placement and structures
There are many ways, such as bins, barrels,
pits and windrows to compost organic matter.
Open piles, windrows, or bins are the most
widely used methods for aerobic decomposition
and maturing of organic refuse. Exact use
and arrangement of these systems depends
on local requirements of materials, labor,
cost of systems, climatic conditions such
as temperature, rainfall, and wind.
To aerobically maintain the composting process
by frequent turning for aeration, windrows,
piles and bins above the surface of the ground
are more efficient than pits. On the other
hand, if the decomposition is to be entirely
anaerobic or aerobic only during a short
initial period, pits 3 to 4 feet deep and
varying in length and width in accordance
with the daily quantity of raw material should
Material in aerobic composting piles should
be loosely stacked to allow space for air
in the interstices. Windrows or piles may
be of any length, but the height of the pile
is critical. If piled too high, material
will be compressed by its own weight, thus
reducing pore space, which results in increased
turning labor (costs) or longer composting
time as anaerobic conditions develop. In
some instances, the maximum practical height
may be governed by the equipment used for
stacking the feedstocks, or by the tendency
of the pile to become excessively hot. Large
piles in warm weather may reach temperatures
excessively high for bacterial life. Some
have even caught fire.
Piles that are too low lose heat rapidly.
They do not get hot enough for destruction
of pathogenic organisms and decomposition
Also, if the piles are too small, loss of
moisture may be excessive, especially near
the edges, and decomposition slows.
Five to six feet is about the maximum height
for any pile, and 3 feet is the minimum for
most shredded fresh organic matter. The height
can be greater in cold weather than in warm
Thoroughly mixing compost materials in bins,
windrows or piles provides quickest and most
complete decomposition. The pile may normally
be started directly on the ground. To ensure
aeration to the bottom of the pile and improve
drainage, dig a trench across the base of
the area and cover with stiff wire mesh (hardware
cloth) before adding material.
Home gardeners may not have enough materials
daily for windrows. In this case circular
or rectangular piles 4 – 6 feet in diameter
and 3 to 5 feet high works, with a rounded
top for shedding rainwater.
For shallow pits, either the walls and bottom
of the pit are lined with brick or masonry
or the natural earth is tamped and packed.
The material is stacked to a height of 1
foot or more above the ground, making a total
of 3 to 4 feet. The material can be turned
in the pit as often as necessary to provide
the high temperatures and aerobic conditions
as required. When pits are used, a smaller
stack surface is exposed to the air, and
the walls and bottom of the pit provide some
insulation against heat and moisture loss.
Any type of pit should be lined and is usually
provided with a chimney and trenches, or
a porous bottom, for aeration and drainage
of liquid seepage from the pile. The same
shape trenches without aeration and drainage
channels and without masonry lining may be
used. But unless pits are lined, the walls
are apt to crumble and the shape of the pit
becomes irregular. When hand labor is used,
turning the material in a pit may be about
the same as in a stack on the ground surface.
One effective method involves composting
in pits approximately 3 feet deep by a system
of providing aerobic conditions and high
temperatures for the first few days and then
anaerobic conditions for 4 to 6 months. Material
is mixed in the pit. There is sufficient
oxygen in the initial stack for a high temperature
to be produced by aerobic organisms during
the first few days. High temperatures are
usually retained for two weeks or so, owing
to the insulating properties of the stack,
even though anaerobic conditions may exist
after the first few days. Leave the material
to compost in the pit with no turning for
about three months.
3) SHEET or TRENCH COMPOST
To sheet compost, work a thin layer of material
such as leaves into the garden in the fall.
By spring, the material should be broken
down. This would not be appropriate for materials
such as wood chips that would take a longer
time to decompose, and might tie up soil
nitrogen in the spring, making it unavailable
to other plants.
For trench compost, dig a trench 8 – 15 inches
deep, bury the feedstocks, then cover back
up with soil. It takes about a year to decompose.