mm on surrounds)

Related articles

Shade and the Performance of Warm Season Grasses in Asia

My View About Grass Selection on new Golf Course Management website

Turfgrass Mystery: what grass is this?

Manilagrass is the best choice for links-style golfing surfaces in East and Southeast Asia

Various interesting posts hide in the back pages of blogs, and I've enjoyed seeing which of the posts from the early years of this blog were most popular, as measured by the number of pageviews.

Continuing with the lists of top posts by year since the inception of this blog in 2009, here are the 5 posts with the highest pageviews from 2011:

1. An Interesting Technique to Modify Fairway Conditions in Thailand
2. Sandcapping or topdressing: which is better?
3. A Report From the 2011 Golf Course Maintenance Management Conference
4. Research on Weed Populations in Malaysia
5. How Much Potassium Does Turfgrass Need?

I previously listed the 5 top posts from 2009 and the top 5 from 2010.

Continuing with the lists of top posts by year since the inception of this blog in 2009, here are the 5 posts with the highest pageviews from 2010:

1. What Fertilizer is Best for Zoysiagrass?
2. China Golf Show 2010 at Beijing
3. Golf Course Renovation, Grass Selection, & Manilagrass
4. Guidelines for Tropical Turfgrass Installation and Management
5. Turfgrass Performance Data at the Open Championship

I previously listed the 5 top posts from 2009.

At the Philippines Turfgrass Forum on 1 August, I spoke about Five Easy Ways to Improve Turfgrass Performance. The presentation slides are available for download as a 9.3 MB PDF file, and UPLB Research, Development, and Extension have recorded a video of the presentation and made it available to the public.

In the presentation, I talked about the management, selection, and optimization of mower adjustment, grass variety, soil moisture, soil organic matter, and nitrogen application rate as being the five things, all interrelated, that when moved closer to optimum management will be sure to produce improved turfgrass. Watch the video here (20 minutes).

Related articles

Presentation Video: Minimum Nutrient Requirements for Putting Green Turf

Report, Handout, and Presentation Slides from the Philippine Turfgrass Forum

The Global Soil Survey for Sustainable Turf, a new citizen science project

Does extra potassium improve bermudagrass performance when soil sodium is high?