[Wayne_Kozun]

Is anyone aware of research that has been done on the optimal amount of irrigation required for grass given variables like amount of precipitiation, expected preceipitation, temperature, amount of sun, etc?  Is this something that courses use in determining how much they should be watering.

My interest on this subject is more for residential purposes as the Internet of Things is becoming a reality and "smart" residential irrigation controllers can be devices on your LAN that can rely on information from the internet, like weather forecasts and data not unlike the Nest Thremostat.

[Brett Morris]

Wayne,

There have been a few studies on drought tolerance of turf species, but there are too many variables in applying a broad number to specific sites.

In recent years the introduction of soil moisture sensors has assisted water application and management greatly.  On my warm season greens I used to try and keep a percentage of around 12 - 15% to promote firmness, oxygen, etc.  However this may not be applicable to other sites which may have different levels of play, weather, shade, etc.  I corresponded with a PGA Tour agronomist in the leadup to an event played on warm season greens and their numbers in advance week and through the event were in the mid-20% range.

Irrigation systems now are very advanced with on-site weather stations which provide a daily ET figure.  Depending on how the system is setup, you can use that figure to calculate run times for each sprinkler head, on the proviso that individual head data has been inputted into the central, such as slope, shade, soil, nozzle, etc.  It also takes into account rainfall and can automatically shut the system down if a threshold is passed.

There's a lot to it, but regular visual monitoring is still paramount.  Particularly as seasons change.

[Wayne_Kozun]

Thanks Brett.  I was more wondering about this for controlling my irrigation system at home and coming up with an algorithm to use for a web connected irrigation controller.  But I guess soil moisture sensors make a lot more sense.

[Tom_Doak]

The book I've been reading, Antifragile, describes how many natural things are better off with a random diet and periods of starvation, instead of the steady recommended daily allowances of everything.  The author points out that this is the nature of eating what you hunted back in prehistoric times, and that many religions had managed to build it into their belief system with prescribed periods of fasting, etc.

It occurs to me reading the initial post here, that the same would be true for irrigation.  Grass is naturally adapted to random periods of rain, and it becomes stronger and healthier when subjected to the occasional drought.  Thus, computer-controlled irrigation designed to "smooth out" the irrigation curve and optimize the amount of water available to the plant, is probably detrimental over the long run.

[James Bennett]

Wayne

What sort of grass are you using?  soft eg bent or warm eg bermuda or ??
What sort of weather are you dealing with?  Los Angeles droughts, or Philadelphia humidity, or whatever Texas gets or ??

I live in Adelaide with a climate similar to LA.  If I have warm season grasses, I am trying to manage a daily evaporation rate of about 7mm with negligible rainfall.  If I get a heat wave, that 7mm gets to 15mm.  The warm season grasses seem to need about two-thirds of the daily evaporation rate.  So, if I were to water twice a week, I would need to put down (7 days x 7mm x 70%) divided by two which is about 17mm. 

If a heatwave struck, I might need to do an extra water that week.  Plus I may apply a really light syringe late afternoon, just to moisten the surface and allow the turf to cool off.  Not enough to wet the soil underneath.

Hope this helps.  Having healthy turf before the onset of hot summer droughts helps.  Healthy doesn't mean green and sappy though.

James B

[Brett Morris]

Tom,

In theory, yes.  However the newer forms of ultradwarfs don't tend to exhibit as long or as dense a root system.  Many Superintendents tend to give those greens a light amount of water nightly or every other night.

A much more even and consistent level of oxygen within the profile exists with regular light watering.  The irregular deep approach tends to lead to peaks and troughs.  This is on a sand based profile.

[Bradley Anderson]

Dr. Kevin FRank has been doing some very interesting research at Michigan State. He set up three models of irrigation.

1. Deep and infrequent soaking irrigation
2. Light daily irrigation to replace 80% of moisture loss for that day
3. A variation of the 1 and 2

The bottom line is the infrequent model used twice as much water as the daily 80% of return model. This was a surprise even to Dr. Frank.

