How to compost Tested composting techniques

Learning to make your own compost is a great to recycle kitchen and garden waste to produce soil improver.

We put various techniques to the test and found two clear winners – one for the gardener who is short of time, and one for those able to devote a little more energy to producing the perfect product.

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Low-maintenance composting

Compost in six months

A man sitting down and relaxing wearing wellington boots

Turn every 2 months for decent compost in 6 months

Simply adding the right mix of green and brown materials, turning your heap once every couple of months and keeping it moist should be enough to produce decent compost.

Six months later you’ll be rewarded with a good pile of decent quality compost, with no need to apply additional products.

Verdict: Better things to do or just feeling lazy? Add equal amounts of green and brown waste little and often, and turn once every couple of months for good compost after six months.

High-maintenance composting method

Compost in two months

Advice suggests the more frequently you turn your compost heap, the faster composting happens.

Shred, mix and moisten a 50:50 mix of green and brown waste materials, fill your bin to the top and turn the contents weekly. After two months the waste materials should be unrecognisable and almost fully decomposed.

Verdict: If you can’t wait and are feeling energetic, we found that weekly turning produced good compost in only two months. You’ll need lots of waste at the start for this technique.

Added composting ingredients: are they worth it?

Lime

Added ingredient, lime - heap turned every 2 months

Adding lime didn't speed up composting

The theory: Lime, sold as garden lime or carbonate of lime, can neutralise the acidity that naturally occurs during decomposition. Organisms that aid composting work more slowly in acid conditions, so adding lime should prevent this.

Verdict: Adding lime didn’t speed up composting compared with our bin that had nothing added. It was of no benefit to compost quality.

Sulphate of ammonia

The theory: Fertilisers high in nitrogen, such as sulphate of ammonia, speed up compost production by boosting the activity of the composting organisms. However, too much can make compost acidic and slow down decomposition.

Verdict: No benefit. Compost didn’t form any quicker than in the bin with nothing added. On the plus side, the sulphate of ammonia didn’t make the compost too acidic – it had an ideal pH of 6.7.

Topsoil

Added ingredient, topsoil - heap turned every 2 months

The topsoil's weight made the heap harder to turn

The theory: Topsoil is a ready source of composting organisms such as bacteria, fungi and worms. You don’t have to wait for them to find their own way into the heap, so it should get things off to a quick start.

Verdict: No benefit. Adding two spadefuls of topsoil didn’t speed up decomposition, and the extra weight made turning the compost harder work than usual – a good alternative to the gym perhaps!

Sulphate of ammonia, topsoil and lime

The theory: Sulphate of ammonia, topsoil and lime individually speed up compost production. Putting all three to work together should make the composting process even faster.

Verdict: Less is more. Not worth the effort or the expense. The combination of additives didn’t speed up the composting process and we found the heap heavy to turn because of the added topsoil.

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