Monday, 3 August 2015

Making compost - it's a piece of cake

Composting is a natural process, where organic matter breaks down to create humus. In nature this happens all the time when green plant matter dies or falls from trees or shrubs, but since the middle of the last century we humans have began to understand the process of decomposition and the importance of organic matter in the soil. With rapidly reducing rainfalls, caused by climate change, compost has been found to be invaluable as it retains moisture in the soil and acts as a buffer against extreme environmental conditions.

Household waste ready to be composted

While you can be extremely technical about making compost, the non-scientist should approach the process as if they were a cook trying to make a cake. For a successful end result – be it a cake or garden compost - you need the right ingredients in the appropriate quantities as well as sufficient water, adequate air and the appropriate length of ‘cooking’. While anything that once lived can be composted its best to stick with reliable ingredients such as grass clippings, kitchen scraps, leafy garden pruning’s, shredded paper, fallen leaves and even old potting soil. The value of your compost relates to the quality of the ingredients, the position and size of the compost heap, the ambient temperature and the amount of time you spend turning the pile.

Large Gardens
For those with large gardens composting can be done on a big scale. The popular choice is to have three compost bays – or bins -placed next to each other. The bins are usually made of hard wood (ideally non-cyanide treated) and are exposed to the earth at the base below. In the first bay you place all your fresh green matter – grass clippings, garden pruning’s, fallen leaves, kitchen scraps, shredded paper and added water. After this has been in the heap for a couple of weeks it can be turned into the next bin.

The three bin system is ideal for larger gardens

The process of turning the pile mixes the ingredients and introduces air to the centre of the heap. At this stage, check to see if the mix has sufficient moisture, too dry and the compost will take ages to break down, too wet and it will become smelly. With the right mix of ingredients, as well as air and water, the heap should become hot and ‘steamy’. If this is not happening the mix requires more air and more, or less, water and perhaps some poultry droppings or manure to give it a kick-start. After a couple more weeks ‘cooking’ the second bin can be turned into the third bay. Again check moisture levels at time of turning and make sure all the heap has turned to a brown colour. Depending on how warm or cold the weather is, the compost should be ready to use in a couple of weeks. 

Small gardens
The principals of composting are roughly the same for small gardens as they are for large ones. The main difference is that you are unlikely to create enough green waste to fill three bins and even if you did you wouldn’t have the room to place them in the garden. However much you like composting, these bins are not what you want to see, especially in a small garden. Also they are best hidden away from direct summer sunlight as too much heat can kill beneficial worms, insects and bacteria.

The best solution for small gardens is to have two small size plastic compost bins. In the first bin put in your green waste; as you haven’t the mass of a large bin it’s very important that you make sure the green waste mix is varied and that moisture levels are just right. The ideal mix for a small bin are mixed layers of kitchen scraps, shredded paper, coffee grounds, grass clippings, cut up green garden pruning’s, and even human organic matter such as hair and urine (potty pee is fantastic in compost and around citrus trees).  Avoid bread, citrus, onions, meat, weeds and ‘number twos’. While all these products can be composted they can upset your bins fauna, attract vermin and possible introduce potentially poisonous diseases into your garden soil. For those who want to explore ways to compost animal poo there are well designed compost pits (advertised in specialist garden magazines) suitable for this purpose.

While not all organic materials are suitable for the small compost bin they don’t have to be chucked into the rubbish bin. In recent years most local authorities have provided a ‘green waste’ bin. This collected green waste is broken up and composted in huge scientifically controlled heaps which unlike home compost bins go to very high temperatures which kill all weed seeds and harmful bacteria. Some of these large heaps incorporate human waste (sourced from sewage plants) in the composting process. After processing, your council green waste is made into compost which is added to commercial potting mixes and other horticultural products. While we don’t get a direct financial return on the contents of this bin your community does. So when we quibble about what goes into our own garden compost systems we should make sure that kitchen waste such as citrus, egg shells, onions, pineapple tops and pumpkin seeds as well as garden weeds and twigs are not wasted by being thrown out in the rubbish bin, the correct place is the green waste bin.

Compost Made Easy
Many of us lead busy lives and we often have difficulty turning the compost heap. As regular churning is essential for a fine end result many gardeners have come up with cleaver ways to turn heaps without raising a sweat. The best way, especially for small compost heaps, is to add compost worms to the pile. Common garden worms are great recyclers but rarely venture into the warmer conditions of the compost heap. Compost worms (available from garden centres) are species which relish the warmer conditions inside the compost bin and will happily turn your green waste into humus. As they can’t live in the hottest phase of the composting process they have to have be able to escape to the earth when things get too hot. If the location of your heap avoids direct sun you will find that you can rely on your worms to do most of the turning and they will happily breed and multiply without becoming a pest.

Compost worms

The turning barrel compost bin is another easy method. Looking like an oversized tombola barrel, this bin is a large drum mounted onto a metal frame. The gardener simply adds green waste and a little water to the barrel. After closing the small entrance door, the barrel is turned by using a simple to use handle a couple of times a day. This system can produce compost in a couple of weeks in summer. Despite the expense of buying the compost barrel and frame, this method is ideal for people who want compost but don’t want to exert too much energy.

A far cheaper aid to turning conventional heaps is the compost screw. This tool is like an oversized corkscrew which you place in the middle of your compost heap. A slow turn of the handle gently incorporates the mix, bringing deeply buried green waste to the surface. Regular use of this screw-like-device along with added compost worms will reduce the need for turning your heap.

Despite the occasional setback, compost making is a fun way to recycle your green waste. Using the compost heap in tandem with your local council supplied green waste bin, can dramatically reduce your environmental footprint and will improve soil fertility in your garden.  Composting is not only a responsible thing to do it is also good exercise and mentally rewarding.

If you have a problem with your compost I suggest you read my post titled: Composting - when things go wrong

© Silas Clifford-Smith 2015

This post is an edited version of my 2009 article first published in Wellbeing magazine

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