My (turfgrass talk) column in the March/April issue of GCM China discusses water in the soil. I wrote about the amount of water that is held in the soil and how the amount of water expressed as a percentage can be converted to a volume of water.
The temperature-based turfgrass growth potential predicts how grass growth can respond to temperature. This growth potential (GP) was developed by PACE Turf and has been put to many uses such as predicting the time of overseeding, estimating turfgrass nitrogen requirements, assessing turfgrass stress, and evaluating growth and optimum times for various maintenance practices.
When the temperatures are not conducive to growth for cool-season (C3) or warm-season (C4) grasses, there isn't much one can do to force the growth. Extra nitrogen can be added, but it really doesn't have its full effect until the temperatures get into an optimum range for growth.
After reading that tweet, I looked up the temperature data for Tulsa. Sure enough, the growth potential for C3 grass has been pretty low for the past month. Growth potential of C3 and C4 grasses at Tulsa are plotted in this chart, with data included for the past 472 days, from 1 January 2013 until 17 April 2014.
I find the growth potential useful in a lot of ways. On golf courses with both cool and warm season grass, as at Bristol Hill Golf Club near Kisarazu, it can be useful to study the growth potential when planning maintenance activities.
Cool season (C3) and warm season (C4) grass at Bristol Hill Golf Club near Kisarazu, Japan
The GP at Kisarazu for the past 472 days is show below. Ideally, disruptive maintenance practices such as scarifying or core aerification will be done at times when the turf has a high growth potential. This allows for a rapid recovery time and minimizes disruption to play.
I looked up the data for a couple other cites. At Sydney (data from the Sydney Airport), the temperatures are milder.
At Dubai, the temperatures are more extreme.
With all the variation in temperature from place to place, there is also a big difference in the way grass will respond. The growth potential puts a numerical value to this. This can then be used in maintenance planning, in useful comparisons to other locations, or in explanations of why the turf is responding in a certain way.
Last week at the Vancouver Island Golf Superintendent Association meeting, I spoke about turfgrass nutrient requirements. The question a turfgrass manager must answer is this one: Can the soil supply enough of an element to meet the grass requirements, and if it cannot, then how much of the element must be applied as fertilizer?
The presentation handout and slides contain the detailed answer to that question. The short answer is that we can identify the amount necessary as fertilizer from just 3 numbers:
the amount we have (soil test amount)
the amount we need to have in the soil (the MLSN guideline)
the amount the grass will use
To find how much of each element is required as fertilizer, we look at the total amount that must be present, which is the amount the grass will use (3) added to the amount we need (2) in the soil.
Then we compare that amount required (2 + 3) to the actual amount we have (1). If the amount we have is more than the amount required, that element is not needed as fertilizer. If the amount we have is less than the amount required, that difference is the amount needed as fertilizer. The handout has a full explanation of how to get these numbers.
Last week I read two contrasting things about potassium and Microdochium nivale (fusarium patch or pink snow mold).
In the March Greenkeeper International, this article about fusarium patch instructs one to:
Feed turf by all means - but with fertiliser formulations rich in potassium to make the most of the ‘gatekeeper’ nutrient with its intrinsic abilities in good water relations and strengthening of grass plant tissues.
There was also this, from Doug Soldat, showing an interesting result in which M. nivale was increased by potassium application:
When it comes to potassium application, one should not think that adding potassium will always "strengthen" the plant or improve resistance to diseases. Eliminating a potassium deficiency is almost always a good thing. Eliminating the deficiency will improve root growth, increase leaf growth, and ensure that the grass is able to function normally. Adding potassium beyond the amount required to eliminate the deficiency may cause problems.
Last year in March I wrote this post about perceived divot problems on manilagrass (Zoysia matrella) tees. To summarize, I've heard many objections (in theory) to the use of manilagrass on tees in Southeast Asia, the thought being that manilagrass grows slowly and divot recovery may be too slow for this grass to be suitable on tees.
