New Air Knife

[appalachianarbo]

I got my new air knife delivered yesterday...I'm excited. I have 3 jobs lined up for it next week, and a large property (~15 trees) lined up in a couple weeks. Some are grid aeration, while some are radial trenching, and one is a soil excavation on a construction site. I'll get some pics and let you know how it goes.

 

[ATH]

Congratulations! Best way to go home dirty. Have you used one before?

Are you renting or did you also buy a compressor?

 

[John Paul Sanborn]

Make sure you have the right filters on your respirator (dust masks DO NOT work)

 

[kennertree]

Make sure the soil is good and moist the night before, it makes it easier to move the dirt around and there is less dust. If you have a water source nearby take a lawn sprinkler out there the night before and let them run a while.

 

[appalachianarbo]

This'll be my first time using one. It's raining out right now, so hopefully the soil will be moist when I do it. I'm renting the compressor. It's $100 a day, so I rent one for a long time fore the same price as buying one. I'll just pass the cost on to the homeowner.

Andy from Air Knife told me that some compressors have a safety mechanism that shuts the compressor down if it senses that the hose is cut or air is bypassing a tool. He said that since the air knife uses a whole lot of air, it may trip the mechanism and shut the compressor down. Anyone run into this? He said that if it happens, you can bypass the mechanism. I'll have to ask the rental guys about this.

 

[treevet]

I've used them before and I'd suggest getting some safety tape and cordon off a pretty good size area. Even if the soil is wet/wetted it is all up in the air and becomes an eye hazard to passers by. That being said, wish I had one and may buy one this winter.

 

[John Paul Sanborn]

Even if the soil is wet/wetted it is all up in the air and becomes an eye hazard to passers by.

Wet is real messy, let it dry to moist/well drained.

Even then there is a lot of drift loss. If you expect to haul some soil off there may be less then you figured, if not then you may need to bring in some replacement.

A very good talk at the TCIA Expo dealt with this, the study was on stressed trees. They found a marked improvement with mulch/fert amendments over straight air excavation.

Since you introduce more free O2 with the soil you accelerate organic loss and soil bulk density.

Fracture the soil, then amend and use the airtool at low pressure to mix the amendments in to 6 inches.

They used 4 large scale same-site studies in across ConUS

 

[ATH]

JPS, do you remember who did the study? I'd like to read up more on what they did and found. Thanks.

 

[John Paul Sanborn]

I'll have to look it up, but she said she was not publishing it till sometime next year.

 

[treevet]

I am sure there is some "dose and timing" involved with this treatment to consider as well. Wouldn't want to further dry out drought stressed roots. Wouldn't want to blow off delicate root hairs or mycorrhizae or worse yet bark. I think it would blow the skin off my arm if left in one spot for a few moments.

The demo's I have seen reveal that damage could be caused IMO. My interest would mainly be to expose girdling roots or decay in major roots. The trenching would have to be done very judicially I would say.

 

[ATH]

I am sure there is some "dose and timing" involved with this treatment to consider as well. Wouldn't want to further dry out drought stressed roots. Wouldn't want to blow off delicate root hairs or mycorrhizae or worse yet bark. I think it would blow the skin off my arm if left in one spot for a few moments.

The demo's I have seen reveal that damage could be caused IMO. My interest would mainly be to expose girdling roots or decay in major roots. The trenching would have to be done very judicially I would say.

Certainly addressing girdling roots is a great use of the airknife. The key here is to address it early enough - which more often than not means blowing into trees that are without symptoms - have to learn what to look for - sometimes as simple as a maple or linden planted too deep...

However, limiting the use to girdling roots is to not recognize the full value of a great tool. Soil improvement is pretty effecient and the air excavation does not tear up the roots to help them (as a trencher would).

As far as drying out roots...as was said above, you need to have good soil moisture or you are wasting time. A little watering to follow-up the treatment and that is not an issue.

Unless you physically hit the roots with the end of the tool, it will not cause root bark damage. You can blow it on your skin (I have) without damage. So with some care, removing the bark shouldn't happen. Probably do need to watch the early early spring to avoid the finest root hairs...

I see what you mean by timing (fine root hairs), but I am curious what you mean "dose"? Radial trenching has been shown to help. If you have the amition and the client has the funds, there is no reason you can't do an entire root system (either decompact the whole area, or do soil replacement if you really want to get involved). Certainly this would be more beneficial than radial trenching, but the question is "how much better - and is that improvement worth the extra cost?".

 

[treevet]

Certainly addressing girdling roots is a great use of the airknife. The key here is to address it early enough - which more often than not means blowing into trees that are without symptoms - have to learn what to look for - sometimes as simple as a maple or linden planted too deep...

However, limiting the use to girdling roots is to not recognize the full value of a great tool. Soil improvement is pretty effecient and the air excavation does not tear up the roots to help them (as a trencher would).

As far as drying out roots...as was said above, you need to have good soil moisture or you are wasting time. A little watering to follow-up the treatment and that is not an issue.

Unless you physically hit the roots with the end of the tool, it will not cause root bark damage. You can blow it on your skin (I have) without damage. So with some care, removing the bark shouldn't happen. Probably do need to watch the early early spring to avoid the finest root hairs...

I see what you mean by timing (fine root hairs), but I am curious what you mean "dose"? Radial trenching has been shown to help. If you have the amition and the client has the funds, there is no reason you can't do an entire root system (either decompact the whole area, or do soil replacement if you really want to get involved). Certainly this would be more beneficial than radial trenching, but the question is "how much better - and is that improvement worth the extra cost?".

Not sure I agree with "blowing into" tree without symptoms. A tree planted too deep would have a symptom...no flare at the buttress.

