Cool composting – the everyday way

Let’s face it – the compost you and I make never looks as good as the stuff that comes in bags, and if it does it’s probably because it’s been left to its own devices at the bottom of the garden for three years.

The ideal crumbly black-gold produced in a six week turn-around is the stuff of text books. This kind of ‘hot’ composting requires a great deal of effort in mixing and turning, a large supply of fresh material available all in one go, and usually extra manure or bought in accelerator to reach the high temperatures needed. And mine anyway never sees this kind of attention!

But now one can rest assured that the chunky, slightly twiggy stuff us lesser mortals produce is OK.

It’s official from CAT, the Centre for Alternative Technology and font of all wisdom on things sustainable. A fact sheet entitled ‘Cool Composting, a Fresh Approach’ produced by them gives an excellent explanation for why heaps often don’t work and suggests the production of something usable (rather than perfect) in order to reduce the environmental impact of household waste and the resulting pollutant leaching from landfill sites is a worthwhile aim in itself.

And anyway, good quality compost can be made by a minimum effort continuous, even if slower, process called cool composting.

The trouble with the average household’s compost heap is that you want to add things as you go along. This includes a continuous stream of kitchen waste and then gluts of lawnmowings, piles of weeds and a weekend of prunings.

When the gluts are green and sappy, like grass cuttings or a couple of weeks of only vegetable peelings things go slimey and smelly very quickly. Or else that pile of twiggy undergrowth collected in an autumn afternoon is still there when you open the heap next summer.

This is all to do with structure. If too dense, no oxygen can reach inside and anaerobes grow, killing the good bacteria and secreting chemical substances that cause the smell. Too open, as with woody stuff, the film of water needed by the good bacteria to work on the material evaporates.

Therefore it is the combination of materials that’s crucial. ( We know that! I can hear you all saying – still bear with me) A mix of the nitrogen rich soft green stuff and carbon rich high cellulose stuff is needed and CAT call this the high fiber ‘bread and cheese’ diet!

Since we want a heap that we can add to continuously rather than storing up and making in one go (and anyway, how do you store up the green stuff without it going slimey?), we need to ensure that we have sufficient ‘bread’ going in at the same time as the ‘cheese’. We all know high cellulose leaves or twigs take ages to breakdown and this is why homemade compost is often a bit rough.

What you do instead is compost all your paper and card waste that cannot be recycled easily. By putting all your loo roll tubes, tissues, paper towels, egg boxes, scrunched up cereal boxes and food cartons (not laminated ones as this is a bit of a nuisance to pull out of the compost later but you can if you want to) into the bucket under the sink at the same time as your peelings you are premixing your heap and creating the correct open but not too open texture.

And contrary to popular opinion, CAT says that colour printed card is not harmful to the soil as the ink no longer contains the heavy metals it once did. Environmentally if you can recycle it it is best to do so, but compost the odd shaped stuff that can’t be recycled easily and you will be greatly reducing your household waste.

CAT suggests making a new heap a bit heavier on the ‘bread’ to start with to counteract the putrification tendency, and to always start a brand new heap with a layer of worm-rich compost from a previous heap (or someone else’s) rather like inoculating yoghurt with the right bacteria. If as you go along you get a glut of mowing for example, add no more than 15cm before adding a layer of scrunched newspaper or cardboard, but don’t add flat layers.

This is called ‘cool’ composting because you are adding small amounts at a time and not trying to ‘heat up’ the whole process. Hence you don’t need a bought in accelerator or high nitrogen manure but CAT says urine is OK and the contents of hoover bags contains a lot of skin and useful busy mites!

In fact what you are trying to produce is the most natural full eco-system as you can. Not only do pathogenic anaerobes halt the cycle of the natural bacteria and cause putrification, but high temperatures can also kill off or at least drive away the larger organisms. In a cooler slower heap, the heat escapes and allows a full range of decomposers to do their job. So the larger ones, who break up and eat the material provide dung to help feed the microbes. These microbes absorb the soluble nutrients and exude enzymes to chemically breakdown the material further. Middle sized organisms eat the microbes and these in turn are eaten by the larger ones. All are adding fertility to the compost!

So the only other consideration is what shape, and should it have a lid? CAT recommends a low flat shape is best for a cool heap, to avoid too much compression of the air pockets.

A separate tall, narrow heap should be made out of all your other woody garden waste, including leaves. This needs to be compacted to keep the moisture in and green weeds, old turf, mowings or any other garden waste mixed in with all the twigs, leaves and sticks to provide the damp and nitrogen rich ‘cheese’.

Leave open at the top to catch the rain. For the other heap CAT suggest either half a lid to allow the conditions suited to all kinds of organisms (some like it wetter than others) or a piece of old carpet. You need moisture but don’t want things soaking. Also a lid causes the build up of fruit flies which some people find offensive in the face when you open it up, though these are a natural part of the process and are eaten by birds.

And then you leave it for about a year. The woody ‘slow stack’ heap will have to be left for 2 or 3 years.

Obviously turning your heap will incorporate more air and increase the speed of the process, but if you think back to nature, a six months turn around is probably the most natural system. I do mix in all my waste paper as I go, but then I usually turn into another heap and incorporate other material that has built up when I’m feeling energetic.

Now thinking about it, the slow cool heap is a much more natural and least effort system and I shall sit back and relax and let nature do the whole job for me!

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About the Author

With the endless passion for organic living, I - Ann Sanders has come up with the idea of creating A Green Hand. Being the founder and editor of A Green Hand, my goal is to provide everyone with a wide range of tips about healthy lifestyle with multiform categories including gardening, health & beauty, food recipe,...