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Old 07-11-2009, 08:06 AM posted to rec.gardens
sherwin dubren sherwin dubren is offline
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First recorded activity by GardenBanter: Nov 2008
Posts: 110
Default Are fall leaves toxic?

FarmI wrote:

Why do you make a distinction between leaf mold and compost? Aren't
they the same thing?


No, they aren't the same thing even though compost may have some leaves
included in it.

Leaf mould is made by piling leaves and then letting the pile rot down for a
couple of years without disturbance.


My leaf piles in compost bins take only one year to process. I do not
add any enhancers to them, except for water. It is key to keep these
leaf piles damp, as I can see dry portions never cooking. It is also
important that they are chopped up. Otherwise, they mat together and
this also prevents decomposition.

Leaves have lignin in them

My checking on the web says that stems and wood contain more lignin
than leaves, so I don't think this is the reason for them taking so
long to break down.

and thus
they take a long time to rot and, unlike compost, it is a cold rotting
process rather than a hot one.


Now, my compost piles have some grass clippings in them, so this may
account for the fact that they get nice and hot, even steamy on colder
days. However, I have seen recommendations of 2 parts of grass to
every part of leaves for a pile. In my case, I think the grass is
than 10 percent of the total, but everything cooks just fine in one
year.

Leaves decompose by using fungal
decompostition IIRC whereas compost is made by bacterial decomposition
(again, IIRC).

Leaf mould is valuble as the end result of decayed material is more durable
in the soil than 'normal' compost (because of the lignin).


From what I read, lignum is present in all vascular plants, and occurs
in higher amounts in wood than in leaves.

Another difference is that Leaf mould is made of just leaves and compost is
made of a combination of materials and includes a high nitrogen content
which is not present in leaf mould.


Except for processing time, I don't think the nitrogen affects the
plants covered in leaf compost. There are more natural ways the soil
to fixate itself with nitrogen. My experience is that leaves will
break down in a years time, assuming the pile is kept consistently
damp and the leaves are chopped up.

Sherwin

Some leaves take forever to turn into leaf mould, for example, Plane tree
leaves.