Viridescent - the Asian Turfgrass Center blog

Calcium for Turfgrass: is there enough in the soil?

The answer, almost certainly, is yes. These calculations of how much calcium the grass uses, compared to how much plant-available calcium is in the soil, leave little doubt that there is almost always more than enough calcium in the soil to meet the needs of the grass.

How much calcium does grass use?

Let's take a turfgrass site at which clippings are removed, and estimate how much calcium is removed, or harvested, in one year. A reasonable estimate for annual clipping yield of maintained turfgrass is about 400 g m^-2. A reasonable estimate for calcium in the dry matter of turfgrass clippings is about 4500 ppm = 4.5 g kg^-1 = 0.45%. So if we harvest, over the course of a year, 400 grams of clippings from each square meter, and if those clippings contain on average 0.45% calcium, then the mass of calcium harvested from one square meter each year is:

400 g x 0.0045 = 1.8 grams of calcium removed each year

How much calcium is in the soil?

We've just calculated that in the situation where we remove the clippings from a maintained turfgrass area, we may be removing about 1.8 grams of calcium from each square meter each year. Let's now imagine that our root system is 10 cm deep, and that the bulk density of the soil is 1.5 g cm^-3. In one square meter, then, to a depth of 10 cm, we have a volume of 100 L, and a mass of 150 kg. Let's say this is a sandy soil, with a relatively low cation exchange capacity, and that the plant-available calcium (the calcium that is in soil solution and on cation exchange sites) is at a concentration of 400 ppm = 400 mg kg^-1. How much calcium is that?

150 kg of soil x 400 mg/kg = 60,000 mg of calcium = 60 g of calcium

Three Decades

That's how long it would take, 33.3 years, to be precise, for the grass to use 60 grams of calcium if harvested at the rate of 1.8 grams of calcium per year. There is much more calcium in the soil than is required for healthy turfgrass, even in soils that have relatively low amounts of calcium.

World Cities Plotted by Climatological Normals, February

February is another good month, on average, to grow grass in Bangkok, Chennai, Colombo, and Mumbai. Why? With average temperatures more than 25°C and sunshine well above 200 hours for the month, the growth of warm-season grasses can easily be controlled by turfgrass managers through adjustments in the amount of water and nitrogen applied. 

Hainan Island is sometimes referred to as the "Hawaii" of China, but Sanya is considerably cooler and has a lot less sunshine than does Honolulu in February. For about six months of the year, Sanya is a lot more like Hilo than Honolulu, and that means slightly cooler temperatures and significantly less sunshine. 

Research, Teaching, and Speaking in Tennessee

I visited Tennessee this month, speaking at the packed Tennessee Turfgrass Association conference, meeting with faculty in the Plant Sciences Department at the University of Tennessee (of which I am an adjunct faculty member), learning about some of the turfgrass research projects now underway at the University, and teaching this semester's first session of the Turfgrass Rootzone Construction and Management course.

I participated in a panel discussion with Rodney Lingle (Memphis CC), Matt Shaffer (Merion Golf Club), and Chris Hartwiger (USGA Green Section) in which we discussed ultradwarf bermudagrass management, preparation for the 2013 US Open, cold tolerance of bermudagrass, and heat tolerance of creeping bentgrass. I gave three other presentations at the conference, on topics ranging from course preparations for the Open Championship, fertilizer for sand rootzones, and turfgrass management in Asia. The attendance at the conference was superb. In fact, for many of the presentations it was standing room only, and the trade show was bigger than I had expected too.

At the University of Tennessee I saw the now completed Center for Athletic Field Safety with some really great looking synthetic surfaces along with natural turf. This impressive facility is being used for some cutting-edge research about sporting surfaces, biomechanics, and athlete safety.

I saw a lot of other research as well -- zoysia trials, lots of weed control work, many with the new herbicide indaziflam, rooting experiments, seedhead control of zoysia -- suffice it to say that there is a lot of interesting information being developed by the turfgrass team at the University of Tennessee.

We also discussed turfgrass educational programs in Asia and weed control in India for upcoming sessions of the Indian Golf Union's Greenkeeper Education Programme.

