Garden cuttings can be converted into compost and other soil improvers, instead of being sent to landfill where they will breakdown to produce potent greenhouse gases.
In the anaerobic (zero oxygen) conditions of landfills, organic waste (including garden cuttings) decomposes to produces methane, a greenhouse gas with about 21 times the global warming capacity of carbon dioxide. It also uses up the very limited space available for landfill.
By composting organic waste, valuable nutrients and energy can be recovered for re-use in the form of compost, mulch, fertilisers and other soil conditioners. These are used to improve the structure, fertility and health of soils in agricultural, horticultural, landscaping and gardening. Organic waste can be composed aerobically to avoid or vastly reduce the amount of methane generated and reduces the amount of water required for gardening and agriculture. Alternatively, anaerobic composting of organic waste produces methane for biogas capture and use in electricity generation.
Many commercial recycling operators and local councils accept garden cuttings for recycling, including branches, stumps, plant cuttings and grass clippings.
Garden cuttings are shredded and mixed with other types of organic material for composting.
The most commonly-used method of composting food waste in Australia is aerobic windrow composting (also called hot composting). In this process, different types of organic waste are thoroughly mixed, before the material is formed into ‘windrows’ or mounded rows. The windrows are regularly turned and managed to optimise aspects such as aerobic (with oxygen) decomposition and pathogen destruction. Another popular process that uses aerobic decomposition is in-vessel composting, using variations of large enclosed composting containers.
Biogas, including methane, is produced in anaerobic conditions. As of 2007, there were 58 biogas generation facilities in Australia, producing biogas for electricity generation.
Compost Australia - a national program designed to build and spread knowledge about the production, benefits and use of recycled organics (compost). Created by Compost Australia.
Recycled Organics Unit (The University of NSW)