The Microbe Fight Club

Home composting is simple, incredibly satisfying and can help save the planet. By Kathy Ombler.

Every year, thousands of tonnes of organic waste are dumped in New Zealand. In landfills, organic material accounts for 30 to 50 per cent of all waste.

Once in the landfill, this waste generates methane which, when released into the atmosphere, becomes a greenhouse gas about 20 times more potent than carbon dioxide.

Composting, that age-old system of nature that not only turns your food scraps, garden and other organic waste into nutrient-rich soil nourishment, also cuts the amount of organic waste going to landfills and the generation of methane.

Wellington City Council research estimates that if 50,000 city dwellings composted two kilograms of food and/or garden waste a week, up to 5200 tonnes would be diverted from its landfills annually.

Extrapolate that to all the households across the country and home composting really is a no-brainer.

The good news is that anyone can do it, whether home is a sheep station, suburban quarter-acre paradise or sixthfloor city apartment. There’s no end of advice available on how to do it. Most council websites have pages explaining the niceties of making compost and farming worms.

Don’t be put off by technical talk – of enzymes, temperature requirements and carbon/nitrogen ratios. Grant Lyon, who runs composting workshops for Wellington’s Innermost community gardens, says it’s not necessary to go into science. “The microbes don’t have a degree and they can work it out.”

There are so many ways to make compost. Choose the one that suits you, is his advice. “What system you choose should depend on the area you have, how much time you have and your budget – although major investment isn’t required to be effective.”

The quality of your compost is determined by the quality of what you put in. “Just food scraps and lawn clippings are not enough; most clippings come off poor-quality soils. There are plenty of ways of introducing nutrition, for example adding seaweed or mineral-rich gypsum.

“Most important is adding a balance between green (fresh) materials, which are high in nitrogen, and brown (dry) materials high in carbon. Healthy compost equals healthyplants, and insects and diseases generally attack poorer plants,” he says.

“The key is to cut it up, add thin layers and variety and let the microbes do the work for you. Really it’s the microbe fight club – that’s what I call the whole composting system.”

Another decision is whether to go hot or cold. Hot compost is a quicker process, with all materials added at once so the nitrogen content is high and it heats up.

After a few weeks it starts cooling and is turned to restart the heating. The heat is created by the microbes at work. Depending on how soon the compost is needed, it can be turned a third time. A cold system is exactly the same but done over time, with lower nitrogen levels so it can take up to a year to break down.

The container you use is up to you, says Grant. “Most common is the wooden pallet system; you build a square bin and fill it up. Barrels that can be turned without having to manually dig the heap can be better for some. Or you can just build a pile that you leave alone and it breaks down over time. That’s fine if you have plenty of space.”

Bokashi for apartments

Apartment dwellers can use the Japanese anaerobic fermentation system known as bokashi. Take a 10 or 15-litre bucket, throw in a handful of bokashi and add your food waste, including meat, and you’ll soon be producing quality, nutrient-rich compost.

Bokashi is a bran-based material inoculated with EM (effective micro-organisms) that ferment the organic waste.

Within weeks the fermented matter can be buried in the garden (or worm farm or compost heap) and after a few more weeks all food will have decomposed, leaving a nutrient-rich, black compost.

Most food scraps can be added. The exceptions are liquids (juices, milk and oils), paper, large bones and shellfish shells. Even if it includes fish or meat, it is airtight so doesn’tsmell, which also means it doesn’t attract flies or rodents.

A two-in-one bucket system is best to collect liquid that drains from the fermentation. This is also great for your plants (diluted) and when poured into kitchen drains and toilets thwarts odours and algae.

Bokashi is not expensive and is available from retailers. Custom-designed buckets can also be bought or you can devise your own system.

“I know a lot of people living in city apartments growing quite large gardens and getting reasonable crops using bokashi,” says Grant.