I shredded a large part of a big Leylandi a few years ago using a
big hired shredder ...

http://tinyurl.com/iumu

(http://www.hss.com/Fae.asp?syspage=w...2814&Division=
HIRE&Category=GARGARDEN&sysclearSQL=YES)

and very good it was too. Worked by grinding stuff up with a
toothed wheel working against a plate. Very quiet and efficient
but the output was a little coarse - maybe it is more accurately
described as a chipper.

I spread a lot of it out 1"-2" thick straight away over my
rhubarb and gooseberry bush bed. Looked awful the first year but
weathered and merged into the background. It took years for the
soil to reappear. In the meantime, decomposition made a barren
plot very fertile to the point of not ever needing fertiliser,
whereas before nothing would grow without it. It also kept the
weeds down very well.

W.