At the end of my week in Tennessee, I taught the Plant Science 442 course, Turfgrass Rootzone Construction and Management. I talked about sand rootzones, why we do core aerification (coring, hollow-tine aerification), and what some of the challenges are in managing turf in sand rootzones. I spoke, basically, about these topics:

• Managing the rootzone (handout from Sustainable Turfgrass Management in Asia 2010)
• Managing the rootzone (presentation slides from Sustainable Turfgrass Management in Asia 2010)
• Do fairways need a sandcap? (article from Asian Golf Business)

Potassium for Turfgrass: interview with Dr. Larry Stowell of PACE Turf

Dr. Larry Stowell and I recorded this video interview about potassium fertilizer for turfgrass. How much potassium is enough? How should you decide how much potassium to apply to meet the plant requirements, without wasting money by applying too much? Is potassium fertilizer necessary at all? Watch this video to find out, and check out PACE Turf for a wealth of valuable turfgrass information.

World Cities Plotted by Climatological Normals, January

This chart shows a selction of world cities, plotted by average temperature, sunshine, and precipitation for the month of January. Bangkok, Chennai, Colombo, and Mumbai look like splendid places this month, at least for the growth of warm-season grasses. It will normally be warm, sunny, and dry in these cities, allowing turfgrass managers to control the growth with fertilizer and water applications, without concern for a lack of sunshine. 

World Cities Plotted by Annual Climatological Normals

On these charts, a selection of world cities are plotted according to their average annual temperature and average annual sunshine hours, with the size of the bubble for each city proportional to the average annual precipitation. The display of information in this way allows us to identify quickly some differences between the normal climate in different locations. Miami and Honololu, for instance, are very similar in average annual temperature, and almost the same in sunshine, but Miami has much more rainfall than Honolulu. 

The charts are shown with the x and y axes going to zero in the plot above, to get some sense of the range of variation in the data, and in the chart below the data are plotted to fit the chart, so that we can more easily identify the location of the cities. Atlanta has a similar annual temperature to Osaka, and similar precipitation, but there are about 40% more sunshine hours in Atlanta each year than in Osaka. That difference is clearly something to consider if we think about how, for example, ultradwarf bermudagrass greens would perform, or should be managed, in those different locations. 

Photosynthesis is affected by temperature, light, water availability, and leaf nitrogen content. Turfgrass managers control the nitrogen by judicious application of fertilizer, and the water availability is controlled partly through precipitation and partly through supplemental irrigation. Light and temperature, then, stand out as the uncontrollable influences on photosynthesis. In the warm-season areas of the United States, there tends to be relatively high sunshine. It is normal to have 2500, 3000, or even 3500 sunshine hours in a year. So in the United States, much of the grass selection, when it comes to warm-season (C₄) grasses, is just a matter of temperature -- "is this a warm-season area, by temperature, or not?" 

In Asia, there tends to be less sunshine. If we compare Hong Kong with Miami, we see that Miami is slightly warmer, and Hong Kong has a bit more precipitation, but there is a huge difference in sunshine hours, with Miami having on average about 70% more sunshine hours than at Hong Kong. Does this have an affect on turfgrass performance? Yes! We see Zoysia matrella thriving in Hong Kong, and Singapore, and Tokyo, all cities where the sunshine hours are relatively low. Bermudagrass, on the other hand, performs relatively poorly in these same cities, and requires special care to keep in a playable condition. 

Why "Liquid" Fertilization is Better Terminology than "Foliar" Fertilization

When applying fertilizer to turfgrass plants, there are two general types of application: liquid and granular. Granular products are applied in a dry form, while liquid products are applied as a spray application.

The term foliar fertilization is often used to describe liquid applications made to the leaves, or foliage, of turfgrass. But this can be misleading,with the implication that all the applied fertilizer is being taken up by the foliage. 

The reality is that only about 50% of the fertilizer applied to turfgrass foliage enters the plant through the leaves. And in many cases much less than 50% is absorbed by the leaves. Recent research by Branham et al. found that 14 to 37% of the applied nitrogen was taken up by turfgrass leaves in Illinois. Research at Arkansas by Stiegler et al. found uptake of 36 to 69% of foliar-applied nitrogen. These results are similar to the experimental results of Professor Jörg Schönherr who has done extensive research into foliar uptake of nutrient ions. Uptake is the highest at 100% humidity, so once the liquid solution has dried on the leaf, foliar uptake of the applied nutrients ceases. 

