Between 60 - 70% of household waste is compostable materials in the form of food waste, garden materials, food contaminated paper, tissues and handtowels.

Definition of compost

  • A mixture of organic residues such as decomposed vegetation, manure etc, used as a fertiliser.
  • Organic waste is derived from living organisms, both animal and plant. It may include garden and food wastes, manure, sewerage and natural fibres such as paper, cotton etc.
  • Compost is a natural soil conditioner made from organic waste. The material is from plant and animal origin, mixed together to hasten the process of decay. It is ready to use when the original material is unidentifiable. It has a dark brown, crumbly texture and pleasant earthy odour.

Way back when...the history of compost

One of the earliest references to compost appears in a set of clay tablets found in the Mesopotamian Valley about 2500 years ago.  Other references occur in literature throughout medieval and modern times.  In recent times, Sir Howard researched and wrote extensively about compost, and is recognised as the father of modern organic farming.

Composting is something that has happened naturally ever since vegetation first covered the earth. The leftovers of one process became the inputs for growth and rejuvenation in another process. At some time in the distant past, humans noticed that plants grew better near piles of rotting vegetation and manure, and this information was passed on to future generations.

The importance of healthy soil

In 1937, US President, Franklin Roosevelt said: “The nation that destroys its soil, destroys itself.”

This sentiment is echoed in the motto of The New Zealand Soil and Health Association 

Healthy Soil - Healthy Food - Healthy  People
Oranga nuku - Oranga kai - Oranga tangata

The importance of soil organic matter is outlined in an article by the Food and Agriculture Organisation of the United Nations.  

in Over 80% of the agricultural soils in the developed world contain only 1-3% of organic matter. For a good, strong soil to grow healthy food, it must contain at least 6-10% of organic matter.   

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The Canterbury region has topsoil ranging from only 10cm deep to 40cm deep. We can return organic matter to the topsoil by composting, and thereby bring about all the benefits of using compost.  

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Digging up the facts about dirt

Dirt, dust, soil, topsoil, earth, sod, ground, turf, 

The material we call soil is a complex mixture of eroded rock, mineral nutrients, decaying organic matter, water, air and billions of living organisms, most of them microscopic decomposers. Although soil is potentially a renewable resource, it is produced very, very slowly by the weathering of rock, the deposit of sediments by erosion and the decomposition of dead organisms. Soils develop and mature so slowly that it takes between 200 and 1000 years to develop 25mm of topsoil. According to a 1990 survey, topsoil is eroding faster than it is formed on over 1/3 of the world’s cropland.

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Compost ticks all the boxes

  • Improves soil quality
  • Increases productivity
  • Reduces water use
  • Reduces pesticide and fertiliser use
  • Reduces nutrient run-off
  • Reduces soil erosion
  • Supplies the calcium, phosphorous, lime, nitrogen and potassium needed for plant growth
  • Improves drainage in heavy clay soil and conserves water in light sandy soil
  • Keeps the soil cooler in summer and warmer in winter
  • Increases aeration in compacted soil
  • Promotes root growth and creates spaces in the soil for air and water
  • Saves landfill space
  • Reduces the need to transport your greenwaste to the dump
  • The amount of water pollution, gas release and odour from landfill is decreased

Making black gold - how to compost

Otherwise, buy commercial bins online or from hardware stores.  

  • Earthmaker's patented three-stage process uses traditional three-bin composting but stacked vertically so gravity does the hard work!
  • Black bins, tumblers and other composting accessories available from:

Four ingredients compost recipe 

For a well-functioning compost heap you will need:

  • Micro-organisms: Compost is made by billions of microbes that digest the food you provide for them. All this microbial activity will make the compost heap hot. To function, the microbes need oxygen, water  and food.
  • Air: Create air tunnels in your heap by poking sticks through it, or by turning the pile, by breaking up any clumps of compost, or by adding compost worms, who will make their own air tunnels.
  • Water: An ideal heap contains as much water as a wrung out sponge – damp and moist, not wet. A dry compost heap will die, as will one which is too wet, which makes the heap heavy and squashes the air out of it. If you are using kitchen as well as garden waste in your heap, there should be enough moisture in the leftover fruit, animal and vegetable materials to keep the heap balanced.
  • Food: Compost needs both ‘brown’ (carbon) and ‘green’ (nitrogen) food to work properly. Browns (carbon) are generally dried materials like autumn leaves, straw, dead weeds, twigs and branches, wood chips, wood ash and sawdust and paper and paperboard products. Greens (nitrogen) are fresh plant materials like fruit and vegetable scraps, other food waste, grass cuttings, weeds and other plant matter.

