Helen Babbs explains the original layered compost heap method.

In August, the first batch of vegetable crops finish and the lush summer growth around the smallholding starts to need cutting back. Composting will turn the piles of long, cut grass and bolted lettuces into rich organic matter to feed the soil next year. With all that needs doing at this time of year, it’s tempting to simply throw it all in a pile or compost bin, but a random pile like this will rot down into poor quality compost, full of lumps and dry, unrotted patches. There are various “compost activator” mixtures available to be watered on to your heap, or patent compost makers supposed to take the effort out of turning and mixing the heap. However, I’ve found the quickest and easiest way to get great compost every time is to go back to basics, and follow the original layered compost heap method developed by the pioneers of organic growing in the 1920s.

Equipment and ingredients

A layered compost heap can be made in a bin, or as a free-standing stack.  I find it easiest to work with a bin, as I don’t then have to worry about keeping the sides neat. 

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The bin doesn’t need to be fancy: four pallets tied together in a square with bale twine works very well, and makes a convenient size for filling.  If the pallets are very open and your compost material is quite small stuff, such as kitchen scraps or lawn mowings, you can line the sides with flattened cardboard boxes that will rot down along with the heap. Apart from the compost bin, the only other equipment you will need is a site for your bin, ideally on the soil not concrete, and an old fence post or other pole, as tall as the height of your bin. 

In addition to the green material, a layered compost heap also needs some strawy manure, some soil or finished compost and some powdered garden lime or wood ash. Although a layered heap can be built a bit at a time, I find it’s easiest to collect up a good supply of composting material for a couple of days beforehand, storing it in plastic sacks or a separate loose pile.

The first four layers

The compost heap starts with a 15cm layer of vegetation – the “green layer” – to cover the entire base of the bin. 

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Onto this is spread a 5cm layer of strawy manure, ideally as fresh and unrotted as possible. If you don’t have any from your own livestock, most horse-owners will be happy to let you have some – unrotted manure is usually the hard kind to get rid of! Chicken manure, along with the bedding, with also do for this layer, or even simply a layer of fresh straw or crumpled paper, as the whole purpose of this “brown layer” is to add open, high-carbon material to balance the thicker green layer below it.

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Onto these two thicker layers is spread a 2cm layer of soil or ready-rotted compost. While it might seem a waste to be putting good soil or finished compost back into a compost heap, this provides a large supply of bacteria to get the new heap rotting down quickly. If you have some poor, lumpy compost to use up, this will rot down finely on a second chance. I find it’s also a handy way to deal with mole hills, as a couple of large ones can be quickly scooped up to make a complete “soil layer.”

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With the soil covering the straw, it’s time to water the heap well, putting enough water on to soak into the bottom green layer. Finally, the top of the heap is sprinkled with a thin dusting of lime, wood ash or seaweed meal. 

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The best composting bacteria prefer a neutral pH, so the lime keeps the heap rotting fast by stopping it getting too acidic.

Compost chimney

Once there’s a layer of material across the bottom of the bin to hold it up, the pole is driven into the centre of the heap. 

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This remains in the heap until it’s finished, and is then pulled out to leave a central “chimney,” allowing air to penetrate to the centre of the heap, and the heat produced by the rotting vegetation to escape. The compost bacteria thus don’t get suffocated for lack of oxygen, or scorched by the rising temperatures. For a small heap, up to about 1m across, only one central pole is needed, but if you’re building a larger heap, you’ll need to have an extra chimney for every 1m width.

Layer on layer

With the central pole in place, the next 15cm green layer is added on top of the lime layer, and the whole process repeated until the bin is full, or a free-standing stack is as high as you want it. 

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This sequence of layers might sound complex, but it very quickly becomes a rhythm, whether you’re building all in one go or adding layers over several days or even weeks. It’s a good idea to wobble the central pole about a bit as the heap gets higher, so it doesn’t get too firmly fixed down.

The finished heap

When the heap has filled up to the top of the bin, it’s finished with a slightly thicker layer of soil and lime, and the pole then pulled out. A few clods of soil or stray leaves may fall down the hole, but it should be left largely open, and will already start to feel warm within it. As the heap warms up and starts to rot, steam will be seen rising from the chimney hole within a few days!

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At first, the heap will drop rapidly, eventually settling at less than half its original height. No further work is needed, apart from to pull any stray weeds from the top layer of soil. After about 12 weeks or less in the summer, the compost will be ready. The top of the heap will have a thin layer of coarse compost, still with some sticks and lumps, but underneath is fine, black, soil-like compost, ready to use anywhere about the smallholding. 

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There is only one word of warning for layered composting – when it works this well, composting can become a bit addictive, and you will never look at a pile of weeds in the same way again!

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Helen Babbs wrote this article exclusively for Smallholder magazine. For more like it subscribe here, call 01778 392011 or email subscriptions@warnersgroup.co.uk or buy a copy from your local newsagent.