Friday, June 6, 2008

The joy of composting

Ah composting... so easy to do, yet a mystery to many.

We have a few compost systems here on our 2 acres. We have the black bins (BMW brand with lots of holes in them, little doors on each side) and large three sided compost bins. We also have another system with four star pickets and chicken wire wrapped around it.

They all work and they all provide different types of organic matter for our garden.

The big systems are great for chunky prunings and large quantities of materials. They do need turning, which requires a strong back, but they can be left for months on end and you'll still have good quality material to put around fruit and nut trees. I find the end product of these systems doesn't break down as finely as the ones in the black bins, so it is more useful around trees where it can be left for six months to slowly break down even further.

These types of large systems need to be layered with carbon and nitrogen and some additives or activators will also accelerate the process.

We add large sticks throughout the layering process which can be pulled out later - these leaves tunnels in the compost that help aerate the system.

Carbon is material such as sawdust (make sure it doesn't contain any nasty chemicals and don't apply it too thickly - it will acts as a barrier to water and air), dry leaves, straw... things that are dry and crunchy

Nitrogen is material such as fresh cuttings, fresh manures, kitchen scraps

Lawn clippings are used as a nitrogen layer when fresh, as a carbon layer when the heats has gone out of them and they are dry and brown. Use them in thin layers - too thick and they will not allow air and water to pass through.

Permaculture design includes factoring in materials for composting. For example, here in the subtropics, we have a lot of Queensland Arrowroot growing - it is a great plant and one of its many uses is it needs to be cut down annually and it makes a great compost.

Gathering materials; take the time to gather all the materials you need to make a compost of one cubic metre. This gives you the critical mass to create the heat and process to start to break the materials down.

Gather what you have - these are the types of things we put in our compost
sawdust or straw out of the chook houses
mushroom tailings from a local mushroom farm
dry leaves
lawn clippings
kitchen scraps

Process the materials - cutting up the materials into small pieces, increasing the edge, breaking down the cellular 'skin' of the plants - all helps in allowing the microbes (who will be doing the work) to get to work quicker.

Cut up materials and keep them in their piles of carbon and nitrogen

Gather some activators - you need to 'activate' your compost - these means adding things to nitrogen layers that will really get the microbes active - worm castings, manure, humus, urine, Natrakelp, molasses - all these things will get your compost going.

Then make your compost - layer by layer - add an activator to the nitrogen layer, water down the carbon layers if they are too dry.

Include chunky cuttings to allow air flow

Build it all the way to the top - aim for that critical mass of one cubic metre - do it all in one hit - this will help your compost succeed.

Cover it up - that way you control the water going in - too much rain is no good and allowing it to dry out is no good either.

Keep adding to your compost over coming weeks - include your kitchen scraps and have top up days when you get the pile up to the top again using the same alternating layering system.

Keep some carbon on hand near your compost pile to put over kitchen scraps - this helps keep flies out of it and the smell down.

You should have beautiful humus in a few months.

Recommended books.
The Rodale Book of Composting
Organic Guide to Composting (Jack Allan)
Soil Food - Jackie French
Recycle your garden - Tim Marshall

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