written by Heather Menzies

There’s something magical and almost mystical about turning dead and decomposing matter into soil that will sustain new life. There’s also a lot of practical knowledge involved. Here’s a distillation of what Simon Nattrass shared with Commons gardeners at a composting workshop on Earth Day eve.

The carbon/nitrogen ratio should be 30 to 1.

Good carbon sources are straw, deciduous wood shavings and leaves, shredded newspaper and cardboard, dry old flower stalks and other woody stems (just not wood itself).

Good nitrogen sources are grass clippings (preferably left to dry a bit first), weeds (but not the roots),) and animal manure (chicken manure very high in nitrogen; horse manure much lower) and raw fruit/vegie scraps (Cut up any lemons first, and don’t use onion; check online for other things to avoid.)

Aerating the compost is essential to support the aerobic microbes at work, and deter the anaerobic. This best achieved by layering, and occasional turning. Perforated pipes can also be inserted.

Wood ash is good, if sprinkled in as a layer; not too much though.

The temperature inside the compost heap/bin should be bathwater warm, not hot. Excessive heat means too much nitrogen.

Keeping the moisture level right is also essential. The compost should be moist like a chocolate cake, not wet; when grabbing some into your hand and forming a fist, it should stick together at least a bit.

The least-labour method involves adding new materials (beyond kitchen scraps) three or four times a year, and turning the heap only once. If you have a 3-bay compost setup, this turning could be into the second bin where the compost will continue composting for the first of 2 years before use.

You can get useable compost faster if you turn and add material more often, and if you add red wriggly worms. They produce half their weight in castings (poop) every day.

Centipedes, millipedes and spiders in your compost is good; it suggests there’s good activity going on. Sowbugs tend to signal too much carbon.