Home About

Why Compost?

Jean Beetham



Composting is recycling! Composting is the natural process that converts garden and food waste into a resource that enhances the health of lawns and gardens. Adding finished compost to soil improves soil texture, helps retain moisture, reduces nutrient run-off, and naturally increases nutrient content to help sustain healthy plants. Healthier plants remove more carbon dioxide from the atmosphere and are more resistant to pests and disease. Diverting organic waste from the landfill for composting reduces the production of methane and toxic lechate that continues long after a landfill has closed.
• Anerobic (without oxygen) decomposition of organic waste produces large amounts of methane. Released directly into the atmosphere methane is more than 20 times stronger at enhancing the greenhouse effect than carbon dioxide. Aerobic (with oxygen) composting produces carbon dioxide, but not from fossil fuels!
• Up to 50% of landfill waste could be composted and returned to soils, New Zealand is losing soil at a phenomenal rate.
• Home composting also saves on energy used to run waste collection trucks, and plastic bags to collect and transport it in.
• Organic waste is a resource if composted, saving water in the garden, and reducing the need for pesticides and fertilisers, (all of which cost money), and the environment wins as well.
What is Composting?
Composting replicates the natural breakdown of organic material that creates a rich humus layer on the forest floor. A mature compost is a humus material created by combining various organic wastes in proper ratios into piles, rows, or vessels to control temperature, moisture and oxygen, and achieve accelerated decomposition. Add bulking agents (e.g. tree prunings) or manually turn as necessary, to provide aeration. The finished material is allowed to fully stabilize and mature through a curing period.
Composting is performed by soil organisms: bacteria, fungi, worms and insects that eat the organic materials.
By reproducing optimum composting conditions we can speed up the process and generate temperatures that will eliminate diseases and weed seeds. Optimum composting involves temperatures between 45-55°C, moisture content between 50-60%, and adequate oxygen for the microbes. It is complete when pile temperatures decline and remain below approximately 40°C. A subsequent curing period of 2 to 6 months is required for the compost to mature, after which it will not overheat or produce unpleasant odours during storage, and can be beneficially used.
How to Compost
Composting techniques range from passive to highly managed. A pile of foodwaste and shredded newspaper is better than not composting at all!
There are four basic ingredients needed to compost: oxygen, water, carbon and nitrogen. Carbon comes from ‘Brown’material such as wood chips, straw, dry leaves and tree prunings, or shredded newspaper and cardboard (larger amounts of paper or cardboard should be recycled), and nitrogen from ‘Green’ wet waste such as grass clippings, aged manure (avoid manure from carnivores), or fruit and vegetable scraps. The carbon provides energy for the microbes and the nitrogen provides protein. Chopping the material finely and turning regularly will speed up the process. The ideal ratio is 25 parts brown to one part green, but you can combine in roughly equal proportions and if you have these ingredients, you can compost!
• Grass clippings need to be thoroughly mixed with browns as they contain as much nitrogen as manure and can clump together and decompose anerobically producing odour. This can also be avoid by spreading them in the sun to dry before adding them to the compost.
• Meat will compost, but takes longer. If not composted correctly it will attract pests and produce odour. It should be only be composted in ideal conditions and in pest-proof vessels.
• Dairy products can be added to the centre of the pile.