Great changes take place within a compost pile so that it becomes greater than the sum of its parts – there are more usable nitrates than in the original material. “Good micro-organisms in the finished compost protect and nurture plants
Composting can be anaerobic or aerobic and be made as a batch or continuously.
Anaerobic compost is made without air. It is produced in a closed system, perhaps in a plastic bag or a sealed bin and usually takes longer than the other. It does smell but as it is sealed, no smell is noticed. The main advantage is that no nitrogen is lost.
Aerobic compost is produced when oxygen is encouraged into the system. Within the first week of a pile being constructed, it will heat up to about 38 degrees Celsius as the material oxidises.
There are four stages in a compost pile. The first, the mesophilic phase, is the heating up when burgeoning bacteria raise the temperature to about 40 degrees Celsius. Many pathogens and bacteria dangerous to human heath are destroyed as the next stage, the thermophilic, begins.
Within the pile, thermophilic bacteria begin the work of breaking down the organic material, attacking the organic matter vigorously and creating heat.
As the pile cools micro-organisms that moved out during the heating phase re-invade and work on the pile, digesting the now softened material. Insects and fungi invade and dying, create more nitrogen that is used by the next invading army.
Easily available soft matter has been digested, but coarser material remains although the hard outside has been broken down. Larger fungi as well as fauna such as beetles and earthworms also help digest the harder material.
The fungi coat the plant matter and invade it while digesting the nutrients. In turn the fungi are digested by other aerobic bacteria which also penetrate plant cells further breaking them down.
The final stage, the curing stage, is when the almost finished – much shrunken – compost rests while the final and slow decomposition takes place.
It is important that it is not still working so that the nitrates become available to the soil immediately. There is controversy as to how long the total process takes: some say a month, some three months, yet others believe a year should pass.
If there is little or no coarse material left, if the compost smells sweet, and if it feels springy and pliable – use it.
Batch composting is when the process described above happens in a pile made at the one time from materials gathered for the purpose.
Continuous composting is most likely to be convenient to the householder who wants to put out food scraps and garden wastes as they occur. Continuous composting is convenient and sensible.
A continuous compost is an aerobic pile in which all stages could be happening at once. The top layer – the freshest – may be hot while the bottom is curing.
A three bin method is suitable. Each bin is about a meter square and a meter high. In the bottom place some sticks to allow air though and on top of this put a layer of leaves or similar.
Then add scraps and waste as you like. If the pile begins to get slimy through too many kitchen scraps, cover with a layer of plant matter or a little soil. When the pile is full – this may take months – leave it to cure and begin a new one.
When the first has shrunk to about one third, open and use.
Soil organisms: macro and micro fauna, flora and fungi; living, eating and dying; change the nature of the original material into a pliable sweet smelling humus that is the perfect soil additive.