Food Scraps - Which Bin

What happens to garden waste after it has been collected?

Garden waste collected at the kerbside is taken to a composting site where it is turned into a nutritious soil conditioner.

When the garden waste arrives at the composting site any material that is not compostable is removed, the remaining waste is then shredded and then laid out in a long pile to decompose, usually in the open air.

Open air windrow composting is generally used for garden waste materials only and cannot accept catering or animal wastes (such as food from household kitchens). Garden wastes containing these other types of material have to be processed using methods such as in-vessel composting (IVC) or anaerobic digestion (AD).

The process at a composting site is similar to that that takes place in home compost bin but is actively managed to speed up the process. However, due to the amount of material the temperature reached is a lot higher than in a normal household compost bin. Temperature can reach up to 60°C. This higher temperature means that the enzymes and bacteria are quickly put to work resulting in finished compost in just a few weeks.

The material is turned frequently to provide much needed oxygen to micro-organisms that help decompose the material. High temperatures kill off any harmful microbes, weeds and plant diseases.

The final part of the process involves screening the compost to remove any remaining contaminants and to grade the material for various end uses. Any compost that is still oversized or hasn't decomposed enough, can then be put back through the process until it has composted down sufficiently.

The whole process takes between 8 and 16 weeks, depending on the final use for the compost.

Although composting sites have measures to remove contamination, it is important that garden waste collected for composting is as clean as possible and that plastics and large stones are kept to a minimum, in order to ensure that a quality product can be made. It is also important that grass cuttings where herbicides have been used aren't put in the green bin.

There are also some great websites to assist with ways to use food scraps including recipes, worm farms, composting and the like.

When food scraps are sent to landfill, they decompose to produce methane, a greenhouse gas with more than 20 times the global warming capacity of carbon dioxide. Decomposing food scraps in landfill are also a potential source of organic leachates that can contaminate surface and ground water.

The amount of greenhouse gases produced by food waste in Australian landfill each year is equivalent to the emissions of Australia’s steel and iron ore industries combined, according to RMIT University in Melbourne.

A recent audit undertaken found that more than 27% of the contents of a general waste bin for landfill is food waste. Fruit and vegetables constitute about half of all food waste thrown out, 75% of which is edible.

It makes sense to divert organic food waste from landfill by converting it into compost to be returned to the earth.

While the average consumer is not a large environmental polluter, finding ways to reduce food waste throughout the day can help a person avoid contributing to the problem.

Below we will learn about how to reduce food waste in the home, at school, and on the go.

  • Avoid buying too much

While mould is a definite sign that something belongs in the garbage, it is not necessary to throw out foods that are slightly past their prime.

For instance, many greens and vegetables may slightly soften, they are just past ripe and make excellent additions to soups, smoothies or baked dishes. Left over scraps are great for making soup stock.

  • Make a weekly menu

Making a meal menu for the week can help people to organise their food usage and cut back on waste.

  • Always Make a Shopping list

Buying foods that are already in the home can ultimately become another source of waste. Taking inventory of the food in the house and making a grocery list before going to the shops, may help people avoid purchasing unnecessary foods and save money.

  • Organising the kitchen with "FIFO"

Organising the fridge or pantry can help keep track of what you have in the home and identify foods that are already to eat.

FIFO stands for "first in, first out" place newly purchased foods at the back will encourage people to use the food at the front first.

  • Store Food Correctly

Perishable items, such as fruit and vegetables have a best way to be stored to avoid spoilage. Some tips:

  • Keep fridge below 5 degrees
  • Store cooked foods on shelves above raw foods
  • Storing food in sealed containers.

Note: some foods give off natural gases and make nearby foods spoil faster. Storing apples, bananas and tomatoes apart from other perishables may help keep them all fresh.

  • Freeze leftovers

Freezing foods can help preserve them for later use and prevent them from spoiling. Many fresh fruit and vegetables keep well when frozen, extending their shelf life and reducing waste.

Other foods preserve well in the freezer as well – ie breads, meats and even some prepared dishes.

Freezing foods that people use less often, such as herbs, is also helpful. Freezing fruit and vegetables when they are in season can also reduce the need for buying them when they are out of season and more expensive.