On this topic, it is relevant to consider the approximately 1,800 golf courses in Japan with manilagrass tees. Those tees are played for almost half the year when the grass is dormant. The grass cannot recover from divots at all during that dormant period, yet it still produces an excellent tee surface. If this grass can be used to produce excellent tees when it grows for only half the year, one expects that manilagrass will do just fine on tees in Southeast Asia where it never goes dormant.
Tee at Keya GC Hole 12 in mid-March 2014 after more than 19,000 rounds on dormant manilagrass, photo courtesy of Andrew McDaniel
Manilagrass tees, even on a heavily used par 3, as shown above, still have a lot of grass after an autumn, winter, and spring of play on the dormant turf. Soon after the grass starts growing in April, the tee will be almost 100% grass, with nary a divot to be found.
Muang Kaew GC in Bangkok has about 72,000 rounds every year. During the peak season, 220 golfers play every day. The manilagrass tees never go dormant, nor do they suffer from severe divoting problems.
Manilagrass tee on Par 3 #17 at Muang Kaew GC in Bangkok
The most-heavily divotted area of the par 3 17th at Muang Kaew GC in Bangkok
With any grass on tees, especially on busy golf courses, it is important to control the traffic. On seashore paspalum (Paspalum vaginatum) tees at Siam CC near Pattaya, the divots are concentrated on one section of the tee to allow other areas to recover. By starting at the left front of the tee and moving the tee markers back about 50 cm every day, the golfers can always tee off from divot-free grass, and an entire tee of this size can be apportioned into about 42 sections, giving 6 weeks recovery time before returning to a previously-used location.
Divots on a par 3 tee of seashore paspalum at Siam CC near Pattaya; careful movement of the tee markers gives about 6 weeks recovery time before the same area of the tee will be used again
In the article, I wrote about 4 things these guidelines are designed to do:
To ensure the grass is supplied with enough nutrients.
To ensure that excessive amounts of fertilizers are not applied.
To allow for calculation of a sustainability index for each nutrient, comparing the amount of a nutrient in the soil at a site to the distribution of that nutrient in a wide range of turfgrass soils.
To be continually updated and shared as new information is added to the dataset from soils around the world.
The MLSN guidelines are unique among turfgrass nutrient guidelines in that they are explicitly site-specific. By looking at the estimated plant uptake of nutrients for a particular site, comparing that to the amount of nutrients in the soil, and then checking to make sure the amount remaining in the soil will be at or above the MLSN guideline, this approach is a simple, logical, and rigorous approach to understanding turfgrass nutrient requirements.
For more information on the MLSN guidelines, the Global Soil Survey, and turfgrass nutrient requirements, see:
I had thought the fans in the tea fields of Shizuoka were used to reduce fungal diseases of the foliage during hot and humid weather. Yesterday I learned that the actual reason for these fans is to prevent frost from forming on the leaves during winter, by blowing warmer air (cold air is heavier, and sinks) down to the plants.
These same fans are used on many golf courses in Japan to improve air movement across creeping bentgrass greens during summer.
The fans are usually painted brown and are kept relatively distant from the green surface, blending right in with the pine trees around the green. These tea fans (o-cha senpuki) are also quiet, and I've been assured by Japanese greenkeepers that they do cause a noticeable improvement in bentgrass greens, without causing too much disturbance to golfers.
This morning I visited a golf course with a great view of Mt. Fuji. This view will be really stunning in a few days when the cherry trees are blooming.
There are 72 holes (4 courses, each of 18 holes) run out of 1 maintenance facility here, and I was reminded of just how much work is involved in the maintenance of these facilities. Of the 72 holes, 54 of them (3 courses) use the two green system. Only 1 of the courses uses the one green system. And these are not summer and winter greens, they are all creeping bentgrass.
So for 72 holes, there are 126 greens to maintain, plus the practice greens. And this is all done with a maintenance crew of less than 50 people. I'm often impressed at the conditions produced by turfgrass managers the world over, and today I was impressed again.
For more about course maintenance in Japan and the two green system, see: