Composting involves turning unwanted waste such as food scraps, lawn clippings, hedge trimming etc into valuable plant food.
There are three main types of composting systems:
* traditional composting piles or heaps that rely on heat to break down plant matter;
* vermiculture systems such as domestic or commercial worm farms where worms do all the work and produce a valuable liquid fertiliser;
* and the bokashi system which involves composting food scraps in a bucket with the help of special microorganisms.
A good guide to all these systems may be read at the following website:
Create Your Own Eden also runs regular FREE composting workshops in Auckland:
The schedule for 2012 classes that are held in Auckland (and booking info) is at this link:
This link at the site of The Soil and Health Association has useful information about composting, including what sort of plant nutrients are supplied by different materials. http://www.organicnz.org/organic-gardening-soil/
NB: Please note that grass clippings, hay and manure added to compost heaps should come from spray free lawns/fields. The herbicide aminopyralid can contaminate grass and hay and manure from animals that have eaten contaminated grass and hay. Using aminopyralid contaminated ingredients can result in a compost that kills many types of vegetable plants including lettuce, beans and tomatoes. (See http://www.compostgardening.com/ and http://www.guardian.co.uk/environment/georgemonbiot/2011/jul/15/vegetables-disease-aminopyralid-pesticide?INTCMP=ILCNETTXT3487 ) In NZ aminopyralid is sold by Dow under the brand names “T-Max” and “Tordon Brush Killer XT”.
It is also a good idea not to compost imported bananas as some very toxic pesticides are used in banana plantations.
The site below is totally dedicated to compost, and though it is an American, has a lot of information that is relevant to NZ, including how to build different styles of compost heaps.
This link shows how to make a worm farm out of recycled materials.
There are some potential health risks from handling compost; please read the Health and Safety page of this site for details.
NZ Made Composting Systems
1) General compost makers
Horto Compost Bins
Vitality for Life
2) Worm farms
Worms Are Us
3) Bokashi Bucket Composting Systems
Businesses Supplying Bulk Compost
Lower North Island
0800 888 200 (producing a BioGro certified product)
A note about commercially prepared compost: Some brands of compost incorporate sewage sludge (often called “biosolids” into their compost. This is best avoided as sewerage sludge can be contaminated with heavy metals. Sewerage sludge is not permitted under organic certification schemes.
Some commercially prepared (and home made compost) is too “green” – meaning that it contains too high a proportion of bits of stick, bark etc that has not yet rotted down. As the “green” compost begins to break down in your garden, it can deplete nitrogen levels in the the soil, causing plants’ leaves to yellow. Applying a nitrogen rich fertiliser will help if this is the problem
NB: If you can help improve this page by suggesting other composting making products and/or suppliers or good quality compost, please do so.