[Joel_Stewart]

I'm a novice, not in the golf business but am trying to learn.  

With that said, I played NGLA two weeks ago, just 2 days after they had aerated the greens.  They used what I understand was a hydrojet system, forcing water into the ground creating holes and then filling them with sand.  The greens putted almost perfect thus my question for you green committee and supers, why do some courses use hydrojet and others the standard core aerators?  Which is best?

[RDecker]

Joel,
I'll try to answer your question a little bit anyway.  Hydrojecting and traditional Core cultivation are both valuable cultural practices used by Superintendents to help relieve compaction and remove thatch build up on greens as well as other playing surfaces.  Core cultivation or traditional aeration (same thing) is still the best way to reduce compaction and also allows the super the ability to amend the soil profile with topdressing or other soil amendments if they chose.  The downside to this practice is that it takes a green on average about 2-3 weeks to heal fully from aeration.  Hydrojecting on the other hand is more of a quick fix type of procedure, sometimes you can lightly topdress afterward but usually the holes are too small to get alot of material down in.  The upside of hydroject though is that the green is playable immediately after and usually nobody can even tell it was done.  Ideally the Super will use a combination of these two in addition to deeptine aeration, verticutting and light topdressings to maintain and manage the greens.

[PGertner]

Just one super's opinion:

The hydroject is a nice tool and the small channels created in the soil are very beneficial for your green's turf.  However, the hydroject should NOT be used as a substitute for core cultivation, which is the most important procedure your Super can do to help the greens.  

[Steve Okula]

I agree with PGert.

The hydrojet should be used only as a supplement to routine hollow tine aeration. the hydrojet is particulary useful on greens of heavy soil, under heavy play, and in hot weather.

To clarify some terms as I see them used in the business:

Hollow tine aeration, or coring, uses hollow tubes to remove plugs of soil 2-4 inches deep from the turf. It can effectively reduce thatch, as it physically pulls out the thatch on top of the plug. It is far and away the best method to reduce compaction. The holes are usually back-filled with sand or whatever amendment best suits the situation. Most courses hollow tine greens twice a year. The disadvantages are the cost of collecting the plugs and a 2-3 week disruption in the playing surface. Tines can vary in diameter from 1/8 to 3/4 inch. The larger diameters are more beneficial to the turf in the long run but need longer to heal over.

Solid tine aeration punches holes in the turf without actually removing any material. It does not reduce thatch, and the affects on compaction are limited. It is quicker and less expensive than hollow tining, and has much less affect on the playing surface. Solid tine are about the same size and diameter as hollow tines.

The hydrojet uses high-pressure nozzles to create holes in the soil surface. It does not reduce thatch, but neither does it disrupt the playing surface.

Deep tine aeration, is an aeration with tines from 4-15 inches deep. It can be done with either hollow or solid tines. It provides the best long term relief for compaction, but it naturally causes the greatest disruption to the surface and is the most expensive to perform.

[Guest]

Any of the superintendents here have experience with “drill & fill”?  From what I gather the aeration holes are up 16 inches deep.  Once the “drill” is complete, the holes are usually filled with sand.  This is an expensive project – is it worth the money?

[Don_Mahaffey]

Guest,
Drill and fill is expensive as it takes a lot of labor and a kiln dried sand that can run up to 3 times the cost of regular top dressing sand. Here's my take on drill and fill. If you have non-permeable layers that the drill will penetrate, then this method has merit. If, however, you have pushed up greens with a fairly uniform soil texture, then all you're doing is punching deep holes and filling with sand, but you are not improving drainage. Think of a 6 inch piece of concrete. Drill an 8 inch hole and you create a channel to the soil under the concrete which may drain better then concrete. Now, if that concrete is 2 feet thick and you drill a 18 inch hole in it, have you improved drainage? Short term maybe, but not for long. If you are trying to improve drainage, drill and fill may work if you are penetrating to a faster draining soil. If not, other methods can be used to move water through the green.

[ian]

Is this the drill and fill your refering to. If so I thought pictures would be helpful.







For fun I posted this old photo. What is this? It can't be a mower can it?

[Rich Goodale (Guest)]

Ian

I think it is a primitive fertilizing system, known in some cirlcles as a horse's ass.

[ian]

I have also been called a primative fertilizer system.

[Chris Collins]

The aerator in question while somewhat similar to a Hydrojet is called a DryJect, for its ability to inject dry sand and topdressing into the root zone. The DryJect has a distinct venturi feature which is very efficient. At NGLA over 30 tons of sand was injected into the greens in approximately 9 hours.
The venturi effect forces material through the rootzone with
vertical and lateral movement and very little waste.  
Agronomically the DryJect can do many things above and beyond hydrojeting and coring while still providing excellent putting surfaces afterwards.

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