Soil compaction

[Rowden the cowboy]

A tree round my way is badly suffering from soil compaction....canopy die back, drought symptoms, water shoots etc....mainly because there are cars parked around it the whole time. Now the parish councils got wise to this and have stopped parking cars all over it but it prompted a question in my mind: what can you actually do to remedy it? I know most people just say to mulch the area for a few years, but do those products such as the air spade or the terravent work? Or anything else for that matter?

[Giles Hill]

You can certainly decompact the ground with an airspade, but you'll need to then protect the ground, if cars are going to park on it again.

 

'Cellular confinement systems' are the most usually specified way of dealing with this. They are basically a gridwork sytem that are available in various thickness - you lay them on the ground and fill them with small loose aggregate to create a porous load-bearing surface.

[AndyElliott]

The terrevent was used by kew gardens to decompact around their trees that were showing signs of stress, followed by mulching underneath the canopies. Last time i heard they had great results with it. The airspades seem to be all the rage at the moment, not sure of the long-term results... they don't decompact so much as remove the top soil, they then usually mulch over the top - i know that again they seem to have good results in the short term, but i would be concerned about the new root growth they stimulate being shallow and very prone to compaction problems again; plus the damaged root tissue (from the spades blast) being open to infection by secondary organisms? just my opinion of course, as i've seen no long term studies either way.

[Lee Winger]

A tree round my way is badly suffering from soil compaction....canopy die back, drought symptoms, water shoots etc....mainly because there are cars parked around it the whole time. Now the parish councils got wise to this and have stopped parking cars all over it but it prompted a question in my mind: what can you actually do to remedy it? I know most people just say to mulch the area for a few years, but do those products such as the air spade or the terravent work? Or anything else for that matter?

 

Air spades aren't suited to this kind of work, they are designed for excavation work, and most Terravents are on there last legs, and damn hard work to use..

 

We have a purpose built machine designed for this kind of work, it works off of a road going compressor, we can de-compact in layers up to 1 m deep, though 500 is usualy more than adequate..

Edited June 3, 2009 by Lee Winger

[Simon Rotheram]

You can certainly decompact the ground with an airspade, but you'll need to then protect the ground, if cars are going to park on it again.

 

'Cellular confinement systems' are the most usually specified way of dealing with this. They are basically a gridwork sytem that are available in various thickness - you lay them on the ground and fill them with small loose aggregate to create a porous load-bearing surface.

 

we fitted some on a driveway...

 

http://arbtalk.co.uk/forum/general-chat/7534-cell-web-tree-root-protection.html

[Giles Hill]

Air spades aren't suited to this kind of work, they are designed for excavation work, and most Terravents are on there last legs, and damn hard work to use..

 

 

Why aren't they suited to that kind of work Lee? I'd been told they were good for this kind of thing, because you can loosen the whole soil profile, whereas a terravent just lifts the ground up in big lumps, which thent fall back in place, filling the gaps up.

 

I've not used either, so it be good to hear from a man who has used both.

[Bundle 2]

There has been something made of the benefits to soil health from the use of airspades....It would be sensible to regard generalisations however with a degree of scrutiny but this must go for terravents also......

Perhaps Lee will expand on the science behind his promotion of the system he uses....?

[Lee Winger]

Why aren't they suited to that kind of work Lee? I'd been told they were good for this kind of thing, because you can loosen the whole soil profile, whereas a terravent just lifts the ground up in big lumps, which thent fall back in place, filling the gaps up.

 

I've not used either, so it be good to hear from a man who has used both.

 

I have the Soil-pick, Air-spade and deep root aerator. The soil-pick and Air-spade are great tools for removing top layers of compacted soil away from tree roots for IE root inspections , root pruning etc etc.

 

IMO they aren't that good at general de-compacting, as you can't remove soil much more than 12'' deep because gravity sends the soil back into your hole, and the only soil vac I've found costs over 20k and the only ones for hire are in the West country and charge a 1k a day..

 

If I could talk people into it i'd go with vertical mulching everytime and general soil de-compaction using the deep root aerator,and let the bugs and worms do the rest, but the trouble is some people don't like the look of mulch so you can't win lol, saying that I did find a client last week , who cared more about the tree than the lawns appearance..

 

Here are a few pics from a recent job

Edited June 3, 2009 by Lee Winger

[Lee Winger]

Perhaps Lee will expand on the science behind his promotion of the system he uses....?

 

Sorry no scientific proof mate, but the trees I and others have aerated seem to have produced some very noticable benefitual changes............

 

Like I said in my last post , radial trenching or vertical mulching is my preferred method, but some wont have it and so out comes the deep root aerator, we can fill the holes up with sand, calcified seawed used to be good , but unfortunatly its not a sustainable commodity......

[Giles Hill]

If I could talk people into it i'd go with vertical mulching everytime and general soil de-compaction using the deep root aerator,and let the bugs and worms do the rest, but the trouble is some people don't like the look of mulch so you can't win lol, saying that I did find a client last week , who cared more about the tree than the lawns appearance..

 

Thanks for explaining that Lee. So... If I've got it right, the airspade will break the soil down more completely, but it's only practical for depths up to 12''.

 

Whereas the deep root aerator works deeper, but creates fissures, rather than breaking the entire soil profile...

 

I think I understand the benefits of vertical mulching compared to the above methods, but see they all might have their place. Do you use some kind of drill or auger to make the holes and if so, how deep do they go?

 

I could imagine that vertical mulching might also be a better option if you were intending to use a cellular confinement system on ground that was already compacted, because it would maintain open channels whilst the surrounding compacted soil would support the weight of the paving. The reason I was pondering this was I've often wondered how effective a load-bearing cellular system is, when it's laid over air-spaded ground - i.e. I was thinking freshly airspaded ground, would potentially have no soil structure and therefore would suffer a certain amount of re-compaction problems from the filled cellular system itself, compared to undisturbed ground. Does that make sense?

Edited June 4, 2009 by Giles Hill