The following section describes the easiest ways to make fertilizer using anaerobic decomposition. This type of compost "thrives on neglect". These broad categories approximately describe most home grown anaerobic composting methods:
Closed or sealed method: Use a sealed plastic container (bag or bucket/box): put your organic waste in it and leave
for a year, totally sealed. Do not take a peep. I've read on the web about this method but have not tried it with kitchen waste.
Semi sealed: (sand or water covering) dig a trench, fill with organic waste and cover with soil. The trench of buried organics (newspaper, kitchen waste, branches, even old tins and more) to make garden fertilizer has been applied with great success by Abalimi Bezekhaya, a Catholic Welfare NGO that teaches gardening to previously unemployed women who live on top of the deep sand found in most of Cape Town . The Cape Flats, or greater Cape Town was once under a shallow sea, and is basically dune land with small seasonal marshes. My soil in Goodwood belongs to this system and I've also tried the trench method with success.
or: Make a perforated bucket, embed it in soil, fill it with organic waste and put a lid on it.
A partially anaerobic method of composting that thrives without the digging over needed for a hot heap, is to saturate a normal compost pile with water and cover it with a waterproof sheet. If it gets slimy and smelly this is good, say my sources.
For water immersion: put the organic material in a bucket of water. According to my source on the web, leave it for a year. Oxygen will enter the water in this method, so there will be some aerobic processing taking place at the same time as the anaerobic. The deeper the water, and less disturbed, the less this will be.
A traditional immersion method was used in the rice paddies of China for millennia. A trench near the paddy
would be filled with organic waste including green manure, old rice straw and animal manure, mixed with sediment (probably inoculates the material) covered with water, and a year later, when liquified, distributed over the rice fields. While a farming rather than garden fertilizer, if this method of recycling in situ on the same land worked for centuries to keep soil fertile, similar principles can apply in your garden.
Most of the home grown anaerobic processes for making garden fertilizer fit into these categories, so adapt them to your own needs and circumstances. To create a truly anaerobic environment, one should never open the vessel. Be aware that during maturation, methane will be produced and released into the atmosphere and you will be liberating one of the most potent greenhouse gases. A more nitrogen rich compost can be produced with anaerobic composting, and pathogens will not necessarily be wiped out by heat, as in the aerobic process of hot composting, but they will be hugely reduced by competition with more beneficial organisms.
The processes described above are rarely purely anaerobic or aerobic, because oxygen will leak into the containers, and there is dissolved oxygen in water. However if any aerobic activity occurs it will quickly deplete this oxygen, making oxygen a very scarce resource in the circumstances. However, intentionally mixed aerobic / anaerobic composting can also be used, and I'll describe this on another page.
Sometimes I throw out the rule book on C : N ratios and just do my own thing. I steep dry brown garden waste in urine.
Fill a bucket with finely shredded material. I use sweepings of the tiny leaves from under my acacia tree. Top up slowly to the bucket edge with urine. My source is undisclosed but essentially animal like all other types. Let it stand for a week. An intense anaerobic brewing would have started. Then empty the bucket on the unplanted soil in a bed being prepared for heavy feeders. The horrendously smelly mush will stop smelling within a few hours and shrink down to fine black compost in record time. I still need to work out when it
can be safely planted, and what environmental impact it would have if widely applied.
My understanding of anaerobic composting science gained from reading, will follow and an article on commercial anaerobic processing. A full description of how to use a mixed anaerobic - aerobic process on garden weeds to make "Jauche" or liquid green fertilizer is described here.
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