To say the air excavation does not tear up the roots like a trencher is like saying dropping a bowling bowl on your foot is ok compared to driving over it with a Mack truck. The dose in this may be to not hold the tip too long on a root. Timing might also include such as watching for a heavy dose right as leaves are forming. This is when new xylem is forming and is not lignified and is quite delicate. Bark might be torn off at this time. Dose might also need to be more carefully dispensed when trees are drought stressed IMO. Timing might be better in the spring than in the heat of the mid summer. Just putting up some thoughts for consideration. The 6 or so times I have seen this tool demo'ed, I left thinking that it "would" indeed blow the skin off my body if more than a glancing blow occurred.

There is no question that this is the best way to alter and improve the soil quality in high volume in the root zone by trenching. A guy around here used to back his stump grinder to the trunk all around the tree and bury the cutter head in the ground and drive outward. He called this ray aeriating and actually charged clients for this massive damage to their trees.

 

[John Paul Sanborn]

I am sure there is some "dose and timing" involved with this treatment to consider as well. Wouldn't want to further dry out drought stressed roots. Wouldn't want to blow off delicate root hairs or mycorrhizae or worse yet bark. I think it would blow the skin off my arm if left in one spot for a few moments.

The studies does was .5ft for every inch DBH, they did not discuss timing, but the trees were all stressed from compaction, poor soil and drought strees.

First year there was some indication of fine root loss, but there was a marked improve in the airstool, fert, compost trees across the board compared to those where only one component was used and the controls that were left behind.

I cannot remember both species, but i'm pretty sure one was S. rubrum.

I would go farther, but have to get the dogs put away to leave for a dental appointment...

 

[ATH]

.......Timing might be better in the spring than in the heat of the mid summer. Just putting up some thoughts for consideration. The 6 or so times I have seen this tool demo'ed, I left thinking that it "would" indeed blow the skin off my body if more than a glancing blow occurred........

2 points from experience:
1) You don't want to try to blow dry soil - even if it did not have any impact on drought stressed trees. I am not saying it doesn't have impact as it probably would (haven't tried it, haven't seen anybody else testing it). Dry soil just doesn't work well (especially the heavy clays of NW Ohio). So...yes you are absolutely correct that you don't want to use air excavation during the heat of the summer.

2) It will not damage unpierced skin (or undamaged bark). I would have no problem blowing it on unborken skin. However, if you blew it into a cut, it would separate skin from underlying tissue and probably make the cut much larger pretty quick. OUCH! Same goes with the roots. I have not seen bark being blown off unless it was physically damaged by something other than air (like accitentally bumping the roots with the tip of my Airknife). During the early spring, that bark is more likely to be knocked off by a gentle bump and more will get blown off once it is damaged; as opposed to fall when you have to hit it pretty good to knock a chunk off. So again, I agree - extra caution has to be exercised during the early spring, but I don't think you need to avoid using it then.

 

[ATH]

The studies does was .5ft for every inch DBH, they did not discuss timing, but the trees were all stressed from compaction, poor soil and drought strees.

First year there was some indication of fine root loss, but there was a marked improve in the airstool, fert, compost trees across the board compared to those where only one component was used and the controls that were left behind.

I cannot remember both species, but i'm pretty sure one was S. rubrum.

I would go farther, but have to get the dogs put away to leave for a dental appointment...

Not surprising that replacing crappy soil with good soil is more beneficial than just adding one component (pore space) to the crappy soil... But it is important to get those things documented by good research so we know the best way to behave in the field!

When you said the 5.ft per inch of dbh, does that .5ft indicate length of trench per trench? Do you remember how many trenches they did? I have been doing 5 on the smaller trees and 8-10 on the larger trees... Just curious if they considered anything "standard"?

 

[Ed Roland]

Check out some of Dr. Smiley's work.

http://www.patentstorm.us/patents/6845587/claims.html

 

[John Paul Sanborn]

When you said the 5.ft per inch of dbh, does that .5ft indicate length of trench per trench? Do you remember how many trenches they did? I have been doing 5 on the smaller trees and 8-10 on the larger trees... Just curious if they considered anything "standard"?

This was total replacement diameter, sol a 12 inch tree would have a 6 ft radius excavation 6 in down.

Other uptake studies have show that this is the area of greatest fine root density. There is more farther out, but it more diffuse. For the same reason Cambistat and Merit will work just as well with a basal drench as with a wide grid pattern (the benefit of the latter is stimulation of fine roots out past the dripline) so you get the most bang for the buck with the least disruption of the landscape.

The drawback is that many people dislike large rings for large trees ( I try to encourage perennial beds in these cases, especially deep rooting prairie varieties, such as coneflower and black/browneye susan with the ubiquitous hastas) in these cases trenching/ reseed is the best alternative. I know bigger companies that use a sodcutter, roll it up and then replace the sod after treatment.

 

[appalachianarbo]

I used the air knife on 3 jobs last week. It was a cold morning, so there was a 3" frozen layer on top. Luckily, the first job was in the woods, and there was a layer of leaf litter over much of the surface that kept the soil underneath from freezing. I excavated about 2' of soil from around the trunk of a 20" hickory. You can see the old soil line in pic #2.

It was warmer out by the time I got to the second job - aeration of a codominant hemlock. The holes were ~ 2" deep. I backfilled with coarse vermiculite. Took about 30 minutes total for ~ 50 holes.

 

[appalachianarbo]

The third job was another codominant hemlock, 60" DBH. Very compacted, so I trenched and did some hole aeration. The trenches were 8-10" deep, although they look shallow in the pics. Backfilled with vermiculite, covered with soil, and the root zone will be mulched by the homeowner soon.

 

[John Paul Sanborn]

Why use just vermiculite vs. a loamy mix?