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Composting

DIY Composting

Support Singapore’s green initiative by using your household waste to make compost. Composting can be done indoors or outdoors. For outdoor composting, place the materials in a shaded spot in your garden or in a compost bin. Be sure to cover the compost heap with a waterproof material. The compost bin can also be used for indoor composting.

There are two processes involved in composting - aerobic and anaerobic: 

Aerobic composting

Anaerobic composting

Holes are drilled in the container to allow air to circulate freely within the compost heap

Done without oxygen, in a sealed container with no holes or opening

Results in a drier and almost odourless compost, with a more neutral pH

Results in a wetter and more acidic compost, with a stronger odour


Here is how to make compost:

1) To make your own compost bin, select a container that comes with a lid. It can be made of plastic, rubber or wood. The container size is dependent on the amount of compost you wish to make. Generally, the final volume of compost will be about one-tenth of the original material used.

2) For aerobic composting, drill small holes around the bin to allow air to circulate freely.

3) Place the bin in an appropriate place such as your balcony, and rest the bin on bricks to elevate it.

4) Insert equal amounts of "browns" and "greens" into the bin (refer to the table below) and add a few handfuls of garden soil to introduce microorganisms into the mixture.


A good compost needs to have a balanced amount of "brown" and "green" components.

Browns

Greens

Fallen dry leaves and twig

Cut grass

Woody pruning

Soft green prunings

Cardboard such as boxes, cereal packets and cardboard tube

Kitchen and fruit wastes such as discarded raw vegetable parts, fruit peelings and apple cores

Wood shavings and sawdust

Teabags and tea leaves

Thick vegetable stems such as broccoli and corn stalk

Egg shells

Newspaper and waste paper

 

Shredded office waste

 

5) Add water to the mixture until it is moist, but not dripping wet. Mix thoroughly.

6) Use a shovel or garden fork to turn the pile for air circulation. Ensure that the pile is neither too wet nor too dry. If it is too wet, add more "browns" and if it is too dry, add more water.

7) You can continue to add "browns" and "greens" to the mix. Turn the pile consistently every week, and water it to ensure that it remains moist.

8) The compost mixture will heat up due to aerobic activity taking place. It is essential to let the temperature in the pile reach 70°C as the heat will eliminate any harmful bacteria in the mixture.

The finished product should be dark brown, with a soft, crumbly texture. The whole process takes between 3-6 months, depending on the materials used.


Some useful points to note:

  1. Ensure there is a mix of soft and hard materials as the latter can create spaces in the mix, improving air circulation in the pile.
  2. The decomposition process is faster if the materials used are smaller. Chop large branches into smaller pieces and shred paper before adding them into the pile.
  3. Hard carbon materials such as wood shavings and sawdust take a longer time to decompose. You should add only small amounts of these materials if you want to make compost more quickly.
  4. In aerobic composting, the small holes on the bins may attract insects and cause odours. As such, you may wish to place the container away from children and the elderly.


Materials that you should avoid putting in the compost pile are:

  1. Raw meat and fats, which decompose slowly and give off a stench
  2. Human or pet wastes, which may carry diseases and smells, attracting vermin
  3. Cooked food and dairy products as these emit odours and attract pests
  4. Diseased plant cuttings, which may contaminate the compost
  5. Glossy paper, which takes a longer time to break down and may harm microorganisms in the compost
  6. Pesticide-treated plant materials, which are harmful to compost microorganisms
  7. Charcoal ashes, which are harmful to compost microorganisms
  8. Poisonous plant material, which may contaminate the compost
Last updated on 02 February 2015

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