Organic Waste and Home Composting - Palmerston North City Council

What is organic waste?
Organic Waste and Home Composting
Organic waste is biodegradable waste, or waste that can be broken down by micro-organisms. Organic
waste includes materials such as wood, leaves, bark, grass clippings, paper, and food waste such as fruit
and vegetable peelings.
Why should we care about organic waste?
During the period of January 2006 to February 2007 35,240 tonnes of organic waste was sent to landfill by
our City alone. Organic waste made up 32% of the total waste we disposed to landfill with garden waste
the highest percentage of all waste types sent to landfill at 27% 1 !
Did you know?
Organic matter in a landfill is broken down through anaerobic decomposition (without air) to produce
leachate and methane. Methane (CH 4 ) is a powerful greenhouse gas that remains in the atmosphere for
approximately 9-15 years. Over a 100 year period methane is over 20 times more effective in trapping
heat in the atmosphere than carbon dioxide (CO 2 ) 2 .
Conversely if organic matter such as paper, cardboard, kitchen and green waste is composted it can
produce a range of beneficial products from coarse mulch to fine compost.
How can we keep organic waste out of the landfill?
The 32% of organic material being sent to landfill could be diverted through initiatives such as home
composting and worm farming. For information on worm farming refer to the Council’s information sheet
Worm Farming – How to Care for your Worms.
What is composting?
Composting is a natural process in which micro-organisms convert organic waste such as leaves, vegetable
peeling, grass clippings and paper into a rich soil conditioner.
What are the benefits of composting?
Apart from reducing waste to landfill composting is a simple, cost effective and natural way to recycle
your organic kitchen and garden waste and turn it into a beneficial product for use in your home or
garden. When compost is used in your garden the end result is an improvement in the nutrient levels of
the soil, as well as to the soil structure. It also prevents erosion and improves the water holding capacity
of your soil.
1 Draft Waste Minimisation Plan 2009, Figure 3 What’s In Palmerston North’s Waste, Page 6.
2 http://www.epa.gov/methane/
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Principles to making a good compost
Making useable compost is easy; all the hard work is done by micro-organisms. The key to composting is
to keep the micro-organisms that process the organic waste healthy – they need food, air, moisture and
warmth (just like us).
Browns
Browns are carbon rich materials such as paper, sawdust, straw, leaves, cereal boxes, cardboard, napkins,
paper towels, tree clippings, vacuum cleaner dust, egg shells, woody materials and wood ash (materials
that are tough and dry).
Greens
Greens are nitrogen rich materials such as raw uncooked kitchen scraps and vegetable peelings, tea bags
and leaves, coffee grounds, grass clippings, soft garden debris, sheep or horse manure (materials that are
high in moisture and rot away quickly).
Moisture
Your compost should be moist like a wrung out sponge. If you find the compost is too dry add a little
water. If it is too wet add some of the dry ‘brown’ materials listed above.
Air
Like all living creatures that breathe oxygen, aerobic micro-organisms need air to live. It is important to
allow air into the compost. You can do this by adding scrunched up or shredded paper, egg cartons, toilet
paper rolls or dry twigs to create air pockets, or dig over your compost using a garden fork to encourage
air circulation.
What should NOT be put into your compost
Meat Grease Fat Bones Cooked food (may attract vermin)
Weeds Dairy Oil Treated wood Non-organic material
Cat and dog faeces are not recommended as they can cause odour problems, may contain parasites and
there is little nutrient value in them.
Compost can be made in a simple free standing pile on the ground or you can create compost in a bin or
container. You can make a compost bin yourself at little or no cost from wood, bricks, concrete blocks or
any other suitable recyclable material. Commercial compost bins are available for purchase at your local
hardware or gardening stores.
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Follow these easy steps to make your own home compost:
Within a couple of days of creating your compost heap it should begin to heat up. This will be the
beginning of the composting process. Regular turning of the compost heap is an important part of making
good compost.
Did you know?
Compost can:
‣ Suppress plant diseases and pests
‣ Reduce or eliminate the need for chemical fertilisers
‣ Promote higher yields of agricultural crops 3
Turning your compost
For the best composting results you should turn your compost heap once every 4 to 6 weeks. Turning
should be done in a manner that allows all the material from the sides to be moved into the centre.
Turning your compost regularly should reduce the time to produce useable compost from 6 to 12 months
to only 4 to 6 months, depending on climatic conditions and the size and composition of your compost
heap.
3 http://www.epa.gov/epawaste/conserve/rrr/composting/basic.htm
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Using your compost
Your compost is ready when it looks like potting mix (dark brown in colour with an earthy smell). It may
be a bit lumpier than the potting mix you buy from your local gardening store with bits of twig and egg
shells in it, but do not worry it will still be just as effective. Simply sieve out the larger items and return
them to the compost heap for further processing.
Here are some tips on how to use your compost:
Potting Mix Lawns Trees and Shrubs
Mulch Vegetable Gardens Garden Beds
Important Health Information
Both compost and soil contain living organisms that have from time to time been associated with allergies
and illness in humans (generally people who suffer from compromised immune systems or respiratory
illness). It is therefore important to take the following precautions when handling soil or compost:
‣ Wash your hands after handling soil or compost;
‣ Protect broken skin by wearing gloves;
‣ Avoid confined spaces for handling soil or compost;
‣ Keep compost moist to prevent spores and dust problems; and
‣ Wear a facemask when handling soil or compost if you suffer from allergies or a depressed immune
system 4 .
Want more information?
For further information on home composting try your local library or try searching the internet. Here
are a few websites to get you started:
Reduce Your Rubbish:
Sustainability.govt.nz:
http://www.reducerubbish.govt.nz/
http://www.sustainability.govt.nz/
Sustainable Gardening Australia:
http://www.sgaonline.org.au/
4 http://www.resourcesmart.vic.gov.au/documents/composting_guide.pdf
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