At my own golf course I have 5 million gallons capacity of water storage. And that's all I get for the entire year (about 30% of what most midwestern course use). I have been following the light daily model at 50% replacement of loss and it is working to maintain just enough moisture and firm conditions.

[Tom_Doak]

Tom,

In theory, yes.  However the newer forms of ultradwarfs don't tend to exhibit as long or as dense a root system.  Many Superintendents tend to give those greens a light amount of water nightly or every other night.

A much more even and consistent level of oxygen within the profile exists with regular light watering.  The irregular deep approach tends to lead to peaks and troughs.  This is on a sand based profile.

Well, I guess if we mess with Nature hard enough, natural solutions don't work.  Sounds like a mess waiting to happen, though.

[Wayne_Kozun]

What sort of grass are you using?  soft eg bent or warm eg bermuda or ??
What sort of weather are you dealing with?  Los Angeles droughts, or Philadelphia humidity, or whatever Texas gets or ??

In my instance this is just for my home lawn which I believe is likely a mixture of rye, bluegrass, etc and I live in Toronto where it does get humid.  I have just bought a irrigation controller that you can control over your smartphone or with computers and I was wondering if there was some sort of algorithm that I could implement to iotimise the watering of my lawn.

[Bradley Anderson]

Wayne,

You will have to do some research to find out where your closest  department of agriculture evapo-transpiration data is collected. Toronto might be one of those regions where the rates don't vary much from day to day. In the Chicago area we are able to monitor our ET from the department of agriculture in Wisconsin and Illinois. Our rates can swing .20 of an inch from one day to the next.

http://agwx.soils.wisc.edu/uwex_agwx/sun_water/et_wimn
http://www.isws.illinois.edu/warm/soiltemp/displaymap.asp?data=evap#toptitlebar

You don't necessarily need your own weather station to be accurate. After you find a data source you will need to tweak your system for a percentage of replacement. That all depends on soil type, grass species and exposure (e.g. shade, slopes). You will need to know the precipitation rate of your sprinkler zones.

Eventually this data will interface directly with the computer systems that home owners, institutions and industrial parks use to program their irrigation systems. It could even be set up to account for slopes, soil types and grass types. The data gird is already out there, it just needs to be made available.

If I was a turfgrass researcher I would be all over this. I would make it available for a fee that would raise money for turf research. Then I would take the credit for saving millions of gallons of water. HINT HINT  

[Steve Okula]

The book I've been reading, Antifragile, describes how many natural things are better off with a random diet and periods of starvation, instead of the steady recommended daily allowances of everything.  The author points out that this is the nature of eating what you hunted back in prehistoric times, and that many religions had managed to build it into their belief system with prescribed periods of fasting, etc.

It occurs to me reading the initial post here, that the same would be true for irrigation.  Grass is naturally adapted to random periods of rain, and it becomes stronger and healthier when subjected to the occasional drought.  Thus, computer-controlled irrigation designed to "smooth out" the irrigation curve and optimize the amount of water available to the plant, is probably detrimental over the long run.

Grass did indeed naturally adapt to random periods of rain and drought. During the same evolution, it adapted to growing to its full height and occasionally being munched off by some ruminant.

What grass never adapted to was being mowed two, three, or seven times a week to heights of a tenth of an inch. That's only been happening really in the past 100 years or so. Sports turf, and especially golf course turf, is forced into what for the grass is a most unnatural condition, and golf course superintendents need to adapt feeding, watering, and pest control accordingly.

Itis absurdly easy to grow grass with no inputs, bur technically challenging to grow grass suitable for golf.

[Tony Ristola]

The book I've been reading, Antifragile, describes how many natural things are better off with a random diet and periods of starvation, instead of the steady recommended daily allowances of everything.  The author points out that this is the nature of eating what you hunted back in prehistoric times, and that many religions had managed to build it into their belief system with prescribed periods of fasting, etc.

It occurs to me reading the initial post here, that the same would be true for irrigation.  Grass is naturally adapted to random periods of rain, and it becomes stronger and healthier when subjected to the occasional drought.  Thus, computer-controlled irrigation designed to "smooth out" the irrigation curve and optimize the amount of water available to the plant, is probably detrimental over the long run.

