ingredients: Decomposition Column ingredients can include
leaves, grass and plant clippings, kitchen scraps, newspapers, animal
manure and soil. If you are interested in how fast things decay,
try building two identical columns, but fill them with leaves from
two different species of trees. Try adding fertilizer to your column,
or water from a pond or river. How do you suppose differences in
temperature, light or moisture will affect the decomposition process?
The time it takes: You'll begin to see
mold and other evidence of decomposition within the first few days
after filling your column.
Two or three months is plenty of time to see soft organic
material such as leaves, fruits, vegetables and grain products decompose
dramatically. (The term organic applies to something that is derived
directly from a living organism.) Bark, newspapers and wood chips
all take longer to decompose, though they still undergo interesting
changes in two to three months.
How wet?: Keep your column moist in
order to observe more rapid decomposition. Avoid flooding your column
or it will become waterlogged. This can create an anaerobic
environment, or one completely lacking oxygen, in which certain
microbes create particularly vigorous odors.
Using your nose: Odor is a by-product
of decomposition, and can tell you a lot about the materials in
your columns. Odors may be strong at first, but can mellow and become
musty with time. Classrooms full of odorous Decomposition Columns,
however, have been known to try the patience of colleagues and building
supervisors. The strongest odors arise from animal products such
as meat and dairy products. Grapefruit rinds and grass cuttings
can also produce strong odors. Why is this so? If you use food scraps,
mix in plant matter such as leaves, twigs and dried grass to temper
odors. Layering soil on top of contents also lessens the odor.
Increasing the number and size of air
holes in your column will increase air exchange. How do you
think this will affect decomposition? Keep holes small so fruit
flies stay inside.
If your classroom fruit fly population booms anyway,
make a Fruit Fly Trap!