Root zone amelioration

[David Humphries]

so, 4 years on from the experiment.

 

Tree is still here, but with a stressed canopy, chlorotic leaves & epicormics running down the branches as it tries to retrench.

 

Also Meripilus giganteus in the root collar.

 

 

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[David Humphries]

so, 4 years on from the experiment.......

 

we did a crude compaction test today with me 1970's state off the art probe (someones still borrowing our IML penetrometer )

 

In the sections where we decompacted with the airspade & added mulch, the probe went in relatively easily to a depth of 45 cms.

 

In the sections where we didn't decompact with the airspade & didn't add mulch, the probe went in (with about the same force applied....honest:biggrin:) to a depth of 20 cms.

 

 

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[David Humphries]

..........In the sections where we decompacted with the airspade & added mulch, the probe went in relatively easily to a depth of 45 cms.

 

In the sections where we didn't decompact with the airspade & didn't add mulch, the probe went in (with about the same force applied....honest:biggrin:) to a depth of 20 cm

 

The first shot from the post above (showing good depth of soil) was taken at No 1 and the second shot (showing compaction) taken at position 2

 

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[Fredward]

Very interesting post, as usual! Can you enlighten me as to the reasons behind not decompacting all of the root plate?

 

Also did you consider the effect that the woodchips may have on nitrogen levels? (even though it had started decomposing)

[David Humphries]

I didn't want to damage fine root hairs/root bark and other beneficial soil flora and fauna across the entire RZ in one hit. (although this was just a hunch at that point)

 

The idea was to make this a two phase mulching operation.

So far we haven't had the opportunity or inclination (if I'm honest) to do the second phase of mulching.

 

 

 

I'm not (and wasn't at the time, based on recollection of conversations with colleagues) convinced that the wood chip mulch depletes nitrogen significantly to be overly concerned about it when weighed against the benefits the mulch would/should give to a situation like this ( I seem to recall I read/heard this from a Glynn Percival paper/seminar presentation type gig)

 

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[Fredward]

That's fair enough, I've always had my doubts when people harp on about woodchip mulch and nitrogen levels, as only a small amount of chip is in contact with the soil, although when it's incorperated into the medium itself there may be more nitrogen depletion, in theory. It all depends on the state of decomposition in the woodchips though, in my understanding anyway.

 

It would be interesting to take samples of the 'ameolirated' soils vs the untouched, to ascertain moisture and nutrient levels. Do you ever perform bulk density tests?

 

So overall would you say the condition of the tree is better now or back then? It's fantastic to see how you are documenting your work and I'm very jealous of the projects that you work on and I'm always impressed by the quality of work produced.

 

Thanks again for posting, it is very interesting for me as I'm working and part time studying a lvl 6 Diploma in Arb, but the practical work I do rarely reflects on, or builds on my classroom work!

[treeseer]

Fred good point about the harping; I just reread Neville Fay's 2005 paper on retrenchment wherein he reviewed decompaction and mulching as standard work, and have seen umpteen projects in the US doing same with great results. Yet all that "intervention" below ground is viewed with suspicion in other places 9 years later, while crown works are shall we say highly intervening to the tree system!

 

There is one shred of data from Chicago where a deep layer of green woodchip had a mild and temporary effect on some shrubs. Other than that, zero, zilch nada.

 

That said I totally agree with the mosaic/gradual approach where any doubt exists. Good luck with level 6; many rungs on the ladder over there!

[Fredward]

Fred good point about the harping; I just reread Neville Fay's 2005 paper on retrenchment wherein he reviewed decompaction and mulching as standard work, and have seen umpteen projects in the US doing same with great results. Yet all that "intervention" below ground is viewed with suspicion in other places 9 years later, while crown works are shall we say highly intervening to the tree system!

 

There is one shred of data from Chicago where a deep layer of green woodchip had a mild and temporary effect on some shrubs. Other than that, zero, zilch nada.

 

That said I totally agree with the mosaic/gradual approach where any doubt exists.

 

Yeah I've noticed some people have a very staunch view on woodchip mulch, I had one nursery owner turn down a free woodchip drop off - he wouldn't use it on his field grown tree because it 'robs nitrogen'. I actully find it quite hard to give away locally.

 

Good luck with level 6; many rungs on the ladder over there!

 

I'm in N.Z and there is a fair bit of studying you can do, I did a level 5 diploma in Hort. at Merrist Wood in the UK, and that was easy compared to what I'm currently working on..

[sean]

Fred good point about the harping; I just reread Neville Fay's 2005 paper on retrenchment wherein he reviewed decompaction and mulching as standard work, and have seen umpteen projects in the US doing same with great results. Yet all that "intervention" below ground is viewed with suspicion in other places 9 years later, while crown works are shall we say highly intervening to the tree system!

 

There is one shred of data from Chicago where a deep layer of green woodchip had a mild and temporary effect on some shrubs. Other than that, zero, zilch nada.

 

That said I totally agree with the mosaic/gradual approach where any doubt exists. Good luck with level 6; many rungs on the ladder over there!

 

Do you know where I can find this paper? Cannot seem to see it on Treeworks publications list on the website.

 

Cheers.

[treeseer]

Do you know where I can find this paper? Cannot seem to see it on Treeworks publications list on the website.

 

Cheers.

 

simply googleable; comon now! page 2

 

http://idox.bathnes.gov.uk/WAM/doc/BackGround%20Papers-135847.pdf?extension=.pdf&id=135847&location=VOLUME1&contentType=application/pdf&pageCount=1

 

All respect to Nev; he did not coin the term but he did advance my understanding when I heard/read him in 2008. I've had occasion to revisit whilst compiling a reference list; worth a reread to let it soak in a little further.