Need some help with airspade proposal

802climber

Active Member
I am quoting some airspade work on a large sugar maple. The tree is 33" DBH and has a 100 foot crown span (dripline to dripline). About half of this area is going to be vertical mulched (gas drill, 3' grid) to reduce impact to turfgrass and landscape plantings. The other half is undeveloped and going to be de-compacted with an airspade. I would like to do some radial trenching, and curious how deep and how far out from the stem I should go? I am thinking of speccing 12-18 inches deep for decompaction and 24 inches deep for radial trenches, then tilling in the amendments w/ airspade.

We are starting with an RCX (to look at SGR and rot) and will then radial trench out farther in the undeveloped area and not as far in the lawn/landscape area. For amendments I am thinking of some pea gravel and perlite. It is a very dry and compacted urban site. Also some K-Mag and wollastonite and biostimulant w/ myco (diehard root reviver). See attached pic of soil test results.

This project will be billed hourly due to the many variables involved, but I would still like to give my client an idea. My thought is 1-1.5 days. Would anyone care to venture a guess as to how long it will take a 2-man crew to perform the soil work listed above? The area needs to be york raked beforehand and we will install a 4 inch layer of composted mulch when we are done. We will drench the area several days prior, and there is no turf removal required. Any time estimates for the airspade work and vertical mulching would be much appreciated. Do not count prep time, mulch installation, or any potential time spent root pruning, dealing with angry neighbors etc.

Thanks for reading!


soil.jpg
 

JD3000

Most well-known member
Location
Columbus
If you rent or borrow a sod cutter, you will be able to radial trench out into the turf area. Just dont keep the sod rolled up for too long and settle the back fill well to account for the settling.
Trenches work significantly better due to the volume of soil improved. Do the math...figure volume for all your vertical bores compared to one single trench, trench wins easily. This work is much more time consuming but ultimately more effective. You can always do some vertical coring between trenches too.

I generally backfill trenches with native soil mixed with compost or another organic ammendment and perhaps others based on what Im trying to accomplish. In my area, I generally deal with heavy poor draining alkaline clay so my ammendments would help to improve structure, aeration/drainage, bio-diversity and micronutrient availability (hopefully).
In your case, acidity and base nutrients are more problematic as well as compaction. Perhaps ammendments that are a bit more alkaline would be appropriate? Looks like Kmag could be a good choice based on your test results but also consider a dolomitic lime product to incorporate and probably top dress with.
Mycorrhizae cant hurt in all likelyhood but it will add to your product costs. I've generally moved away from them in favor of using composts, forest top soil, humate products, and occasionally non aerated compost tea.
Do you own a compressor or renting? Figure that cost and travel too.
Time consuming and dirty work I know, but 1 to 2 days sounds about right but the length of the trenches and back filling time can be hard to estimate. Depends on how compacted the soil is so soaking ahead of time is a good idea.
 

DSMc

Well-Known Member
Location
Montana
This is Sylvia. The "S" in DSMc.

This is a very aggressive proposal. May I ask how you determined the amount of compaction, and what is the overall condition of the tree? I couldn't tell by how you worded the RCX, but can you see the SGR and rot already?

Also, why did you select Willastonite as a calcium amendment? With that low of pH and that high of Al, I would look into toxicity issues. There is a nice amount of organic matter, which is probably where the high P is from. But the downside with high P levels, is mycor won't make the association with the plant as well as the possibility of the P outright damaging or killing the mycor. What are the soils in this area? I am assuming Ultisols but have you run a survey?

You mentioned it is a dry site (as well as the compaction), what is their watering regimen?
 

JD3000

Most well-known member
Location
Columbus
Right right. What's the bulk density and how did the compaction happen? Recent construction? How deep does the compaction go?

A foliar nutrient test will help show you how the tree is reacting to the soil chemistry but also consider root loss and root dysfunction if the tree was damaged during construction.
 

JD3000

Most well-known member
Location
Columbus
An interesting alternative, and upsell, would be to incorporate the tree into a much larger bed and then plant some native understory woodies and perennials. I would think small, qt perennials and small shrubs that would tolerate the site's soil. Planting would go very quickly after air spade stirring and incorporating whatever products and ammendments you decide to use. Follow with mulch of your choice. Small plants fill in very quickly if appropriately chosen. It would look a bit sparse at first but they'll grow! This could also improve for soil biodiversity/myccorhizae associations and their roots will help with soil compaction eventually. Will require some spot watering for the first season but it would be an aesthetic and soil related improvement over turf.

