root collar excavation?

[treeman82]

I had done some charity work on a weeping cherry a week or two ago. Tree is about 8.5" in caliper. I had vertical mulched and fertilized with M-Roots. I pruned out the major dead wood. I also did some root collar excavation because the tree was a telephone pole. Apparently it was burried about 6 - 8" too deep. I pulled back the soil about 1 foot away from the trunk on all sides. However, I couldn't keep that distance as I went lower in the hole because of roots which were turning up. So the hole and tree looks somewhat like this \|/ I purchased some crushed marble chips and filled them into the hole around the trunk. How bad did I screw up?

 

[Matt Follett]

I wouldn't use screw up.

I think you are on the right track, the only problem I see is the potential for water to accumulate in the 'hole' around the trunk, what is the soil porosity like? ie will it drain adaquetly? Remember from your soils classes about translocation of water through soils of different porosities and the difficulty it has moving from an area of high pore space to low (your marble chips will provide high pore space). This is why we don't fill planting holes with gravel...

But given that we are only talking 6-8 inches over a 2 foot diameter hole, and providing the soil is not hard baked clay... you should be okay, if it is hard baked you could try forming french drain type canals (trenches filled with porous material such as gravel or your chips) away form the base of the tree (like your radial trenching) to provide the water with a path to absorbtion

Just my two cents

 

[treeman82]

Matt, I do remember about the difference in porosities in soils, and I remeber that this is the opposite of how it should be. The soil below where I placed the chips is rather hard. I would have loved to have gone lower, and angled the hole to the outside, but I couldn't do so because of the presence of some good sized roots. I figured that by putting the marble chips there, I would have let some air get to the root collar, and also have kept the bark from getting too wet. It was obvious to me that the bark has been pretty moist for a while now.

That being said, what would you guys suggest?

 

[John Paul Sanborn]

Sometimes you gotta do what you can. With the airspade i would have tried to modify the root system, maybe prune maybe straighten.

What you have in effect done is make a tree well

Maybe do a perc test near by to check drainage, or use the hole you have.

Hydrological discontinuity - Water movement is a surface effect and capilary (or capilarity is an aspect of surface effect)


deffinition of capillarity

When there are distinct horizons then the movement of water from particle to particle (ped to ped) cannot occur and each horizon must saturate before downward movement can occure.

in changing grade, we can effect this by disturbing the boundry between the horizons. When useing a gravel, mix some sand in with the native soil, add a shallow layer of gravel, then mix sand with it then add the rest of the gravel.

 

[treeman82]

John, as I was doing the work, I kept saying to myself "????, that JPS should be out here with that air spade of his. This would be so much easier." Too bad it doesn't pay for you to come out for 1 small charity tree.

 

[Kneejerk Bombas]

We built an air powered soil mover tool for literally $20 worth of plumbing supplies. Rent an air compressor for another $80, and you're good to go.
I agree with Matt that you could have dished it out more. Another trick is to use light weight lava rock to back fill. Leaving the hole empty might be the best.
If you have large roots near the trunk, maybe they need to be removed anyway.

 

[treeman82]

Mike, thank you for the lava rock idea. I would have never thought about that. I wound up just putting a couple bags of the marble chips down. Actually 200 lbs worth in this one hole.

 

[John Paul Sanborn]

The large bark much works well too, that bagged stuff that has 1-2 inch chunks.