"Martin Brown" wrote

Chris Hogg wrote:
Another John wrote:

Having recently created a new border in the grass area, I had a load of
turf to pile up. Finding nowhere else suitable in the garden, I made the
heap under an old cherry tree - I guess it's about 2 or 3 yards from the
trunk. The tree is about 100 years old I'd guess: going on for 2 foot
across the trunk.

A neighbour popped by and said I shouldn't do this: the heap will change
the soil level for the tree's feeding roots (and so will the compost
heap beside it), and ultimately this will kill the tree.

I'd never heard this before. I will move the heaps, but I just wondered
if there's any informed wisdom on the topic in the group.

BTW the neighbour doesn't have any interest in the tree -- he was giving
friendly advice.


I've heard it said that if you heap earth over the roots of an
established tree, the roots will suffocate and the tree will die, or
at least not flourish. I have no idea if it's true, or if it is, what
depth of earth is needed to cause the problem, but it sounds like the
same OWT that your neighbour was repeating.

I have heard it said too although I have never seen a large mature tree
actually killed by small soil level change (ISTR 4" over a wide area is
enough to cause trouble by starving the surface roots of oxygen). Trees can
easily cope with a gradual build up of leaf litter but not a sudden
artificial change in the soil level caused by human intervention.

Compaction in heavily trafficked grassland can also weaken trees in the
likes of Kew gardens where they have taken to experimentally injecting
compressed air into the soil around particularly sensitive specimens.

I am more than a little sceptical of the merits of this but here is the
website of one of the companies involved and their various claims:

http://www.arbornauts.com/terravent.html

(I will concede there might just be an element of truth in it)



It was first noticed at RBG Kew that after the Great Storm of 87 when some
old trees were torn out of the ground and luckily dropped back into the hole
that instead of dying their health and growth improved markedly in the
following years. That gave the Kew scientists the clue they needed that
ground compaction was an important part of tree health.

This is taken from their magazine (years ago).......

K E W ’ S mature trees are under considerable
environmental stress due to factors such as soil
compaction, drought and competition from
grasses. A programme to improve their health
has begun which involves relieving compaction
around the root crown, mulching over
the turf and injecting a mixture of beneficial
mycorrhizal fungi and bacteria (‘MycorTree’,
Plant Health Care Inc.). Loosening of the soil
and injection of the mycorrhizal fungi is being
performed using a ‘Terravent’ Soil
Decompactor, kindly loaned by Terravent UK
Ltd. The success of this root maintenance work
is being monitored, and trees treated in trials
during spring 1998 and 1999 are already
showing improved mycorrhizal systems.


--
Regards. Bob Hobden.
Posted to this Newsgroup from the W of London, UK