Food for thought.
 

802climber

Active Member
DSMc said:
This is a very aggressive proposal. May I ask how you determined the amount of compaction, and what is the overall condition of the tree? I couldn't tell by how you worded the RCX, but can you see the SGR and rot already?
Sure. This is a dying tree and my reaction is certainly above and beyond my average proposal for preventative maintenance. It is an unpleasant suburban type site with just about every possible environmental stressor killing the tree except road salt. The owners have put a lot of money into their lawn and landscape and through the years the tree has been treated like a piece of furniture rather than a living plant. What this old tree really needs is a permanent TPZ out past the dripline. I have not measured the amount of compaction, but I will say that I had trouble even getting core samples for the soil test.

On one half of the root zone there is a shed, retaining wall, and dump site for LOTS of leaves, yard waste and compost. Let's call it "the bad side". I was called out to take a quick look at the tree a few years ago, (when it still had a full crown) and stated that it had moderate tip dieback and looked stressed, but my proposal to further investigate was declined in favor of a large nearby tree removal project which I did not even put in a bid for. 20+ large white pines were removed using "the bad side" as the only access for extracting the material. There are now fresh pine chips everywhere. I am not sure of the extent of the compaction and root damage but apparently it was a big muddy mess.

We were finally hired last fall, but just to deadwood the tree. It had light to moderate deadwood. They called me back early this summer to say that the canopy was suddenly almost 50% dead/dying. The foliage on "the bad side" was scorched, stunted, and/or already gone by the time they called me. We sent lots of foliar samples, and the lab said they did not have foliar disease or enough pest presence to warrant treatment. We sent wood samples for Verticillium Wilt and they came back negative. We are in year two of a drought and had a very abnormal winter last year. Fluctuating temps and no snow. I suspect freezing injury to the roots of this and some other dying trees I have been looking at, due to sudden extreme cold with no snow cover. My septic line froze. My septic guy's septic line froze twice.

Our next step is to move the shed, do a RCX, and probably proceed with the soil work I mentioned in my original post. It is obvious without excavating that girdling roots and crown/root rot are present in some capacity. I think it makes sense to wait until next spring (or longer?) and see if there is any refoliation or further dieback. At that time we would decide whether to consider removal or proceed with more costly management options including a watering regimen, testing/treatment for phytophthora (highly suspected), potentially Cambistat, etc...
In the meantime I want to prescribe some aggressive measures to revive the ailing root system. It might be too little too late but we would like to give the tree a chance.
DSMc said:
Also, why did you select Willastonite as a calcium amendment? With that low of pH and that high of Al, I would look into toxicity issues. There is a nice amount of organic matter, which is probably where the high P is from. But the downside with high P levels, is mycor won't make the association with the plant as well as the possibility of the P outright damaging or killing the mycor. What are the soils in this area? I am assuming Ultisols but have you run a survey?
Is there another calcium amendment that would be better? I have read a lot about the wollastonite (calicum silicate) application at Hubbard Brook in NH. The goal was to mitigate soil acidification from acid rain which led to a declining sugar maple population, very low Ca and very high Al. They actually had the wollastonite pelletized for slow release and apparently, decades later it is said to have been quite effective in improving health & vigor of the sugar maples among other species.

DSMc said:
You mentioned it is a dry site (as well as the compaction), what is their watering regimen?
The site has been on a regimen of lawn fertilizers, herbicides and apparently liquid bleach near the roots of the dying side of the tree (to kill a rodent???), enough insecticides to kill a horse, etc etc for several years. I think they have become apathetic about the whole thing because not even the lawn has been watered this season. They have had trouble maintaining a nice lawn but I have not seen any records of soil testing, amendments or any type of aeration being done, just a list of about a dozen different chemicals being applied.
 

802climber

Active Member
An interesting alternative, and upsell, would be to incorporate the tree into a much larger bed and then plant some native understory woodies and perennials. I would think small, qt perennials and small shrubs that would tolerate the site's soil. Planting would go very quickly after air spade stirring and incorporating whatever products and ammendments you decide to use. Follow with mulch of your choice. Small plants fill in very quickly if appropriately chosen. It would look a bit sparse at first but they'll grow! This could also improve for soil biodiversity/myccorhizae associations and their roots will help with soil compaction eventually. Will require some spot watering for the first season but it would be an aesthetic and soil related improvement over turf.