Variety is the spice of life

Try mixing up your food ingredients layering "brown" and "green" materials in a bin.

  • Food scraps
  • Garden prunings, weeds and grass
  • Vacuum dust – contains dust, hair, nails, skin cells…
  • Pencil sharpenings
  • Cork
  • Paper products
  • Natural fabrics – wool, cotton, silk

Composting is a biological process, and a compost pile is really a teeming microbial farm. There are more living organisms in a teaspoon of good compost than there are beings on the earth. Creation of heat cooks the materials into compost. Once a heap has been built, billions of creatures will create the necessary heat to begin the process. Weed seeds and pathogens should be killed if the heap stays at around 55 – 60 degrees C for 5 – 7 days. Bacteria start the compost making process of organic matter breakdown. Populations of fungi, protozoans and round worms then increase, while insects, beetles and other animals follow later. 

“There are only two truly creative things human beings can do: make babies and make compost” (Anon) 

Using compost: 

Compost is ready to use when it has turned dark brown and gone crumbly, with a smell like the heart of a forest. If used too soon, the compost may borrow nitrogen from the soil to finish breaking down, which will reduce the amount of nitrogen available to growing plants.

Do not pile compost up against tree trunks or plant stems as this may lead to fungal decay, - the stems and trunks need air to circulate. Do not put compost at the bottom of the hole when planting trees or shrubs – rather mix it with equal parts of topsoil.

Partly decayed compost can be used as a mulch, but do not dig it in deeper than 15cm or hydrogen sulphide gas will be created, which is toxic to plant roots.

There can never be too much compost!

Make compost ‘tea’ by filling a cloth bag with a litre of compost. Tie the bag and soak in a bucket of water. Let it ‘steep’ overnight and then pour around soil of plants. If you leave the tea longer than overnight, make sure you dilute it with equal parts of water before pouring.

Compost poem (By an Earthworks graduate.) -need link

Is your soil sad and lacking in life? Your trees in trouble, your plants in strife?
You could add water and cow manure. But compost is a better cure.

Start off with leaves and bits of stick. Begin in layers and not too thick.
Now add manure to the compost heap. It may be chicken, or horse, or sheep.

There are tonnes of things you could have in there. Like vacuum dust and human hair.
And grass and leaves and bits of tree. And seaweed if you live by the sea.

And fruit and veggie peels and rinds. And other things which you may find.
With blood and bone and a bit of lime. Your heap will have a lovely time.

Layers breaking down and rotting away. Compost is ready to live another day.
It must have air and must drain well. And kept like this it will not smell.

Worms work and slave and breed and toil. Chomping scraps and making soil.

Facts and figures -need links

  • An acre of good, living soil can contain 900 pounds of earthworms, 2400 pounds of fungi, 1500 pounds of bacteria, 133 pounds of protozoa, 890 pounds of arthropods and algae. They are sometimes called the ‘micro herd’ – the most important livestock on any farm.
  • Figure out what's on your "quarter acre".
  • Regular use of quality compost has shown yield increases of up to 15% for lettuce and broccoli; irrigation water savings of 10% in summer on sandy soil; significant fertiliser savings, faster maturation of crop and more even crop quality.
  • Biologically active soils are less likely to support disease-making organisms. Compost has been shown to contain certain microorganisms that can suppress or kill disease-causing organisms such as root rots and nematodes.
  • Farm compost trials in Australia show that improved organic matter levels resulted in positive effects on moisture holding capacity, bulk density, cation exchange capacity, pH and reduced erosion. The trials also showed that marketable yields for a wide range of crops were improved, especially after repeat applications of good quality compost.
  • Research indicates that for every 1 acre of land which we bring back to a 6% level of organic matter, we would be sucking up to 12 tonnes of greenhouse gases out of the atmosphere and into the soil. Any composting has a positive effect on reversing the volume of greenhouse gases in the atmosphere. (Peter W. Rutherford & Mary Lou Lamonda: The Australian worm and compost Book,1994.)

Composting Websites: