Home Composting

What is Compost?

In simple terms compost is just decomposed organic matter.  Organic matter is anything has once lived or is product of something that has lived, and when this matter comes into contact with naturally occurring micro-organisms then it starts to break down.  Finished compost is usually dark in colour, sweet smelling, moist and has the ability to store water and nutrients.

Benefits of Compost

There are three main ways that compost benefits our gardens.

1. If a broad range of organic matter is used to make the compost then it will be full of a broad range of nutrients, enabling the compost to act as a fertiliser for improved plant growth.
2. Adds organic matter to the soil which can improve the soils ability to retain moisture. Organic matter also can insulate plant roots from temperature extremes and help the soil to resist compaction from cultivation or foot traffic and provide easier passages for earthworms and plant roots
3. Finally, it adds live beneficial organisms to the soil which soil microbes and enzymes feed on.

Basically, your raw materials are divided into two groups, the nitrogen ones and the carbon ones.  You can also think of them as the green materials and the brown materials, or the moist ones and the dry ones.  Nitrogen materials are things like kitchen scraps, fresh lawn clippings, coffee grounds, etc and some examples carbon materials are hay, straw and shredded paper. In my SUBSCRIBER RESOURCES which you can access HERE I have a comprehensive list of ingredients you can and can’t add to your heap, broken up into Greens and Browns. Getting the balance of nitrogen to carbon materials is a main key to getting your heap to start “cooking”.  Research has shown that 25 to 30 parts carbon materials to 1 part nitrogen is the ideal ratio, however you definitely don’t need to be this precise.  Think of it as a guide and the closer you get the quicker your compost will break down.

Building Your Heap

Location:

If possible select a site that is level, or very slightly sloping and where you can easily get a wheel barrow to.  If you can place your heap in the shade, then that will help with moisture loss during the warmer weather.

Size:

Ideally, in order to create internal heat, your compost heap should be no smaller than one cubic metre, ie a metre high, a metre wide and a metre long.  This allows the outer layers to insulate the inside.

Bin Design: 

Using a structure to contain your heap can keep it neater and also help the compost to stay together to assist with the heating.  Any design that gives you the cubic metre dimensions will work.  My own compost system uses second hand pallets on three sides, then metre long boards along the front as that I build up as I fill the bin.  These will rot over time, however I know I can 8-10 years from them at least.  I’ve seen other ones made out of bricks, and even haybales stacked up.  Another easy system I’ve seen is a circular container made of chicken wire and held in place with star pickets, or tomato stakes.

Something to keep in mind is to allow a means of letting air into your heap.  Because I have used pallets, I can poke a rod in between the boards.  If you are using bricks, you might want to leave a few gaps in random spots.  If you can’t create gaps in your bin, insert a pole into the middle of your heap and fill around it.  Then you can remove the pole to allow air into the centre of your compost.

Adding Ingredients:

If your soil is dry, it’s a good idea to water it before you start adding ingredients.  Once the ground is wet you can start layering your raw materials.  

The size of the pieces that you add is important, the smaller they are the faster the micro-organisms will be able to work on them.  Average vegetable scraps from the kitchen are already a perfect size.  However, you may need to chop up long branches.  A garden shredder works well, or smaller branches can be run over with the lawn mower to chop them up a bit.  Often if I am adding fresh weeds or greenery from the garden, I’ll just chop them with my shovel up and down a few times!

Now start building up your layers.  Alternate between your green materials and your browns.  Build it up quite loosely as it will settle down over time itself as the materials start to break down.  Its always a good idea to make sure that your final layer is hay or straw or some other material besides kitchen waste.  Kitchen waste will attract flies, mice and other vermin, as well as some nasty odours!

You may need to add moisture to your pile.  If it is too dry it will stop decomposing.  To tell if it is moist enough, every particle needs to feel damp, but not so wet that moisture can be squeezed out if it. If it’s too wet, then the air pockets will fill up, again slowing the process.  It’s a good idea to have a means of covering your pile, so that excessive rain can run off.  I just put a sheet of tin over mine, with a brick on top to stop it blowing away.

What Next?

Ideally you will have a means of mixing your heap, and there are a number of ways to do this.  I usually wait until my heap has started to collapse a bit (shrink down in size).  This tells me that the decomposition process has started.

How long will it take? 

The amount of time needed, to get your finished compost varies greatly depending on the conditions. In warmer weather the process will be quicker (as long as the moisture levels are maintained).  Other issues such as the C:N ration and the size of the particles will also have a bearing. 

In warm weather, when the heap is turned once a week and the moisture is right, superb compost can be made in three months.  However, a heap that is full of unshredded materials and just left to its own devices can take well over 12 months.

Using Poultry:

I’m a big fan of using chickens as composters.  In fact, 90% of our kitchen scraps go in the chook-pen rather than directly onto the compost heap.  The chooks pick over the scraps, eating parts of it, scratching and breaking up other bits, and generally doing a great job of mixing it all into their bedding and manure.  This mix cannot go straight into the garden as it is too “hot” or strong in nutrients and will burn the plant roots.  However, it is the perfect mix to add to the compost heap and will break down rapidly into a lovely strong compost.

Burying organic waste:

Another method of composting, rather than using a “heap” method is to just bury your kitchen waste straight into the ground, theoretically feeding the worms and microbes right there in the garden.  This method will work, however can be a much slower process and you cannot plant into this area until the waste has decomposed.  You also need to bury the scraps quite deep, in order to prevent them being dug up by your neighbourhood dog, cat, fox, possom or rats!

Harvesting your Compost:

Once the majority of your materials have been broken down its time to start using the compost!  Completely mature compost should be well homogenised, ie all the material looks quite similar, with almost none of the original ingredients being recognised.

Compost is generally used on or near the surface of the soil.  I usually scrape over the soil with a rake or hoe and then spread the compost onto the surface.  Worms will gradually bury it.  

Using it as a mulch also works well, particularly under trees and other shade areas.  If it is to be in the direct sun, you may want to cover it with straw or some other less valuable mulch to stop the compost drying out.

The only time I will actually dig compost into my soil is if I am planting something quite deep, that will be perennial, such as a tree, or I’m establishing a new rhubarb or asparagus patch.

Well I hope that has gone some way to demystifying the compost process for you.  This has been a fairly brief overview, whole books have been written on the topic of producing “black gold”. If I’ve missed anything crucial or you’ve had issues with your compost heaps in the past, please leave me a note in the comments and I’ll do my best to address it.