Food for thought.
All good points. We are definitely billing for the whole thing. It is just the work with the airspade and drill that I needed help speccing and estimating. I am thinking 1-2 days sounds good for the soil element, but we will easily burn up 3+ days with the whole thing. It is going to get cost prohibitive pretty quick here. Moving shed, york raking to drip line/disposing of debris, soil work, mulch........I can rent a 185 CFM compressor and will factor that in along with everything else.

Do my depths that I mentioned seem like reasonable targets for the airspade work? As far as length of the trenches, is it common to go out to the dripline or what? I guess what I am getting at is, is it better to do a greater amount of short trenches, or fewer quantity of lonnggg trenches?
 
Last edited:

JD3000

Most well-known member
Location
Columbus
Ugh. Rough work I know. Got a similar project comming up to save some sycamores. Situation where tree retention rather than tree conservation during home construction happened.
The folks involved were interested in large bed expansion and understory planting so we'll see how it goes.

What does that willaCa do in the soil? What reactions occur with time? Soil test showed low Mg and Ca with low pH so I first thought a dolomitic lime was appropriate.

Dr Smith has published on acid deposition and how it relates to Ca, Mg, and Al so check it out.
 

JD3000

Most well-known member
Location
Columbus
More shorter trenches would likely improve a greater volume of root zone but run the math for both. Really depends on the sq ft that have been compacted and where and how much root loss occurred.
 

802climber

Active Member
Ugh. Rough work I know. Got a similar project comming up to save some sycamores. Situation where tree retention rather than tree conservation during home construction happened.
The folks involved were interested in large bed expansion and understory planting so we'll see how it goes.

What does that willaCa do in the soil? What reactions occur with time? Soil test showed low Mg and Ca with low pH so I first thought a dolomitic lime was appropriate.

Dr Smith has published on acid deposition and how it relates to Ca, Mg, and Al so check it out.
I will do that, thanks. I have thought about reaching out to someone at HBEF and asking why they went to such great lengths to use wollastonite in particular. However, I have such a limited grasp of soil science that I would probably just embarrass myself.


Sent from my iPhone using Tapatalk
 

JD3000

Most well-known member
Location
Columbus
GTS man GTS.
I thought dolomitic because its alkaline and provides Mg and Ca.

I might add that you might want to take a step back and really think about whether this tree is salvageable. Saw the bit about a retention wall, does the tree also pre date any grade changes? You've described quite a bit of dieback so I got me wondering
 

mrtree

Well-Known Member
About half of this area is going to be vertical mulched (gas drill, 3' grid) to reduce impact to turfgrass and landscape plantings.

You can much more quickly and easily vertical mulch using the air spade.

The other half is undeveloped and going to be de-compacted with an airspade. I would like to do some radial trenching, and curious how deep and how far out from the stem I should go? I am thinking of speccing 12-18 inches deep for decompaction and 24 inches deep for radial trenches, then tilling in the amendments w/ airspade.

An idea of what the soil texture is will help to understand the situation.

You need to do some bulk density testing before making a prescription. It seems unlikely that you have compaction two feet deep. Compaction is easily shown to occur near the surface, generally not very deep. The compaction is related to soil type, soil moisture (when compacted) and bearing weight and frequency.

While something such as a Dickey-Moore Penetrometer can show you compaction variation across your landscape it can note tell you density. You need something such as this: http://www.soilmoisture.com/SOIL-CORE-SAMPLER-2-1-4-IN.-DIAMETER/ to be able to determine density.


This project will be billed hourly due to the many variables involved, but I would still like to give my client an idea. My thought is 1-1.5 days. Would anyone care to venture a guess as to how long it will take a 2-man crew to perform the soil work listed above?

There is no way you can air spade to 24 inches in that time, 6 inches yes, not 2 feet. As you increase depth time will increase exponentially as you need to move soil in layers to reach deeper. An airspade is pretty useless at moving large volumes of soil from depth much beyond 8 inches.
 

ROYCE

Well-Known Member
Location
Vermont
"There is no way you can air spade to 24 inches in that time, 6 inches yes, not 2 feet. As you increase depth time will increase exponentially as you need to move soil in layers to reach deeper. An airspade is pretty useless at moving large volumes of soil from depth much beyond 8 inches".

