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Composting, worm farms and Bokashi bins

Published 15 April 2019
Categories:
  • Sustainability

Composting 

Composting is great for homes with a garden. Compost bins can take some food scraps and most garden waste and provide a rich, nutrient-rich fertiliser.

Why compost or worm farm?

Composting and worm farming have many benefits, including:

  • Improving soil quality by releasing rich nutrients from the compost or worm farm into the soil of your garden.
  • Preventing greenhouse gas emissions by reducing the amount of garden and kitchen waste going to landfill.
  • Reducing the use of artificial fertilisers.

How to create your own compost

  1. Find a location that is convenient to use and if possible, gets some sun.
  2. Create the first layer from twigs and sticks – this creates air pockets and allows water to drain.
  3. The next layer should be ‘green’ or ‘nitrogen rich’ materials like grass clippings or food scraps.
  4. Then alternate layers between ‘green’ and ‘brown’ (carbon rich) materials in roughly the same thickness.

Make sure you turn your compost with a garden fork weekly to aerate your compost. When you're ready to use your compost, spread it around your garden plants as a mulch, applying it up to 40mm deep.

Worm farms

Worm farms are best suited to homes with a small yard or no garden. Worm farms can only take fruit and vegetable scraps and a small amount of garden waste, and create castings/compost and a liquid fertiliser.

How to create your own worm farm

  1. Find a location in an area sheltered from rain and direct sunlight to place your worm farm.
  2. Place a layer of cardboard down on the bottom of the top tray and place your worms on top. If your worms came in a compost bedding, don’t add any extra scraps for a week or two before feeding them as they’ll eat their bedding first.
  3. Regularly feed your worms fruit and vegetable scraps - avoiding citrus peels, onion, garlic, meat, dairy, fats and oils.
  4. Harvest your worm castings by digging out a section from the worm farm and placing it on to a table in bright light. Push the material into a peaked mound and wait a minute for the worms to burrow down to the bottom to escape the light. Scrape the worm-free castings from the top and edges. Dilute casting/liquid fertiliser with water (1:10) and apply to soil.

How to use your worm compost

There are many ways to use your worm compost, including:

  • mix with water and use for watering plants
  • use as mulch (spread in a layer on top of the soil) for potted plants
  • finely sprinkle on lawns as a conditioner
  • use directly in the garden around existing plants or dug into the soil. 

Bokashi

Bokashi buckets/ fermentation systems

Bokashi buckets are suitable for homes with limited space and a garden to bury the contents. The buckets can take all kitchen scraps and they create a liquid fertiliser and a compost.

How to use a Bokashi bin 

  1. Find a convenient location as close to the kitchen as possible.
  2. Add kitchen scraps to the bucket. Mash the scraps down, and add a handful of the Bokashi mix ensuring the surface area of the food scraps are covered. Place lid back on ensuring it is completed air tight.
  3. Repeat the above step until the bucket is full. Dig a section out from your garden and bury the contents for two weeks or add to a conventional compost bin. You can plant straight in to the area or dig it up and mix it around.
  4. Drain liquid as necessary, dilute liquid with water (1:1000) and apply to soil. The liquid is safe to pour down drains and helps to clean drains by competing with harmful bacteria. 

Frequently Ask Questions - composting, worm farms and Bokashi bins

Q. Why does my compost smell?
A. Compost may smell if it is too wet, which in turn will reduce the amount of oxygen in the pile. Aerate your compost by turning it and add some dry materials like cardboard, dry grass clippings, twigs and sticks or straw.

Q. Why isn’t my compost breaking down?
A. This is usually because there’s not enough air or active ingredients. Turn the compost, add some water and manure.

Q. What can I do about vermin?
A. Remove any breads or grains, add some water, turn the pile and if still an issue cover entry with chicken wire.

Q. Why are there little flies everywhere?
A. These little flies are most probably Vinegar Flies (or Barflies) and are attracted to over-ripened fruit and vegetables. Vinegar Flies are not a serious problem, but can be avoided by frequently turning your compost pile; adding some dry materials; adding lime; or covering the ‘green’ layer in your compost with soil. If they are near your worm farm, cover the top layer of with soil, or by adding wood ash, crushed egg shells, or lime.

Q. When do I harvest my worm farm?
A. When there is little or no original bedding visible in the bin and the contents are brown and earthy looking worm castings.

Q. What do I do with my worm farm if I’m going on holidays?
A. Fill a third of a tray with fruit and vegetable scraps and shredded newspaper. This will feed worms for four weeks.

Q. Why does my Bokashi bin smell bad?
A. This is usually because the liquid hasn’t been drained or there’s not enough Bokashi mix being used. Drain off the liquid to make sure it’s not backing up and add a little bit more Bokashi mix each time you add food waste

Q. What do I do with my Bokashi bucket if I’m going on holidays?
A. It’s best to bury the contents and empty the system if you’re going away for more than a week as the liquid can back up in to the bucket and cause a strong smell.

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