Waste sustainability through composting

Of the four sustainability issues we individually can do something about (energy, food, waste, water), there is one that almost everyone can take action on today and every day.

So easy it is to put your domestic waste in to the rubbish bin each week and see it disappear. Out of sight and out of mind? No, not at all! And nor should it be.

We see our rubbish dumps growing from the unwanted detritus of a consumer society. We smell decaying organic matter as it putrefies away. We hear the big trucks transporting huge quantities of waste around the city and country side.

In 2010, Aucklanders sent over one million tonnes of waste to landfill with around 20% of that being organic waste that could have been diverted from landfill sites.

To enable that diversion, Auckland Council initiated a waste minimisation program that aims to avoid the social, environmental and economic impacts of excess waste.

A major part of that initiative is the composting of domestic organic waste streams as a simple way to divert waste from landfill.

Easy composting method makes for an easy sustainable waste management process.

Composting at home is one part of that program.

Why make compost?

Composting your kitchen and garden wastes turns the nutrients, minerals and organic matter in those wastes, in to a resource for your garden.

The first reason to make compost is that it saves you money by retaining soil moisture levels and avoiding the need to apply fertilisers. Compost replaces the soil nutrients and minerals depleted when crops are harvested and adds organic matter to the soil.

It also sequesters atmospheric carbon in the soil, reducing the release of carbon dioxide and methane gases from landfill to the atmosphere. So the second reason to compost, is the reduction in greenhouse gas emissions that contribute to global warming and hence, climate change.

Who can compost?

Anyone can – just choose a system that is appropriate to your site, your waste types and the amount of waste you create.

Those with a garden and sufficient volumes of waste can install a compost bin to manufacture a beneficial garden resource. A worm farm that converts the same range of wastes to vermicast is better suited to smaller gardens or those with small waste volumes. For those living in an apartment without access to a garden, a Bokashi system achieves the same result – the conversion of wastes to a useful resource.

When to compost?

All the time. Year round, your composted kitchen and garden wastes are an accumulating resource that will save you money.

What to compost?

It is easier to define what not to compost than it is to list what can be composted.

Don’t compost meat, bones and fish scraps as these may attract pests that you do not want around the garden. The Bokashi composting system can handle these scraps but I find there is too much competition for kitchen scraps to use this system. Those who live in an apartment where access to a garden is not easy, will find the Bokashi system ideal for all of their kitchen wastes.

Inadvertently spreading pests and diseases around your garden can be avoided if diseased plants and the seed heads of perennial weeds are not added to the compost. Likewise manures from your domestic pets (dogs and cats mainly) are best not added to compost, especially if the compost is to be applied to food crops.

Foods that may contain pesticide residues, for example banana skins, or are allelopathic, are best kept out of the compost. Allelopathic crops (for example black walnut leaves) exudes chemicals that inhibit germination or growth of other organisms).

Finally, petroleum based machine oil or chain oil ought be avoided.

Otherwise, compost everything, including small amounts of paper and cardboard.

How to compost

Instructions on purchasing or creating your own bin compost, worm farm or Bokashi system can be found at our household composting page.

Composting has so many advantages that it is an integral part of our communal food gardens project.

3 thoughts on “Waste sustainability through composting

  1. Thank you Jim. The scale of the task for each of us to attain sustainability in each of these four areas is large.

    For example. if our individual CO2e emissions is around 10 tonnes per year, to scale that back by 10% say (i.e. 1,000 kg CO2e/year), then we would need to individually reduce our organic waste volumes going to landfill by 526 kg per year or 10 kg per week. That is a simplistic view of the issues, and of course, scaling waste back by that amount is not going to happen, but it does serve to indicate the scale of the task before us.

    To achieve the same reduction in emissions, the driver of a small car (consuming 6 L petrol/100km) would need to reduce their annual mileage by 7,042 km. On the average, that represents around a 30% reduction in miles travelled each year.

    Or consider our electricity use – a household would need to cut electricity use by around 7,246 KWh per year to achieve the same CO2e reduction. The assumed average household electricity consumption is 8,000 KWh/year!

    Perhaps reducing emissions in each of these area by ⅓rd of the amounts noted above would be sufficient to achieve that 1,000 kg CO2e reduction per year. But that is only for a 10% overall reduction, as a nation, we need to aspire to a 40% reduction on 1990 levels to do what science tells us needs to be done.

    The only way forward I see, is for us each to stop buying stuff we do not need, PLUS to start taking carbon out of the atmosphere (ie sequester carbon via biochar).

    I am preparing an article along these lines for publishing in a couple of weeks, but do you see the scale of our global warming issue?


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