What is Composting?

Composting, by definition, is the oxidative decomposition of a mix of organic matter.

If there is no oxygen in your pile it is not composting. It is something else.

Composting goes back in time along way, at least to Roman times. They would pile up a year of leftover organic material and by the next planting it would be broken down enough to be used. This was a hit-and-miss system. Depending on the weather and materials they could get good compost one year or disease and pest ridden material the next.

Science has brought us a long way from there. We know now that to make good compost you need the proper proportions of 4 ingredients to make great compost.

1. Carbon: This is the ‘brown’ material. Things like dry stalks, leaves and stems fit into this group.
2. Nitrogen: This includes ‘green’ or coloured and wet material such as fruit scraps, fresh grass clippings. leaves or vegetable scraps.
These types of material are fuel for microbial oxidation. When the microbes feed they produce heat.
It is very important to know your carbon to nitrogen ratios: 25:1 and not more than 30:1.
3. Oxygen: You need oxygen for microbes to breath or oxidize the carbon.
4. Water: Water your pile to 50% – 60% moisture. Oxygen travels through air easier than through water – too much and your pile will suffocate and become anaerobic (without oxygen).
So when we design and build our compost piles we are not just mimicking the natural decomposition process. We design the piles to speed up the decomposition process and, most importantly, to increase the diversity and amount of microbial life in the compost.
There are many types of composting methods:

  • Cold Composting
  • Compost Bins
  • Sheet Composting
  • Pit Composting
  • Vermicomposting

different types of bin composting ideas – note the green to brown ratio

Vermiculture – Using worm composting systems indoors

Trench Composting


Pit Composting

Hot Composting

In this method you build your pile or row all at once. This means you need to have collected all your ingredients first instead of adding continually like you do in cold composting. The minimum size is 3′ x 3′ x 3′. It takes at least this much mass to raise the pile’s core temperature above 130 degrees F.

I have heard that composting is a lot of work. Composting is not that time consuming. You can look after your backyard compost as little as once a week (depending on how big a pile you make). You can save your kitchen scraps in a covered pail and add this to your pile once or twice a week. Just before you add a pail of kitchen scraps turn your pile. Add the new pail of scraps. Make sure you always cover each addition with a layer of brown material. Remember the ratio of green to brown is 25:1. Brown material can be material like dry leaves or stalks, wood chips or shredded cardboard (no ink please!).

In the winter, if you have a freezer you can freeze your kitchen scraps and save it for the spring. This process will help you avoid over loading your pile in the winter which could create an anaerobic condition in the spring. You should also note, you can keep adding to your compost pile through the winter as long as you turn it, add brown material with each green addition.

Decomposition will occur whether you give your pile attention or not. It is the quality of the compost that will improve with the proper balance of materials and with the proper ventilation (turning the pile). Quality compost includes a diversity of organic matter and a diversity of microbiology.

Thing You Should Never Put in Your Cold Compost Pile:

Meat Scraps
Dog and/or Cat Feces
Plant Residues that have pesticides or herbicides on them
Cardboard or paper with inks on them (unless you know it’s vegetable ink)
Things That Are Good For Your Cold Compost Pile:

Nitrogen Materials

Green leaves and/or stalks
Green grass clippings
Coloured or wet kitchen scraps (vegetable only)
Clean human urine
Carbon Materials

Dry stems and leaves
Wood chips
Clean shredded cardboard or paper
*Try and use varied types of carbon and nitrogen materials. This will help ensure you have a diverse microbiology (different microbes feed on different things).

* The more diverse your microbe biology the more nutrient uptake for your plants.

For more information on great composting, review Dr. Elaine Ingham’s work.

If you’re interested in building your own take a look at this how-to guide.

The University of Illinois has a good website on the topic to review. Note the reference to The Rodale Institute, a leader in organic agriculture.

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