Air Knifing, AND soil rebuild

[Greenstar]

Do any of you have experience with Air knifing? I have investigated this practice for a few years now through talking to experts in the field, in lectures, and hearing about cases where it was applied, and it appears that it is now the cutting edge in urban tree care, at least here in historic New England. Bartlett Tree Experts and Tree Specialists Inc are all doing it now in circumstances where soils are just no good anymore.
This newer and largely non-invasive practice now is making it possible to keep once troubled trees alive now much much longer than typically their normal life expectancy might initially have suggested. Sometimes for many decades longer.
This is the biggest thing now.
I guess its affordable (for us).
It makes a lot of sense, and I guess is also highly effective.

ANYWAY, that said... I have a few questions if anyone cares to discuss this.
I have a client with a tulip tree with Phytophthera up on a planter bed next to an apartment complex, on the shaded side of the building, in the city here in Cambridge, MA. It looks like a nicely landscaped complex w/ lots of nice fresh mulch probably applied all the time, lush hostas, and such. Probably has good sprinkler systems.
The tree has Phytophthera canker/root rot due to compacted and overly saturated wet soil, as indicated by Bartlett Tree. It makes sense.

REGARDING AIR-KNIFING::
I guess a good one is very affordable at about $650. But my questions are about the whole process because I've still never seen it done.
DOES the process create a huge mess, which may take a while to clean-up around a well maintained landscape? What is the best way to approach, prevent, or deal with this aspect?
Also, can it be as simple as covering soil with e.g. 4" of good quality compost, maybe some lime, and then let her rip!?? How bout some tarps??

OHH, ALSO can a planting mound (too high and deep and compacted, a volcano, around a tree base be air-knifed, and then roots carefully trimmed down, advantitious roots as well, and then grade lowered, composted, etc. and covered with a good composted mulch!?

Anyone do this??
It seems very straightforward to me. To me the hassle seems to be the cleanup and final touches to the yard and planting beds in the form of clean-up and grade. It seems if not implemented well it could turn into a lot of backbreaking labor raking and moving soil, and also cleaning up afterwards.

Thanks,
Ben
(Greenstar/Boston)

 

[beastmaster]

I've wondered about it too. I think it could be useful on trees that have armillaria mellea or related problems, allowing you to expose the roots and allow them to dry out some with out damaging them. The air knife its self isn't that expensive, but don't you need a large compressor to run it? That can cost 50,000 dollars. I am no expert by any means but i know removing a large amount of soil and replacing it with a different soil can create a lot of problems. I think on old established declining trees it might not be the best thing, only causing more stress for them. I wonder if tree services that have an air knife don't maybe create a need so they can add to the bottom line. That being said, I admit i am just a lowly tree trimmer, and would also like to be educated on any benefits of using this tool.

 

[Greenstar]

I remember talking to a guy once who does it. He said first they just spread all the new soil ammendments all over the top of the root zone they are going to add to, and then they use the air knife, walk around, and blast it all in, approximately down to 12"-16" depth I think he says that it can fluff..

Obviously if removing soil, to do root work, and then replacing would create some other obstacles, such as maybe those you are describing, with stress and such..

 

[teamtree]

We have used the air knife many times for many different applications.

We have used it to expose roots around utilities.

We have used it to decompact soil on large construction sites.

We have used it to remove stumps in landscapes or places where grinding may prove difficult.

You can use it to expose roots. This really nice when you have to deal with trees that have been volcano mulched and the roots are growing cirlces around the base of the tree.

You can use it on many different applications outside of tree work as well.

You need a fairly large compressor or it will not be able to keep up.

We usually just rent an air compressor but we have found some compressor fairly cheap but we just don't do enough work to justify the compressor at this point.

As far as the air knife goes, we bought a nice air knife and then one of the guys left it sit on top of the tool boxes on a truck and drove off. $1200 down the drain. We built another one for about $60 in supplies. You have to work with the nozzle a bit to get it right but you can make one. Just have to use a sledge to get the tip narrowed down....lol

 

[treeseer]

OHH, ALSO can a planting mound (too high and deep and compacted, a volcano, around a tree base be air-knifed, and then roots carefully trimmed down, advantitious roots as well,

Yes and sometimes the roots in these mounds are spread out radially and covered.

