Compost basics: how to make composting work for your organic garden
Compost is one the best things the organic gardener can get their hands
on. It nourishes plants, giving them many micronutrients and trace elements
not found in most organic fertilisers.
Plus it also helps protect your plants from diseases. And the best part
about compost is you can make it yourself.
What's in compost?
Compost is simply organic matter that has broken down. Anything that
once lived can be composted; although there's some things that are better
composted, and others best left out. The building blocks of good compost
is what's called "dry browns" and "wet greens".
Dry browns are items high in carbon. Try using:
Wet greens are naturally high in nitrogen and include:
Some lucky seaside gardeners in cooler climates can add kelp (a form
of sea weed).
What to avoid:
you can include old weeds, but we only use weeds that haven't flowered
(otherwise you could add weed seed to your compost - not a good idea);
don't add your dog or cat manure (their worming treatment can also
kill off composting worms);
throw diseased plants away (adding them to your compost could potentially
spread the disease further through your garden);
keep meat and bones away from your compost bin as they'll attract
flys, rats and other vermin, and;
don't include citrus peels (they're too acidic for worms).
A rough science
While there is no hard and fast rule on what proportion of dry browns
and wet greens you should mix, accepted gardening wisdom supports 5 parts
dry brown : 1-2 parts wet greens. Any ratio will work given time, but
to get your compost really cooking it's best to have a lot more dry browns.
Piles, holes, bins and tumblers
Give it 12 months and a pile of organic matter will eventually break
down into compost. You can pile all your organic goodies in some out of
the way place in your yard. You might consider using a tarp to cover the
pile to keep excess rain leaching out nutrients, keeping stray wildlife
away and also helping to "heat up" the pile.
Some gardeners short on space dig trenches in their beds which they fill
up with compost ingredients, planting into these 6 months later.
You can also buy plastic compost bins (usually from most local councils
at cost price) or make your own with timber and chicken wire. Just a reminder
that according to Organic
Gardening magazine CCA treated pine has been found to leach arsenic
and other toxic substances, so make up your own mind on what timber you
use if building bins.
We use the fastest compost making device known to mankind - a tumbler.
By turning your bin daily you can accelerate decomposition significantly.
This means more compost each year and it's much quicker too (often ready
in 2 or 3 months). Mind you this is also the most expensive option, but
you get what you pay for.
Getting things cooking
Composting happens when bacteria starts decomposing organic matter down
to more basic elements. The bacteria start heating up the pile to 120-140F
degrees (50-60C degrees) where (in theory) weed seeds and bad bacteria
are killed off. We say in theory as we've often had seeds germinate in
completed compost - which is why we don't add flowering weeds. Worms also
enter the compost and work away in cooler pockets where they make vermicast
(worm manure) which is good news for your garden (it's great stuff)!
Speeding things up
To get your compost quicker there are some little tricks you can follow:
The smaller the better - If you've got a chipper or shredder
you've got a license to make pure black gold. The smaller your organic
matter the easier it is for bacteria and worms to break it down. Even
if you don't have one of these machines you can still speed things
up. Chop up your kitchen scraps or get hold of shredded office paper.
Get the air in - using a tumbler, or even turning the pile
with a pitch fork will get air into the pile. Oxygen is needed for
bacteria to do their work. More oxygen means faster compost. Some
gardeners get very technical in pumping more air in. They'll build
their pile around PVC piping which have had holes drilled into the
pipe. This captures the air and pumps it into the heart of the pile.
Damp not wet - to promote breaking down the the compost ingredients
it's important to keep the pile moist inside, but avoid getting it
slushy. Compost that is too wet can become sour and smell.
Getting the ratio right - as mentioned before a high proportion
of dry browns to wet greens will help speed things up decomposition.
It's also important to make sure things are mixed well. Grass clippings
clumped together will take a while to break down.
The wonders of activators - by keeping back some of your last
batch of compost, and putting it into your new pile you can help move
things along. As good bacteria and worms are already present it "kick
starts" your next bunch of compost.
You can tell your compost is ready when it's rich, loose and dark. It
should no longer look like what first went into your bin.
Now what do you do with it? It depends on whether you're using your compost
to enrich the soil for growing, or protecting against diseases.
To improve the soil add anywhere between 1-2 inches of compost, digging
it few inches deep. It's just like adding manure, mixing it into the soil
as a whole, not just a distinct layer in the soil. For disease protection
compost is generally used as a mulch. We still like to put another layer
above this (like straw or sugar cane mulch) to stop the compost drying
out under the warm sun.
You can also use compost as a pick me up during the hungriest growing
season of your plants. This might mean mulching around corn stalks when
in flower or cobs are forming, or mulching tomato stems to boost yields.
Or you can mix some compost with water to make compost tea - just like
liquid manure but using compost. Or use compost tea as a folliar spray.
Sounds great, but my compost isn't working out
Here's a trouble shooter's guide to help fix any problems with your compost
It smells! A strong ammonia smell is quiet common 3-7 days into cooking
the pile. But if the ammonia smell doesn't go away you might have
too many wet greens to dry browns. Pull your pile apart to dry out
its contents or add and mix in more dry browns.
Done that, it still smells. OK, maybe you're not getting enough air
into your bin or pile. Oxygen is a vital ingredient to get microscopic
bacteria working for you. Some solutions: build a heap around PVC
piping with holes drilled in to suck air deep into the pile; get air
in by thrusting stakes into the pile and withdrawing them (hopefully
the holes won't collapse); regularly turn your pile or invest in a
It's too wet. This will mean your pile probably isn't heating up
enough. Pull it apart to try to dry things out a bit. If your compost
is just a heap, think about covering it with a tarp or heavy plastic.
23 October, 2008
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