After attending Drews compost making workshop in Adelaide last night, there were a couple of interesting points which came up that I thought might be useful to share with others.

We were focusing on building a pile in a gedeye bin, I guess your typical urban compost situation. For a quick revision of the basics, we talked about the ADAM and EVE principles, namely if you have the following in your compost heap:

-Aliveness (treat the heap as a living organism- no chemicals or other nasties to go in there)

-Diversity (variety of organic materials- kitchen scraps, lawn clippings, brown leaves, garden soil, mature compost as innoculant, lime, rock dust)

-Aeration (closely related to structure -one useful tip was to place sticks as the bottom layer of the pile for improved aeration- also crucial to turn the pile every couple of weeks)

-Moisture (watering between layers- more towards the top than the bottom to allow for percolation)

then the following benefits will result:

Energy, Vitaility, Environmental (EVE)

With regards to suitable materials, there was some discussion around possibly suspect materials such as dog and cat poo. Drews experience in terms of producing good compost was that dog poo is OK, cat poo is not so good. However, probably good to be aware that dog feces can have high levels of pathogens and may also contain anti-worming chemicals (not good for our friends in the soil!). The same basically goes with humanure - use at your own risk. It should be said that if a pile goes properly thermophilic, then most pathogens will be killed off anyway (USEPA recommend 3 days above 55 C to kill most pathogens)- the main concern I think is the possible presence of chemicals and/or antibiotics.

An interesting aspect of urban compost making is obtaining sufficient amounts of high Carbon materials to achieve the correct carbon-nitrogen ratio of 25:1. People who live in units without much of a garden may struggle to find sufficient brown organic materials about the yard to make a decent pile and balance out the high N content of fresh food scraps. One strategy in Australian urban areas is to harvest leaves fallen from deciduous street trees in autumn and winter, thereby reducing the nutrient load on the stormwater system. During times when these leaves aren't available, food scraps could be composted in either a worm farm or bokashi bin, neither of which require big volumes of carbon rich material.

I set up a bokashi composting system in my old office building of 70 people. This system works by activating a process of anaerobic fermentation inside a sealed bucket. A small amount of 'bokashi mixture (bran, mollases and beneficial microorganisms) is added between each layer of food scraps and the system must be kept airtight between openings. A liquid fertiliser is yielded by the solid material, drained off with a tap, and used as a a highly diluted feed for the garden. When the solids have fermented in the bucket (one week after filling), these are buried in the soil and turn to a nice composted soil conditioner very quickly (6-8 weeks). Bokashi systems are perfect for office environments or anywhere where space, odours, vermin or lack of organic materials for composting might be an issue. For more info or to learn how to get a system happening just google 'Bokashi composting'.

Drew also introduced us to a fantastic, low tech tool- the compost screw. This was a home made oversized corkscrew which you screw down into the pile enabling you to pull up a 'column' of compost in a gedeye bin, making for quick and easy turning and aeration.

Just a few tips to help close the nutrient cycle. I think backyard composting is a really effective, low tech solution to reduce the amount of household waste transported to landfill - it also provides us with a cheap organic soil conditioner and is very satisfying when done right. Happy composting!