How to: Make your own compost bin
If you're serious about gardening, a compost heap is a must. Aaron Shirriffs has some tips on building a tidy bin to turn waste into garden goodness.
What do I need?
While there is an untold number of ways to build your own compost bin, this is a simple method to make a 1m x 1m bin. You'll need 20 1-metre lengths of 150x50mm timber, four 1.2m 100x100mm posts, and galvanised nails. You'll need additional wood and nails if you make a lid (ideally, compost bins should be covered to prevent rain cooling them down). You might also consider adding a removable front (this helps greatly when you want to remove the finished compost) but it will depend on how complex you would like to go.
Where should it go?
There are no hard and fast rules for the location, but the rule of thumb is to have it near where you are going to use it (eg, the vegetable garden). It is important that the area is well drained and draws moisture away from the bottom of the bins – otherwise it will become soggy and that slows down the compost process greatly. Keeping it out of sight and away from the ntsG living and sleeping areas of the ntehouse is a wise move.
How do I build it?
The posts will be placed in a 1x1m square and clad with the planks – five for each side – to form the box frame. Space the planks 50mm apart, to help with the airflow through the compost. You'll be left with 200mm of the posts to bed into the ground, making the box 1m high.
Ideally you should have three bins; one that you are putting material into, one that is in the process of composting, and one that is finished and ready for use. As they cycle through, each box's purpose changes.
A lid is recommended for each bin. You can make a simple one by butting together seven more 150x50mm planks (also 1m long) and nailing them together with another two planks running parallel across the top.
How do I maintain my compost?
Keep the pile dry – the materials going into it will create moisture and, because it is a heating process, you need as little sogginess as possible. If you find that your compost bin is wet and soggy, try to add dry carbon-based materials such as dry leaves, untreated sawdust or dry lawn clippings. Be careful not to add vast amounts, because carbon based materials take longer to break down, but small amounts will help dry out your pile. Likewise, aeration is critical – you should regularly turn your compost pile.
What should and shouldn't I put in the bins?
The majority of organic waste material from your kitchen can go into the compost bin. But you shouldn't use bread, meat, or milk products as these tend to attract pests and rot down badly. Rice should be avoided – cooked rice can produce dangerous bacteria and raw rice can attract vermin. Most nut products are fine, but walnuts produce juglone which can be toxic to other plants. Newspaper is fine but not processed paper (such as in magazines and brochures) as the coatings don't break down. And don't put human or animal waste in the compost – it's a health hazard.
Compost bins generally shouldn't smell horrible. They have a bit of an odour, due to it being a rotting/decomposition process, but if it smells very pungent or awful then you should revisit what you are putting in there.
And the end result?
The end product will ideally be a dark, loose material that doesn't smell strongly and isn't gluggy or soggy. It has to be dug into the garden soil; don't plant anything directly into it as this can burn the plants you're trying to grow.
Aaron Shirriffs is from the Outerlife Group. Article courtesy of builderscrack.co.nz.