The Composting Process
The Composting Process
Compost-making is a keystone of organic growing. One of the basic rules of organic gardening is to recycle nutrients wherever possible, and to keep inputs to a minimum. Recycling kitchen and garden waste through a compost heap meets both these requirements.
Re-using waste in this way also helps to reduce the mountains of household rubbish that must be disposed of in landfill or in other ways. This fulfils another organic tenet — to keep pollution to a minimum.
Garden compost is a rich, dark,-like material made up of decomposed plant and animal material such as weeds, vegetable scraps and animal manure. It is an excellent (and free) soil improver which can be used throughout the garden.
When added to the soil, compost feeds the teeming microscopic soil life; as a result, plant foods are made available and the soil’s health and structure are improved.
Garden compost should not be confused with sowing and potting composts, which should, perhaps, more properly be called growing media.
Why make compost?
There are several reasons why, in most cases, it is better to compost plant and animal remains rather than digging them straight back into the soil, or leaving them on the surface as a mulch.
- Uncomposted material left on the soil surface could act as a breeding ground for pests and diseases. It may also look unattractive.
- Digging in some uncomposted materials could induce nitrogen depletion.
- Composting converts soluble nutrients into a more stable form, so preventing wastage.
- Composting mixes different materials, giving a more balanced end product.
- Composting can kill weed seeds, pests and diseases.
- Composting reduces the volume of fresh material, making it easier to apply to the soil.
- In the form of compost, plant foods can be stored until they are required. This is not the case with fresh materials.
A natural process
The process of converting plant and animal waste into a useful product is not something that the gardener has invented — all plant and animal remains decay quite naturally without our interference. The key players in this decomposition process are microscopic creatures that inhabit our world. They tirelessly recycle the earth’s resources, so keeping our planet green and fertile. In the garden we refine these natural processes, making them quicker, more productive and more practical for our own needs and circumstances.
There are many different ways of making compost, all of which should succeed as long as a few basic rules are followed. The best method is the one that suits your particular requirements.
Valuable compost can be produced in as little as 2 months, or it may take a year or more; a compost heap may get so hot that it steams or it may remain cold; any weed seeds, pests and diseases that were added to the heap may or may not be killed. It all depends on the time of year, the type and quantity of material and how much time and trouble you take over it.
Ideally, compost should be fine, dark, crumbly and sweet-smelling and should contain no viable weed seeds. It may, however, be sticky, lumpy, stringy and odiferous.
The former is not difficult to produce, with a little extra effort, but the latter is still a perfectly useful compost.
The composting process
The process of converting kitchen and garden waste into compost is carried out entirely by naturally occurring organisms. When suitable materials are gathered together, these “compost workers” move in and start to feed on the more tender, juicy items. Their numbers build up rapidly, reaching 2 million per gram of moist compost in a few days, and so the rate of decomposition increases.
One result of all this activity is the production of heat, which can be quite noticeable if there is sufficient material to contain it. A large heap of mixed material can reach a temperature of 60°C (140°F) in just a few days. Weed seeds and many pests and diseases are killed, and the volume of the material decreases quite dramatically.
Compost workers need oxygen. As this becomes in short supply in the centre of an active heap, so the rate of work will slow down. Introducing more oxygen by remixing the heap will speed it up again.
If oxygen remains in short supply the process will proceed, but at a slower rate. If there is no oxygen — because the heap is too wet, for example — the material will start to putrefy rather than compost, which is not the desired result. Some moisture is essential, however; dry material will not compost.
Once the more tender ingredients have been consumed, the tougher material is worked on. The rate of decomposition slows. Heat is not produced so the larger creatures, such as worms and beetles, are safe to move in to help with the work.
By the end of the process the original ingredients of the heap will be unrecognizable. They will have been broken down, mixed together and rebuilt into what we call compost. The original volume will have decreased by at least 50 per cent.