EM composting

Effective Micro-organism (EM) composting is a bucket system that uses micro-organisms to break down food scraps into a compost and liquid fertiliser, which you can then use in your garden. Technically it is not composting but a form of fermentation. It is the most effective alternative to composting food scraps for people who lack space.

EM is a powder-like substance that contains micro-organisms that breakdown food scraps.

How to go about EM composting

• A two bucket system is needed – one nested on top of the other. The top one needs an airtight lid and holes in the base to drain into the lower bucket.
• Buy some EM powder
• Store your EM bucket system in a warm, dry place out of direct sunlight, such as a kitchen cupboard.
• Sprinkle a little EM powder in the bottom of the upper bucket.
• Place food or meat scraps in the bucket then coat them evenly with more EM powder. Break up the big pieces to assist fermentation.
• Use about one handful of EM powder to every 3-4 cm of food. Use more when adding high protein foods such as meat, eggs, cheese and fish.
• Press down on the material every time you add more food scraps to remove air.
• Try to keep the food scraps as dry as possible. Any excess moisture can cause them to smell.
• Close the lid tightly every time you add to the bucket. It needs to be airtight to work properly.
• Repeat layering until the upper bucket is full, then top up with a generous coat of EM powder.
• Store the bucket system away from direct sunlight for at least 48 hours, or preferably 7-10 days in summer and 10-14 days in winter.
• Drain the liquid frequently from the lower bucket during the fermentation period.
• Your compost is now ready to be used.

Using the bucket compost

Dig a hole or trench about one spade’s depth in your garden, add the compost, mix with soil and then cover. The compost will supply your plants with food and your soil with the useful microbes.

You can also use the compost around trees by digging holes about a spade’s depth at 60 cm intervals around the tree drip line.

Warning! Be sure that plant roots do not come in direct contact with the compost, as this may burn plant roots. This is because the EM compost process is acidic when first dug in but neutralises after 7-10 days.

Ensure the bucket is washed thoroughly at the end of each batch.

Using the liquid

The amount of the liquid drained will depend on the food scraps in the bucket. Fruit and vegetables tend to release more liquid than other foods. Don’t be concerned if little or no liquid is produced.

The liquid can be used to fertilise the garden or house plants - use a teaspoon to 2-3 litres of water and apply directly to soil. Do not apply directly to foliage.

The liquid can also control odours and prevent algae build up around the house. Pour the concentrated liquid directly into kitchen and bathroom drains, toilets or septic system.

The EM bucket juice cannot be stored - use it within 24 hours of collecting.

What can be added to your EM compost bin?

• Fresh fruit and vegetables
• Cooked and uncooked meats and fish
• Cheese and eggs
• Bread, coffee grounds, tea bags etc
• Flowers
• Tissue paper

Do not add to your EM compost

• Liquids, such as milk, orange juice and oils
• Paper and plastic wrap
• Meat bones

Successful EM composting

EM composting works by fermentation. The food looks preserved like pickles when the process is complete. If the bucket smells similar to pickles or cider vinegar, the composting has been a success. Occasionally, over longer fermentation periods, a white cotton-like fungus may appear on the surface. This shows that fermentation process has gone well.

Unsuccessful EM composting

A strong rancid or rotten smell indicates a poor batch of compost. A Black or blue-green fungus indicates that contamination has occurred and the rubbish has rotted instead of fermenting.

Reasons for failure include:

• Not adding enough EM powder
• Not replacing the container lid tightly after every use
• Not draining the EM bucket juice frequently from the bucket
• Prolonged exposure to direct sunlight or extreme temperatures (too hot or cold)

To get rid of a batch of poor compost, find a spot in the garden, a good distance from plants, and dig a hole about one spade deep. Place three handfuls of EM powder into the bottom of the hole. Tip in the poor batch of compost and mix with some soil. Sprinkle another three handfuls of EM powder onto it and fill the hole back in with soil.

More information on EM composting can be found in the Christchurch City Council website’s rubbish, recycling and composting section.