August 22, 2012

High Tech Water Management

For those of you that may have been regularly following my blog this summer, you can probably recall a couple of posts highlighting the importance of water management on the golf course.  For us, water management is the integration of two components with one basic concept.  The components involved in water management are of course the irrigation/water delivery system, and the soil in which we are irrigating.  The concept is that we don't water to over water the turfgrass, and we don't want to underwater the turfgrass.  Just the right amount is critical.

A new tool arrived on the market in the last few years that marries these concepts into hard numbers and science, compared with old-fashion guesswork and feel.  Digital moisture meters, based on the concept of time-domain reflectometery, give superintendents the ability to put a probe into the ground, push a button, and instantly get a reading of the exact volumetric percentage of water in the rootzone.  The old standby method of checking soil moisture involved pulling a plug from the ground with a profiler and looking, feeling, smelling, tasting, and listening to the soil to try and "guess" how much water was actually in it.

I purchased one of these moisture meters last week, and am still learning the intricacies of exactly how to utilize it.  Every green responds to different levels of moisture differently.  Some greens have a much deeper sand layer than others, some are composed of different types of sand, almost all of them have different amounts of organic matter in that sand, and the turfgrass root structure capable of utilizing the water is different on almost every green.  While one water volume might be healthy on one green, on another green that same number might mean turf that is already way past the wilt point. 

The main goal with this instrument is to take the guess work out of determining how much moisture is in the rootzone.  We can pinpoint an exact mositure level a green is at, and determine if it might need only handwatered in a few spots, the overheads run on the entire thing, or if it has adequate moisture everywhere and doesn't need any water at all.  This will be especially helpful during the hot and humid period in the summer when we need to keep the greens moist, but not too wet to avoid suffocating the grass and increasing our disease potential.

Another area the moisture meter will be helpful with is producing uniform and consistent moisture levels across each individual green.  As everyone is probably aware, our irrigation system is horribly outdated, which means:  heads are improperly spaced, piping is too small, pressure is too low, and any sort of detailed control is impossible based on the 30 year old wiring.  What this leads to is greens that lack any sort of uniform moisture distribution.  The three following examples are all taken off of the same green, number 5:

From the back right of 5 green, with only 9% moisture this area was already showing slight signs of drought stress.
Also, this portion of the green is so firm that I think if you landed a PW here your ball would probably bounce
like it had just landed on a concrete cartpath.

From the front left of 5 green, 17.4% moisture seems to be a pretty comfortable moisture level for us.  This area of
the green will receive balls well, but should still provide a firm and smooth surface to putt on.

From the very middle of 5 green.  This area is where all the water from the irrigation heads on the perimeter of the green
land because they don't have enough pressure to throw back out to the perimeter on the other side.  At 30% moisture,
this area of the green is like a sponge, if you landed a PW here the ball might plug in its own ballmark. 

With such an outdated and inaccurate irrigation system, the only way to try and get any sort of uniformity in the moisture in the greens is by handwatering the dry areas with a hose, and allowing the remainder of the green to dry out.  You might notice in all of the above pictures, I took a soil profile with an old probe from each area to show how difficult it would be to determine with any accuracy how much moisture was there.  This meter gives us specific numbers in order to know in advance how to plan our watering of each individual green.

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