In article ,
Peter wrote:

This is what I was taught:

Carbon is woody material.
Nitrogen is contained in green leafy material.

That is true, but there is less in green leafy material than you may
think. There is far more in mature pulses (and many other seeds)
and of course meat and animal waste.

The bacteria that break down the carbon use nitrogen during the process, if
there is not enough nitrogen they cannot do their job.

Also true.

A carbon : nitrogen ratio of (25-30) : 1 is required.
That is 25-30 times as much woody stuff to green stuff.

Neither is true. A ratio of something like that will decompose pretty
fast, but isn't needed. At the low end of the scale, the rate of
decomposition will be limited by the availability of nitrogen, but it
will proceed quite happily as long as there is SOME. And, because
green leaves contain far more carbohydrate than protein, you need
more like pure green leaves to get that ratio (depending on the leaves,
their state of growth etc.)

Urine contains nitrogen, so if you think you are short of nitrogen, you have
a free supply on tap (so to speak).

Quite :-) Or just sprinkle some general purpose fertiliser on.

Bacteria also need oxygen, so you have to keep the heap well aerated by
turning it from time to time.

MOST bacteria. The ones that work without oxygen tend to produce
more foul-smelling molecules than the ones that work with oxygen,
which is why the compaction of grass clippings causes a stinking
mess.


Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email:
Tel.: +44 1223 334761 Fax: +44 1223 334679