FACTORS AFFECTING DECOMPOSITION:
are three environmental factors affecting the interwoven chemical
and microbial breakdown of the organic matter.
can be defined in the terms of availability of oxygen. Aerobic
decomposition means that the active microbes in the heap
require oxygen, while in anaerobic decomposition,
the active microbes do not require oxygen to live and grow. Temperature,
moisture content, the size of bacterial populations, and availability
of nutrients limit and determine how much oxygen your heap uses.
amount of moisture in your heap should be as high as possible,
while still allowing air to filter into the pore spaces for the
benefit of aerobic bacteria. Individual bacterial hold various
percentages of moisture in compost and determine the amount
of water that can be added. For example, woody and fibrous material,
such as bark, sawdust, wood chips, hay and straw have the
capacity to hold up to 75 to 85 percent of moisture. " Green
manure", such as lawn clipping and vegetable trimming are
able to hold 50 to 60 percent moisture.
minimum moisture content at which bacterial activity takes place
is from 12 to 15 percent. Obviously, the closer the moisture content
of a composting mass approaches these low levels, the slower will
be the compost process. As a rule of thumb, the moisture content
becomes a limited factor when it drops below 45 or 50 percent.
is an important factor in the biological of a compost heap. Low
outside temperatures during the winter months slow the decomposition
process, while warmer temperatures speed it up. During the warmer
months of the year, intense microbial activity inside the heap
caused composting to proceed at extremely high temperatures. The
microbes which decomposes the raw materials fall into basically
two categories : mesospheric, those that live and grow
in temperatures of 50 °F to 113 °F (10 °C to 45 °C),
and thermophillic those that thrive in temperatures of
113 °F to 158 °F (45 °C to 70 °C). The initial
heat heap phase that most garden compost goes through is thermophillic.
The organic material dehydrated very quickly in this phase and
should be kept aerated and moistened. The high temperatures are
beneficial to the gardener because they kill weed seeds and germs
that could be detrimental to vegetation. The next holds at 100
°F for a while and different microbes predominate. Then finally,
the ambient phase where the pleasant earthly odor originates and
material has produced compost.