Organic matter and composting

Organic matter

What are the three most important ingredients in French baking? Butter, butter and butter. What are the three most important ingredients in organic growing? OM, OM, OM. What do we mean by organic matter? Well, just about anything that was once a plant or an animal by- product: leaves, grass clippings, seaweed, green manure, animal manure, scrapings from the chookhouse, peastraw, old cardboard, the dirt from the bottom of your drain...By adding OM you're achieving several very important things: encouraging worms, adding structure to the soil, adding nitrogen and various compounds and elements, providing a habitat for microorganisms- the list goes on. What you use will depend on what's available around you. The trick is to make the most of what you can get and don't be afraid to think outside the square.

Some considerations: - Most OM is acidic, so add a little lime (dolomite if possible) with it. - Think about how potent your matter is, for example chicken manure is very strong so use it sparingly and mix it with other stuff (i.e. compost). - Bear in mind it's provenance, for example horse manure from a racetrack is likely to have antibiotics in it, so let it mature for a few weeks before using it. Seaweed will need the salt rinsed off it with a hose. Some types of OM can be dug in, for example chopped up seaweed, some is better as a mulch.


Well made compost is the single best addition to an organic garden. There are different ways to make compost but they all come down to the principle of alternating layers of different kinds of organic matter. The idea is to use layers to achieve airflow so that the composting process is aerobic. For example I would start with some fibrous material such as small twigs, brocoli stalks, old cut flowers. Then add a layer of green (nitrogen- rich) matter such as vegetable scraps or lawn clippings. Then some random stuff- bits of seaweed, old yoghurt or other food from the back of the fridge, even a bit of cardboard. Then start the layers again. It doesn't need to be perfect, and it doesn't matter whether you use a big bin or just a pile, just make sure you've got layers so it can breathe. It's a good idea to cover the heap to keep in the heat and to stop it getting waterlogged.

And, as always, experiment- try layers of different things. You'll notice temperature makes a difference. In Waikanae a summer heap will make compost in 8 weeks, in winter double that. When ready it should be more or less dark brown and crumbly, again it doesn't have to look like commercial compost- lumps and bumps are fine as long as most of it has broken down.

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