(Materials & methods
to ensure quality compost)
Climatic conditions, particularly temperature, wind, and rainfall
influences the composting process. The lowest temperature at which
composting might be satisfactorily done, is not known. A slightly
larger compost pile in winter weather will reduce the heat loss per
Organic compost material has excellent insulating properties. A
steep temperature gradient exits at the outer surface of compost
stacks. The difference in temperature may be several degrees Fahrenheit
per inch of material. Composting can can occur at severe freezing
temperatures, providing snow conditions do not interfere with turning
and the snow becomes mixed with the compost. Turning would not have
to be done quite as often as in warm weather, because there would
be a longer temperature recovery period after each turn when the
colder exterior of the pile was turned into the interior.
Strong winds markedly lower temperatures on the windward side of
a compost pile. Two factors play an important role: (a) the coarseness
of the material, which affects the porosity and dessication of the
pile, and (b) the moisture content. Unshredded or coarsely shredded
material has a greater porosity and permits greater penetration of
wind into the pile. Consequently, more evaporation takes place. When
the material becomes too dry, bacterial activity is inhibited. Shredding
or grinding to produce a
maximum particle size of about 2 inches provides a more homogeneous
mass that is not as easily penetrated by winds. Thoroughly wetting
the exterior of the pile, particularly on the windward side, will
reduce wind penetration and permit the interior high-temperature
zone to extend nearer to the surface of the pile.
In an area of strong prevailing winds, a windbreak could be built
to protect compost piles. This should seldom be necessary, however,
since increasing the size of and wetting the pile will control temperatures,
and all material will be exposed to high temperatures by turning.
Wind cooling and drying of compost piles is of little significance
when piles or bins are used, since the material is protected on all
sides except the top, which wetting will protect.
To avoid problems with rain, piles can be finished with a rounded
top so that the rainwater can run off, and adequately drained to
ensure they are not in standing water. Heavy rains accompanied by
high winds will penetrate a pile of coarsely shredded material as
much as 12 to 15 inches on the windward side, but the effect on large
piles can be overcome by subsequent turning.
Turning should not be done in the rain, because the material may
become waterlogged. If the material cannot be turned on regular schedule
owing to rain, it is better to let it become deficient in air for
a short time than soaked. Rainy weather can present more of a problem
when composting is done in pits or bins. The top of the pit should
be rounded to turn the water, which will, however, seep along the
edges to the bottom. The bottom should therefore be adequately drained
to remove the water and to allow a minimum of penetration into the
compost. In rainy areas, pits should be lined with concrete, brick,
or masonry, and provided with tile drains. Or roofs could be built
over the bins or pits to protect them from rain.
During rainy weather, shredding or grinding, and the segregation
of the materials should be done under cover. Facilities for storing
the incoming materials for a short time should be provided, so that
stacking or piling does not have to be done during rain.
Composting can be done satisfactorily in relatively cold climates
or in areas of considerable rainfall with a minimum of roofed buildings.
Heavy snowfall will greatly hinder continuous composting operations
and removal of snow from the composting piles or bins will usually
be required. Material will not become anaerobic or create an odor
nuisance during really cold weather. Hence, if an ample composting
area is available, the material can be allowed to stand for long
periods without turning until the weather is favorable.