Re: Advice on shredders

Marina & Anthony Green wrote:
> 
> I finally decided to take the plunge and buy myself a shredder, to help me make the best use of the
> mountains of pittosporum leaves and slender branches from my garden for green manure (snip) I have two questions
> 1) how can I work out what sort of green manure will take nitrogen away from my plants ? Have I
> understood the issue properly by thinking that it is the wooden part of shreddings which should be
> used sparingly for this reason?
> 2) do I really need to spend about 500 US dollars to get a decent shredder (i.e. something that will
> shred twigs/branches of up to an inch in diameter?

 Anthony
1) No green manure is going to take away nitrogen from your crops. Any
plant material which is green must have live tissue in it and this is
always high in nitrogen.  In DEAD woody material on the other hand,
nitrogen is in very low supply, if it is there at all, and most of the
material consists of carbon in the form of cellulose and wood.

When a branch on  a tree dies naturally, or an autumn leaf is shed, the
tree always first withdraws an useful materials it can to re-use,
including virtually all the nitrogen.

On the other hand, if you prune off live branches there is no time to do
this, and the greeen parts of the shoots and leaves will still have all
their nitrogen in them. Provided they are shredded within the first few
weeks of cutting they will retain most of this food value.

We regularly shred live prunings from our property and often use them as
instant mulch on garden beds with no precautions. Far from robbing the
ground they act as a good feeding mulch and break down to humus in a
very short time. Even though the shredded material actually contains a
fair amount of the high-carbon wood there is enough nitrogen present for
this not to cause any problems.

The situation where it is possible to get nitrogen robbery is where one
is applying a really high-carbon material, such as wood which was ground
when already completely dead, or sawdust. Even in a live tree the inner
wood which is used for planks is already dead when sawed and the tree
has long withdrawn anything it finds useful. If using such materials a
scattering of N-rich fertilizer or manure on the ground under the mulch
will prevent trouble, but is certainly never necessary with live
materials.

2) Can't help with this one, sorry.

Moira
-- 
Tony & Moira Ryan <theryans@xtra.co.nz>
Wainuiomata, 
New Zealand (astride the "Ring of Fire" in the SW Pacific).
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