Even with the limited foliar uptake, I still prefer liquid applications to granular applications. With liquid applications, precise doses of nutrients can be spread evenly at low rates to all areas of the sward. It is impossible to get such even distribution of nutrients when applying granular products. 

When I was the superintendent at Shanghai Links, we made liquid fertilizer applications to all areas of the course as the main source of nutrients. We would allow the fertilizer to dry on the leaves, so we would get some uptake by the foliage, and we would then apply enough water to rinse the remaining fertilizer from the leaves and into the upper reaches of the soil, where the remaining nutrients could be absorbed by the roots.  

List of Climate Charts: China, India, Japan, and Global

I've made many climate charts this year, from the static ones that can be downloaded and printed, to the interactive ones that can be viewed and modified in a web browser. This is a list of all the charts that are available, starting with the interactive ones that show the changes in normal temperature, rainfall, and sunshine hours through the year.

Climatological normals for 50 world cities

Climatological normals for 46 world cities

Climatological normals for major Chinese cities, in English

Climatological normals for major Chinese cities, in Chinese

Climatological normals for major Indian and surrounding cities, in English

Climatological normals for major Indian and surrounding cities, in Hindi

Climatological normals for major Japanese cities, in Japanese

Climatological normals for major Japanese cities plus Atlanta and Bangkok, in Japanese

Climatological normals for Bangkok, Hong Kong, Kolkata, Miami, and Tokyo

I have also made a series of static charts that can be viewed online or downloaded and printed. These charts are from the dataset with climatological normals for 46 world cities.

The static charts were made using the ggplot2 package in R. The interactive motion charts were made using the googleVis package in R.

World Cities Plotted by Climatological Normals, November

This chart shows a selection of world cities, plotted by their average temperature, precipitation, and sunshine hours for the month of November. An interactive and customizable chart with the climatological data is available at this link.

How does November look? Well, at cities such as Bangkok and Mumbai, on average, it looks pretty good for warm-season grasses. The rainy season has ended, sunshine hours are way up, and average temperatures are still close to an optimum for warm-season grasses. The Barclays Singapore Open will be on at Sentosa in November. Temperatures are good for warm-season turf, but look at the sunshine hours! On average, there are only 125 hours of sun at Singapore during November. The Zoysia matrella fairways will be in superb condition, I'm sure, for they thrive in these conditions. The bermudagrass greens will be superb as well, but it takes a lot of careful work to maintain high-quality bermudagrass at Singapore, mainly because of the relatively low light conditions.

Turfgrass Teaching and Research at Oregon State University

Last week I had the opportunity to visit Oregon State University to teach one session of Dr. Rob Golembiewski's Principles of Turfgrass Maintenance class. In the morning lecture, I spoke about turfgrass maintenance in Asia and what some of the distinguishing differences are compared with typical turfgrass management in the Pacific Northwest. In the afternoon, I met with the turf club to discuss internships, career opportunities, and some of the interesting things about working in the turfgrass industry in Asia. 

I also visited the turfgrass research farm and saw the various grasses and experimental trials. Brian McDonald is the research assistant for turf management at OSU and he showed me some of the interesting research being done with fertilizer trials, fungicides, herbicides, mowing and rolling, irrigation, grass variety trials, divot recovery, and even some seashore paspalum research. My interest in turfgrass research started when I did earthworm control and herbicide research at this farm in 1998, just before graduating from OSU. 

The amount of research being done now is impressive and I got to see a lot of Poa annua, perennial ryegrass, red thread, pink snow mold, brown blight -- all grasses or diseases that I don't see all the time when I am working with warm-season grasses. Every time I got down for a close inspection of grass disease symptoms, June the Research Cat came over to say hello. She is, I'm informed, the farm's environmentally-friendly method of rodent control.

For more information about the turfgrass program at Oregon State University, check out www.beaverturf.com.