and gluggy compost heap
this year I purchased a composting bin and thought this would be
a more environmentally friendly way of disposing of garden waste,
vegetables, etc (as well as adding to my gardens). However, nine
months on my compost is gluggy, smells foul, and looks more like
something the cat dragged in.
compost pile needs four components: carbon, nitrogen, oxygen and
moisture. The interaction of these components, plus the heat generated
by microbe activity, generates the breaking down of organic matter.
The first two components
can be found in organic materials. 'Greens', for example, provide
nitrogen fresh grass clippings, plant trimmings, green leaves,
and fruit and veggie scraps. 'Browns' provide carbon sticks,
twigs, sawdust, hay, pine needles and wood ash. Too much nitrogen
and your compost pile will turn to mush. Too much carbon and the
decaying process will be hindered. A good compost pile requires
one part green to about three parts brown.
The next ingredient,
oxygen, is absorbed from the air and enables micro-organisms to
decompose the material. Micro-organisms require a continuous supply
of oxygen, and for a compost heap to break down rapidly, air needs
to be able to circulate freely. This is achieved by turning the
pile regularly and using compost bins with holes for aeration. If
a compost heap begins to smell, there is not enough oxygen in the
Water is another necessary
ingredient, but if the compost heap is too wet (or too dry, for
that matter) the organic material cannot decompose. Too much water
will decrease the amount of oxygen in the pile (and thus make it
smelly), so keep the pile covered to avoid excess rainwater getting
in. The pile should be damp but not soggy.
Mix in more brown material,
and apply some garden lime or dolomite to 'sweeten' your heap. Lime
reduces the acidity (and smell) caused by excessive nitrogen-rich
When adding nitrogen-rich
material to your heap, mix with dry leaves, straw, sawdust or other
'brown' material even shredded newspaper if others are not
readily at hand.
A clever trick to allow
air to the centre of your heap is to add a cylinder of chicken wire,
about 15 to 20 cm in diameter, and tall enough so that it extends
above the heap. However, if you're using a commercial compost bin
with holes, this should not be necessary.
by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor
of Resource Management.
with permission from NZOOM Home and Garden content,
from the previous
The views expressed here are not necessarily those of the RNZIH