Last weekend we had a compost 101 class
at Concho. We went through the processes that make a compost pile successful
and the things that gardeners need to know to make sure the process
goes well. I know that not everyone was able to make it out to the class
so here are answers to some important questions about composting:
What is compost?
Compost is not the same thing as soil.
Compost is considered a soil additive, because it improves the
quality of almost every type of soil. Compost helps sandy soil retain
water, and it helps clay-heavy soil drain better. The active colonies of
micro-organisms in compost help plants to fight diseases. Healthy
plants start with healthy soil.
How does composting work?
Many different types of micro-organisms
work together to digest plant matter into the finished product that
we use. Both bacteria and fungi are at work in a compost pile. When
enough digestion is taking place in the pile, it starts to heat up.
On a cold day, you can even see steam! We want to give these
organisms the ingredients they need to work fast and heat up. Heat
kills seeds and diseases. After the process has stabilized, which can
take a few weeks to a few months depending on the amount of care a
pile is given, we are left with an earthy smelling soil additive.
How can I make this process successful?
The organisms that make good compost
require four basic things for success. The first two are carbon and
nitrogen. These two elements are present in all organic matter. What
is important is the ratio between these two elements in the pile. The
optimal ratio is C:N 25-30:1. We control this by adding different
amounts of materials with different ratios. Things that are green and
wet, like vegetables or coffee grounds, usually have C:N ratios of
25:1 or less. We balance these “high nitrogen” materials by
adding things that are brown and more carbon rich like dried leaves,
which are around 70:1 depending on the species. This link has a table
with some common items. The C:N ratio is approximate, and it will
never be exact. We just try to make sure that the piles don't get too
full of dry leaves and carbon heavy materials because then they cool
down and work slower.
Water is an essential item for life so
it is essential for the compost organisms. A pile should be damp
throughout. If a lot of dry material is added, it is important to add
water. Paper does not hold moisture at all, as well as being devoid
of nitrogen and micro-nutrients, so we try to keep it out of our
piles in large amounts.
Oxygen is necessary for the bacteria
in the pile. The difference between compost and landfill is that
landfills don't have oxygen. If the pile is smelly, there's a good
chance it needs to be aerated by turning it or poking holes in it.
I have a big bag of banana peels/apple cores/dead garden plants/tea bags/coffee grounds. What should I do with them?
Well if you have a backyard at home,
you should consider a home compost pile! Otherwise, the Concho piles
accept donations like this. Our piles are a little bit picky though.
First, make sure to take all the stickers off your fruits. Those
little stickers don't break down. We want to keep our compost trash
free. If the garden plants are big, be sure to cut the plants into
small pieces. When adding to a pile, be sure to mix the materials in
to the pile. If we leave stuff sitting on top, it just dries out or
attracts flies.
I have a big bag of newspapers/cardboard/”compostable” plastic/large sticks/whole pecans/metal/wrappers/”compostable” plates and cups. What should I do with these?
Please do not add these things to our
piles! Adding metal and plastic to a compost pile is practically
littering. Newspapers and cardboard are technically biodegradable,
but they do not hold much moisture or have any nutritional value.
Better to recycle your paper and cardboard. Industrially manufactured
products with the label “compostable” take a long time to
decompose and are only suitable for industrial compost facilities.
Austin is working on curbside compost collection.
How can I help? How can I learn more?
Come out to the garden on a workday,
every Sunday from 9:30-12:30. We are also having another compost
class on March 24th, so if you missed the first one you
should definitely attend the next one! More reading about compost can
be found here or at the public library.
