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by:
Lorraine Johnson
illustrations: Katy Dockrill |
Compost
Happens |
| The
secret to making quick gardener’s gold instead of a slow, stinking
mess requires—like everything else—balance |
No matter what you do, organic materials eventually break down.
Decay is inevitable. But—and it’s a big but—there’s a difference
between controlled decomposition, as found in a healthy, working
compost pile, and the smelly mess of rotting materials in a
bin gone bad.
Anyone who has had a bad composting experience (and I confess
to having had a few over the years) can tell horror stories
of scary-movie magnitude, but the good news is that it’s relatively
straightforward to create healthy, sweet-smelling compost (often
dubbed “gardener’s gold” by compost enthusiasts). And the benefits
are beyond doubt: compost returns nutrients and organic matter
to the soil, feeds beneficial micro-organisms and earthworms,
and improves the texture, oxygen-retaining capabilities and
moisture-holding capacity of soil. In other words, compost helps
create healthy gardens. Beyond its benefit to gardens, however,
there’s another compelling reason to have some form of composting
system in your yard: putting garden and kitchen waste in a compost
pile removes these materials (or “good garbage,” as my grandmother
used to say) from the waste stream. As debates about landfill
sites and garbage incineration heat up across Canada, we can
all do our bit to reduce the waste our households contribute
by heating them up—literally—in a compost bin.
Composting can be seen as a kind
of culinary alchemy in which a balanced recipe of ingredients
is mixed in a bin or pile. As the mixture breaks down it generates
heat, which accelerates the process, and it’s eventually transformed
into finished compost. The cooking metaphor is apt.
You can take the low-tech approach
by simply piling garden cuttings in a corner of the yard and
ignoring them for a year. But if you follow the method described
on these pages, your compost should be ready to harvest in three
to six months.
Choose a Container
First, you need some kind of structure to contain your composting
materials. Options range from store-bought, plastic single bins
to homemade, wooden three-bin units. One of the most popular
ready-mades is the black plastic SoilSaver, which has a capacity
of .36 cubic metres, a locking lid, and doors at the bottoms
of two sides. The advantages of this kind of unit are that it’s
easy to dig finished compost out of the side doors, and it’s
relatively pest-proof (particularly if you put bricks on top
of the lid—urban raccoons have been known to undo the locking
mechanism). The black plastic helps the pile to retain the heat
it generates, and also to trap solar heat, assuming it’s in
a sunny location—preferable, but not necessary.
Three-bin units are useful if you’ve got a large property, since
you’ll have more leaves, grass clippings and plant debris. When
the compost in the first chamber is partially finished, use
a pitchfork to transfer it to the second bin, making sure the
coarser materials around the sides of the original pile are
in the centre of the new one; start from scratch in the first
bin. A few weeks later, transfer material in bin two to bin
three, and bin one to two, starting over in bin one. This is
a good way to aerate the pile; also, materials in the three
bins are at various levels of decomposition—an efficient way
of making compost.
No matter what type of bin you
use, cover it to keep pests out and heat and moisture in, although
it also needs vents for airflow. (This is why wooden models
typically have spaces between the slats.) Another selling point
is a wide opening at the top so you can stir the mixture easily.
The Ingredients
Controlled and speedy decomposition is all about balance. If
your compost pile is too full of “browns”—compost lingo for
carbon-rich materials such as dead leaves, straw and dead plant
stalks—then your pile will be slow to decompose. On the other
hand, if the pile is too full of “greens”—nitrogen-rich materials
such as fresh food scraps and grass clippings—it will turn slimy
and smell bad. The goal is to have equal amounts, roughly by
weight, of browns and greens. The ideal carbon-to-nitrogen ratio
for decomposition is about 30:1. Dead leaves (browns) have a
C:N ratio of approximately 40:1 to 80:1, while fresh grass clippings
(greens) have a ratio of 19:1. But there’s no need to obsess:
your eyes, nose and common sense will tell you if you’ve got
roughly the right balance.
The other ingredient you should add to the pile is soil; it
supplies starter micro-organisms—bacteria and other microscopic
organisms that digest and excrete organic materials, breaking
them down. Soil also masks the odour of food waste, which discourages
pests from visiting your pile—and it’s easier to keep pests
out than to dislodge them once they’ve arrived.
Store-bought compost accelerators
are generally nitrogen-rich to balance the bulk of compost materials—dead
leaves—that are heavy on carbon. But if you’re already adding
a balance of green and brown materials, there’s no need to include
supplemental nitrogen.
Recipe Instructions
To achieve even greater balance and the speediest possible decomposition,
layer the browns and greens, and build the pile all at once.
This works well when you’ve got a lot of grass clippings for
greens and dead leaves for browns. I always keep a big bag of
dead leaves by my bin—that way, I have a ready source of browns
even in spring and summer. But who wants to stockpile rotting
vegetables? Add them for greens as they become available.
Begin with a mixture of dead
plant stalks—this loose, lower layer permits air circulation
at the bottom of the pile, which is important to controlled
decomposition. (A densely compacted pile may start to smell
bad.) Then, add a layer (approximately 15 centimetres) of greens,
such as coffee grounds, vegetable peelings and grass clippings.
Sprinkle a 2.5- to five-centimetre layer of soil over the greens,
and add a thick layer (approximately 30 centimetres) of dead
leaves, straw or dried garden clippings. Repeat this layering
process of greens, soil and browns until the bin is full.
 Cooking
the Pile
Along
with the correct ratio of browns to greens, there are two other
factors that contribute to speedy, effective composting: adequate
moisture and oxygen flow. Again, it’s a matter of balance. The
materials should be as moist as a wrung-out sponge; if you’ve
piled in dry leaves, for example, it’s a good idea to run a
garden hose to the top of the pile and soak it for a few minutes.
Or, you can add water to each brown layer as you build the pile;
chances are the green layers are already moist.
The best way to ensure adequate
air movement is to stir the pile every week or so. You can use
a commercially available compost turner, a pitchfork or a sharp
stick. (I’ve even used an old broom handle.) While you’re turning
the pile, check the moisture level, and add water if necessary—think
of the wrung-out sponge for guidance. Move the materials at
the sides to the centre, where the temperature can reach 52°C
or more, so all materials get cooked.
Earthworms around the base of
the pile are a good sign; they help micro-organisms break down
the debris.
Fresh
from the Oven
| SPOILING
THE POT |
| While
most organic materials can be added to a compost
pile, a few waste categories should be avoided because
they may carry pathogens or attract pests: meat;
fish; dairy products; fatty, oily foods; bones;
used cat litter and other pet waste. As well, some
materials, such as corn cobs and small twigs, take
a long time to break down, so you may need to screen
them out of your finished compost and put them in
again to decompose further. |
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You’ll
know your compost is ready when it looks and smells like soil.
Dig it out; screen out any small bits of undigested materials
and throw them back in. Spread compost throughout the garden:
top-dress your lawn with a thin layer, dig it into new beds,
or mound it around the base of established plants. You’ll soon
discover, as committed compost enthusiasts everywhere have,
that you can never have enough.
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