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Why start Composting?

So to start, here is a little bit of education from the researchers in waste management collated by the Brisbane City Council and Oz Harvest on the associated costs with food waste in Australia.

  • ~4 million tonnes of food waste ends up in landfill each year, costing our economy an estimated $20 billion each year (1)
  • As food waste breaks down it emits Carbon Dioxide and Methane, a gas ~25x more potent the Carbon Dioxide. 1kg of food waste generates ~1.9kg of CO2 (2). That's ~8 million tonnes of CO2 being emitted from food decaying in landfill in Australia.
  • More than 31% of the average Brisbane households bins is food waste, adding up to $3,800 in extra costs every year for the average household (3)

Composting is able to reduce nearly all organic material down into a useable soil medium heavily sort after by gardeners worldwide. While the process of composting still produces greenhouse gases, by incorporating processes like Bokashi fermentation, Worm Farming and Natural Fermentation, significant quantities of the gases can be reduced.

Composting of organic materials has been long implemented by farmers around the world, there are even ancient Akkadian clay tablets which refer to the use of manure in agriculture back in the Mesopotamian times (4). The system has received renewed attention from the scientific community through the 20th and 21st century resulting in numerous very precise and thorough practices for creating 'black gold' at home in almost any climate. The information is abundant and the processes are simple so there aren't many excuses left!

To learn more about Market Garden Composting and some DIY projects to get your home compost system up and running check out:

  1. Bokashi Composting in the Market Garden
  2. DIY Bokashi Bucket
  3. Building an Upcycled Compost Bay
  4. DIY Bug Hotel
  5. DIY Worm Farm Bin

How to Compost

I will be the first to admit that I am still a student in Composting College, I have been doing it for 4 years and only in the last year have I been getting a preferable soil medium. This was largely to do with a lack of attention and not following the necessary processes, my process was set and forget. I now also add Bokashi ferments and the solids from nutrient ferments which keep the compost activated with microorganisms and rapidly break down material. In the Nature Cycle Market Garden up to 90% of the organic waste is 'green, nitrogen rich' material which is not overly desirable for a compost system, but we have found our way of recycling the nutrients which I will explain here. As there are far more experienced and knowledgeable composters around I will lead you to their methods so you can find what is going to work best for you!

Materials:

  • 'Browns' (Materials which are dried and depleted in nutrients such as hay, chaff, straw, dried leaves, ash, newspaper and cardboard. They supply the Carbon Ratio required for compost)
  • 'Greens' (Materials which are fresh and full of moisture and nutrients such as cut grass, vegetable and fruit scraps, manures, coffee grounds)
  • A Compost Bay

Considerations:

  • Various materials will have differing C:N ratios and assorted nutrient profiles. By having a mix of assorted materials you are ensuring a rounded nutrient profile.
  • The recommended C:N ratios are 25-30:1 (5). So for each part of nitrogen rich material, 30 parts of carbon rich material is recommended.
  • The recommended moisture level for the compost heap is 40%-60% (6). This is to ensure a high level of microbial activity, consistent temperature and avoid anaerobic activity which produces the bad smells associated with compost.
  • The temperature range of the compost needs to remain between 32C-60C to facilitate efficient breakdown.
  • The temperature needs to be maintained at 45C-55C for a minimum of 5 days to ensure significant reduction of pathogens and weed seeds (7).
  • Sufficient temperature and moisture levels are best obtained in piles of 1m3 or larger.
  • Layering is not overly necessary, if there is enough material on hand, blending it all together and putting it premixed into the bay is easier.
  • A compost heap will decrease in size to about 1/3 of its original volume
  • A well cared for compost will not create any foul smells or attract pests

11 Steps to Compost Success:

The Nature Cycle Market Garden predominantly creates copious amounts of green material for composting. This can cause the compost to become anaerobic, rotten and sludgy. The foul smells from anaerobic composts attract pests that are drawn to the smell of decay such as flies.

However I have found a way to compost all this organic matter that works for our market garden. We have a multiple step process where quantities of organic matter are used in Nutrient Ferments and Bokashi ferments before being added to the compost. This inoculates all the organic matter with microorganisms which facilitate breakdown once added to compost while allowing the tougher cell structures like lignins and tannins to soften.

  1. Place a layer of carbon rich material over the bottom of the Compost Bay. I normally use cardboard or a thick layer of newspaper to mitigate grass and weeds proliferating through the bottom.                              
  2. Mix the organic materials together in a big pile and place into the Compost Bay.
  3. Mix 3 x 20L buckets of Bokashi/Nutrient ferments and 3 x 20L buckets of active compost from a previous batch into the Compost Bay. 
  4. Add any necessary water.
  5. Mix thoroughly.
  6. Cover the Compost with 3 x 20L buckets of active compost
  7. Keep covered with a tarp.
  8. Turn the pile every 1-3 days.
  9. Add water as is necessary.
  10. Only add fermented organic material if more needs to be added during the period of breakdown.
  11. You should have useable compost in 25-35 days.                                                  

To learn more about Bokashi Composting and some DIY projects to get your home compost system up and running check out:

  1. Bokashi Composting in the Market Garden
  2. DIY Bokashi Bucket
  3. Building an Upcycled Compost Bay
  4. DIY Bug Hotel
  5. DIY Worm Farm Bin

Recommended Reading

As I mentioned earlier I am still a student of the Composting system and am merely sharing what works for me. There are, however, some pretty unreal 'black gold' masters out there. The people and groups I have found particularly helpful are:

Geoff Lawnton and the team at Milkwood Permaculture (https://www.milkwood.net/)

The team at Gardening Australia (http://www.abc.net.au/gardening/factsheets/)

Dr Elaine Ingham (http://www.soilfoodweb.com/Thermal_Compost.html)

Eliot Coleman (http://fourseasonfarm.com/)

University of Illinois Extension (https://web.extension.illinois.edu/homecompost/intro.cfm)

Cornell Waste Management Institute (http://compost.css.cornell.edu/science.html)

References

  1. Oz Harvest(2018). Food Waste Facts - OzHarvest. [online] OzHarvest. Available at: https://www.ozharvest.org/what-we-do/environment-facts/ [Accessed 6 Jun. 2018].
  2. (2018). Food Waste Greenhouse Gas Calculator » Watch My Waste. [online] Watchmywaste.com.au. Available at: https://watchmywaste.com.au/food-waste-greenhouse-gas-calculator/ [Accessed 6 Jun. 2018].
  3. Brisbane.qld.gov.au. (2018). Food waste in Brisbane | Brisbane City Council. [online] Available at: https://www.brisbane.qld.gov.au/environment-waste/rubbish-tips-bins/recycling-reducing-waste/love-food-hate-waste/food-waste-brisbane [Accessed 7 Jun. 2018].
  4. M.extension.illinois.edu. (2018). History of Composting - Composting for the Homeowner - University of Illinois Extension. [online] Available at: http://m.extension.illinois.edu/homecompost/history.cfm [Accessed 7 Jun. 2018].
  5. Compost.css.cornell.edu. (2018). C/N Ratio - CORNELL Composting. [online] Available at: http://compost.css.cornell.edu/calc/cn_ratio.html [Accessed 7 Jun. 2018].
  6. Compost.css.cornell.edu. (2018). Monitoring Compost Moisture - Cornell Composting. [online] Available at: http://compost.css.cornell.edu/monitor/monitormoisture.html [Accessed 7 Jun. 2018].
  7. Compost.css.cornell.edu. (2018). Compost Physics - Cornell Composting. [online] Available at: http://compost.css.cornell.edu/physics.html [Accessed 7 Jun. 2018].