Super Sonic Air Knife? That is very effective at getting deeper than 8". Not sure about 2 feet. But there powerful.
 

DSMc

Well-Known Member
Location
Montana
Wow. that is some serious tree abuse, 802. It is always frustrating to be called in when the outcome is so poor. I asked about Willastonite because I have never used it so was curious. We rarely (almost never) have acidic soils to deal with, so liming is not generally considered.

Go ahead and contact the HBEF. At least go on their website, they have some very helpful/informative articles re this. It is also good to note these amendments were successful without incorporation into the soil.

The apparent popularity of using the air spade is a bit of a concern to me as it pulverizes the soil and destroys aggregation. So it is good to be sure it is being proposed in critical situations, not as a routine maintenance.

Sylvia
 

DSMc

Well-Known Member
Location
Montana
An interesting alternative, and upsell, would be to incorporate the tree into a much larger bed and then plant some native understory woodies and perennials. I would think small, qt perennials and small shrubs that would tolerate the site's soil..... Follow with mulch of your choice. Small plants fill in very quickly if appropriately chosen. It would look a bit sparse at first but they'll grow! This could also improve for soil biodiversity/myccorhizae associations and their roots will help with soil compaction eventually. Will require some spot watering for the first season but it would be an aesthetic and soil related improvement over turf.

Food for thought.
The planting of compatible species in a mulched area is excellent advice for most situations. Selecting plants specifically with deep rooting capability helps mine the soil, bringing up nutrients to be released back. The incorporation of living roots if used in conjunction with an organic litter layer (mulch) will decompact the soil faster than mulch alone.

Sylvia
 

JD3000

Most well-known member
Location
Columbus
Indeed S. Read a bit about no till farming recently for my own veggie garden. Very interesting stuff regarding compaction, OM, organisms, glomulin (spelling?) etc
 

JD3000

Most well-known member
Location
Columbus
The planting of compatible species in a mulched area is excellent advice for most situations. Selecting plants specifically with deep rooting capability helps mine the soil, bringing up nutrients to be released back. The incorporation of living roots if used in conjunction with an organic litter layer (mulch) will decompact the soil faster than mulch alone.

Sylvia
And a well planned and executed landscape design looks way better than a big empty mulch area!
 

mrtree

Well-Known Member
You cannot blow soil from much depth without high volume and pressure, high enough that you are stripping roots and doing more damage.
 

802climber

Active Member
About half of this area is going to be vertical mulched (gas drill, 3' grid) to reduce impact to turfgrass and landscape plantings.

You can much more quickly and easily vertical mulch using the air spade.

The other half is undeveloped and going to be de-compacted with an airspade. I would like to do some radial trenching, and curious how deep and how far out from the stem I should go? I am thinking of speccing 12-18 inches deep for decompaction and 24 inches deep for radial trenches, then tilling in the amendments w/ airspade.

An idea of what the soil texture is will help to understand the situation.

You need to do some bulk density testing before making a prescription. It seems unlikely that you have compaction two feet deep. Compaction is easily shown to occur near the surface, generally not very deep. The compaction is related to soil type, soil moisture (when compacted) and bearing weight and frequency.

While something such as a Dickey-Moore Penetrometer can show you compaction variation across your landscape it can note tell you density. You need something such as this: http://www.soilmoisture.com/SOIL-CORE-SAMPLER-2-1-4-IN.-DIAMETER/ to be able to determine density.


This project will be billed hourly due to the many variables involved, but I would still like to give my client an idea. My thought is 1-1.5 days. Would anyone care to venture a guess as to how long it will take a 2-man crew to perform the soil work listed above?

There is no way you can air spade to 24 inches in that time, 6 inches yes, not 2 feet. As you increase depth time will increase exponentially as you need to move soil in layers to reach deeper. An airspade is pretty useless at moving large volumes of soil from depth much beyond 8 inches.
Thanks that is some good info. And a good point about moving soil. We will not have the resources for much of that on this job. So perhaps I will spec a depth 6-8" OR LESS for the decompaction, and go a little deeper for the trenches. Don't have any more budget for more diagnostic work on this one until they see some "action". I am, however, adding all of this to my toolbox so I can do a better job initially on future trees. These people want to see us out there making some noise stat. Something will be a whole lot better than nothing. You don't think that vertical mulching with the airspade will crap up their lawn and plantings way worse than an auger bit?
 

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