In that vein, but not directly associated with irrigation:

What is your biggest challenge?
It's evolved over six years. When I started, it was the fungus diseases that were the most
problematic. With our cultural practices and the organic fungicides that we use, the
disease severity is a lot less than it was. We also think -- not proven, totally anecdotal --
that there's some natural selection going on. We think the grasses are beginning to adapt.
It's survival of the fittest -- disease-resistant grasses occurring naturally. We've seen some
areas over the years that have got really hit hard with dollar-spot fungus one year, then in
subsequent years we don't see it at all. We've seen it even in greens. Kind of interesting.

By not spraying with traditional synthetic fungicides, you're saying that perhaps you're
allowing the grass the chance to heal itself. An analogy would be using penicillin
constantly and compromising your body's natural immune system. It's an interesting
thought. Ten years ago or so I remember hearing a story about some bent-grass research
plots where they were testing for various fungal diseases and different fungicides. Then
the research ended, and they closed the field down and just let the plots go. They didn't
do anything to them for a year. And when they came back, all the plots where they had
been spraying fungicides had dollar spot all over them like you can't believe. But there
was a control plot that during the research they didn't do anything to. And when they
came back, the control plot was fine.

Source: http://www.vineyardgolf.com/upload/custom_screens/this/vineyard/10_GolfDigest_May2008_TheGolfCourseSuperintendent_%20JeffCarlson.pdf

[Mike_Young]

If one were to take all of the money spent on industry promoted irrigation products, herbicides, mowing equipment and and hired a good superintendent instead they would end with a better product and save considerably and have a better product.

[Bradley Anderson]

One of the great misconceptions about turf grass is being touched on here: the idea that grass will adapt or evolve with the pressures exerted through management and environment.

The DNA of perennial turf grasses do not change. Poa annua on the other hand is an annual plant with a prolific seed population; it can adapt to the environment and to your management practices. Bent grass could probably adapt as well, but it won't produce a seed head until you let it grow above 2-3 inches - not very practical on a golf course.

But all that said, adaptation is an observable phenomena. Where it is happening however is in the soil. If you manage your soil for optimum microbial activity, balanced fertility, water and air movement, together with organic matter mitigation (aeration and topdressing), you will be able to reduce your management inputs.

Poa annua won the adaptation battle on older greens because those older bent varieties were selected for their ability to generate 4-7 leaves per shoot when mowed at 1/4". But when green speed expectations forced a lower mowing height, those older grasses could only produce 2-3 leaves per shoot. Poa annua won the turf war. Then when you added the effects of shade trees being planted too close to greens, and bunker sand accumulations blocking the surface drainage routes, the Poa gained complete control of the situation. Even the newer varieties of bent grass, bred for lower cutting heights, could not make the adaptation to shade and prolonged surface wetness. Poa did adapt to shade and wetness.

We keep pounding seed and Poa control chemicals on these old greens and just when we think we have turned the corner a nasty winter comes along to show us that we still have a Poa problem.

[Bradley Anderson]

The above article illustrates that the bent grasses that were propagated on the older greens were not bred, rather they were selected from the best sections inside of the original greens that had been seeded with South German bent seed before the war.



The above picture shows that the cutting heights during the selection process were very high.

These grasses were propagated on to greens using vegetative stolons from the best selections. Using that method of propagation, every plant was genetically identical. This made adaptation of bent grass even less likely because the entire community of grass was identical. You did not have a situation where a mongrel strain in the bent grass community was better adapted to lower cutting heights, hence colonizing the other grasses around it.

Some of the very old greens did have mongrel varieties of bent making the transition to lower cutting heights, but even those are mostly gone now.

[Steve Okula]

Bradley,

Good post and thanks for those articles. Do you have a date for the first one?

I find it interesting that in the second article, dated 1933, there is mention of green speed. Though not then quantifiable with a stimpmeter, people were obviously aware that speed was a desirable characteristic of a good green.

A lot of people think that the quest for speed has come about only recently, but it has always been so. I can remember people talking about fast and slow greens in the '60'S.

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