Composting Basics
Composting is a natural biological process by which biotic material is converted into a soil-like product called
compost. The composting process works with the help of decomposers such as bacteria and fungi,
combined with air and moisture, to break down biotic material.
Anything biotic, be it a carrot, leaves, coffee grounds or a banana peel, can be recycled through the
composting process. While any biotic material will naturally decompose over time, it is important to be
aware of and manage the many factors that can influence the speed, process quality, and end result.
Decomposers responsible for breaking down or decomposing the biotic materials, need food, air and water.
Preparing the biotic materials properly as well as providing the right conditions for their work helps speed
up and effectively manage the process.
Composting is composed of
(1) brown, carbon-rich materials, such as dry leaves or dried grass and
(2) green, nitrogen-rich materials such as fruit and vegetable peels, coffee grounds and freshly-cut grass.
Temperature
The temperature of the compost pile gives a great indication of the activity of the decomposers. They give
off heat as they work, causing temperatures to rise. As the temperature increases, the conditions change,
with different types of decomposers taking over, being able to live better in these hotter conditions.
Temperatures will begin to drop as the biotic matter is consumed, resulting in the process slowing down.
The addition of more biotic materials as well as mixing of the pile will help reinvigorate the process.
External air temperatures also have an impact, with the warmer months of Spring-Summer-Fall increasing
decomposition activity and the coldness of Winter slowing down the composting process.
Oxygen level
The organisms need oxygen to function, including most bacteria and decomposers. Frequent mixing or
aerating of the compost enables oxygen to enter the pile. When there is enough air, decomposers can work
faster to break down the biotic materials. When oxygen becomes used up or depleted, without additional
mixing, the decomposition process slows down. With limited oxygen, some bacteria also produce
unpleasant odors which smell like rotten eggs.
Particle size of material being decomposed
The speed or rate of decomposition is affected by the organic matter’s particle size. Chopping or shredding
the material --- ideally to about 5 cm pieces --- helps increase surface area. Since most decomposition
occurs on the surface of biotic particles, a larger surface area would speed up the breakdown of materials
for composting. If the particles are too small, however, they might prevent air from flowing freely through
the pile.
Some large particles such as wood chips, chopped branches, pinecones, or corn cobs are often added to
piles to ensure airflow. At the end of the composting process, the larger particles that have not
decomposed can be filtered out from the compost and reused.
Moisture level
The compost pile should be at a moisture level of between 40 and 60%, most often described as feeling “as
moist as a wrung out sponge”. A compost pile needs enough moisture to function properly without being
so wet that it blocks airflow. Water helps transport substances and nutrients within the compost pile.
“Green” material for composting contains some moisture in varying amounts, but moisture also might come
in the form of rainfall or intentional watering.
https://www.epa.gov/sustainable-management-food/types-composting-and-understanding-process#aerate
dturned
http://www.gov.pe.ca/photos/original/4h_NRNcompost.pdf