Most of these other services can also be done by hand, which is less work in tight places.

 

[ATH]

The tree has Phytophthera canker/root rot due to compacted and overly saturated wet soil, as indicated by Bartlett Tree. It makes sense.

Not sure you can "heal" phytophtera with an air knife. You'd have to steralize every last piece of remaining soil and any of teh fungus in the plant itself. I have an AirKnife, and I think it is a great tool, but I think this is beyond reasonable to expect.

REGARDING AIR-KNIFING::
I guess a good one is very affordable at about $650. But my questions are about the whole process because I've still never seen it done.
DOES the process create a huge mess, which may take a while to clean-up around a well maintained landscape? What is the best way to approach, prevent, or deal with this aspect?

The AirKnife probably costs closer to $1200. As has been said, a compressor is the expensive part. I found it just over $100 per day to rent - which didn't leave much room to charge customers a price I think they'd be willing to pay and allow me to make a profit. I bought a used one for (I think I paid) $5500. IngersolRand 185cfm diesel. You probably don't want too much smaller than that.

Regarding the mess - I does make a mess, but it is not really wide spread. You can't blow dry soil (it has to have some moisture in it), so it isn't really dusty.

OHH, ALSO can a planting mound (too high and deep and compacted, a volcano, around a tree base be air-knifed, and then roots carefully trimmed down, advantitious roots as well, and then grade lowered, composted, etc. and covered with a good composted mulch!?

This is where I use it most - a lot of 6"-8" trees that were planted poorly several years ago. As long as the grade is not completely flat and the tree burried too deep, I can usually fix it for less than $200.[/QUOTE]
Anyone do this??

It seems very straightforward to me. To me the hassle seems to be the cleanup and final touches to the yard and planting beds in the form of clean-up and grade. It seems if not implemented well it could turn into a lot of backbreaking labor raking and moving soil, and also cleaning up afterwards.

The nice thing about the AirKnife is that it is better than a leaf blower at clean-up...

 

[Greenstar]

So what kind of psi pressure does the compressor need to generate??
Is this continuous pressure? Does it run continuously while air knifing?

Also, Treeseer, I dont know how easy it would be to introduce a lot of compost well into the root zone by hand.?


Does air-knifing destroy the turf?

 

[Greenstar]

I have a Craftsman 150 max psi 30gallon 6HP-2hp compressor. Its pretty good size.

 

[treeseer]

Also, Treeseer, I dont know how easy it would be to introduce a lot of compost well into the root zone by hand.?

Not easy but not hard, using pick and trowel and garden hose it can be very effective. I've had enough red clay even moist laugh at air tools. Sometimes a pick, or a long pry bar, or some mechanical force is needed for fracturing the soil.

 

[ATH]

Regarding the compressor:

It only uses around 100 psi. Look at the cubic feet per minute. Your shop air compressor is probably 25-30 cfm max. You need a "jack hammer" air compressor putting out at least 150cfm. Mine has a 6 cylinder John Deere engine in it... I think it is 90(ish) HP.

There isn't really a storage tank like a shop compressor (well...there is, but it is pretty small and I think it is there just to be ready the moment when you call for air while the engine revs up). The compressor works by 2 counter-rotating screws pushing air out. So yes--it does run continuously, but revs up to higher rpm when the valve is open.

Finally....you can't really cut through turf too well with the air knife. Because it doesn't cut roots and turf has such a great mat of roots. If you want to de-compact soil under the turf, I suggest one of 2 methods:
1) Kill the turf at least 10 days before AirKnifing
2) Sod cutter to roll the turf away, do the work, then roll the turf back into place if the client wants to keep grass there.

 

[Ed Roland]

Not sure you can "heal" phytophtera with an air knife. You'd have to steralize every last piece of remaining soil and any of teh fungus in the plant itself. I have an AirKnife, and I think it is a great tool, but I think this is beyond reasonable to expect.

Air knife for curative effect? Prb not. yet any treatment for phytophthora should include a soil alteration to discourage conditions that favor fungal populations. A supersonic air tool would be excellent for meeting that goal. Using a fungistat drench buys enough time to make the necessary alterations or perhaps a phosphite injection/soil work is the way to go. Either way you want to increase soil drainage.