  • Eat Leftovers

As part of a meal plan, you can choose to make more food and use these for lunches or to store quick meals in the fridge and/or freezer.

Investing in quality food containers that do not leak and are light and convenient to carry can help. Making extra portions of evening meals to keep in the fridge as ready to go packed lunches can eliminate the needs to spend extra time making lunch and save money.

  • Make Broth or Stock

Excess food, scraps and even some bones are great ingredients for various stocks or broths.

Boiling excess vegetables, peelings and other scraps can make a hearty vegetable broth. It is best to store homemade broth in the fridge and use it within a few days.

  • Compost scraps

Most meal preparation leaves scraps from the stems, peels and unusable bits of food. Even coffee grounds and tea leaves make great additions to a compost heap.

Creating a compost heap is one way to help reduce waste by turning these scraps into nutrient rich fertiliser.

With composting, you are creating rich humus for your lawn and garden. This adds nutrients to your plants and helps return soil moisture.

Composting can divert as much as 30% of household waste away from the garbage can. That is important because when organic matter hits landfill, it lacks the air it needs to decompose quickly. Instead, it creates harmful methane gas as it breaks down.

The microscopic organisms in compost help aerate the soil, break down organic materials for plant use, and ward off plant disease.

Composting offers a natural alternative to chemical fertilisers when applied to lawn and garden beds.

What to Compost?

What you put in your compost will depend somewhat on what kind of composter you have, but some general rules do apply.

All compostable materials are either carbon or nitrogen based, to varying degrees. The secret to a healthy compost pile is to maintain a working balance between these two elements.

Carbon rich matter includes – branches, stems, dried leaves, peels, bits of wood, shredded brown paper bags, coffee filters, coffee grounds, egg shells, straw, wood ash.

Nitrogen or protein rich matter includes – manures, food scraps, green lawn clippings, kitchen waste and green leaves.

A healthy compost pile should have more carbon than nitrogen. A simple rule of thumb is to use one third green and two thirds brown materials. The business of the brown materials allows oxygen to penetrate and nourish the organisms that reside there. Too much nitrogen makes for a dense, smelly, slow composing anerobic mass. Good composting hygiene means covering fresh nitrogen rich material, which can release odours if exposed to open air, with carbon rich material, which often exudes a fresh, wonderful smell. If in doubt, add more carbon.

Items not to compost

Do not compost meat, bones, fish scraps (they will attract pests) unless you are using a composter designed specifically for this purpose.

Avoid composting diseased plants, since you might spread weed seeds or diseases when spreading your compost.

Don’t include pet manures in composts that will be used on food crops.

Banana peels, peach peels and orange rinds may contain pesticide residue and should be kept out of the compost.

How to Start a Compost

Start your compost pile on bare earth. This allows worms and other beneficial organisms to aerate the compost and be transported to your garden beds.

Lay twigs or straw first, a few inches deep. This aids drainage and helps aerate the pile.

Add compost materials in layers, alternating moist and dry. Moist ingredients are food scraps, tea bags, seaweed etc. Dry materials are straw, leaves, sawdust and wood ashes. If you have wood ashes, sprinkle in thin layers or they will clump together and be slow to break down.

Add manure, green manure (clover, buckwheat, wheatgrass, grass clippings) or any nitrogen source. This activates the compost pile and speeds the process along.

Keep compost moist. Water occasionally, or let rain do the job.

Cover with anything you have – wood, plastic sheeting, carpet scraps. Covering helps retain moisture and heat, two essentials for compost. Covering also prevents the compost from being over watered by rain. The compost should be moist, but not soaked and sodden.

Turn – every few weeks give the pile a quick turn, this aerates the pile. Oxygen is required for the process to work, and turning adds oxygen. Once you have established your compost pile, add new materials by mixing them in, rather than by adding them in layers. Mixing or turning the compost pile is key to aerating the composting materials and speeding the process to completion.

How long does compost take to mature?

The speed at which organic matter breaks down depends on a number of things:

  • The size and type or organic material added to your pile. Chopped and shredded material breaks down more quickly than whole material. A correct ratio of brown, carbon rich ingredients to green, nitrogen rich ingredients will also speed decomposition.
  • How often you turn your pile while its composting. Turning a pile improves aeration and helps move larger bits to the centre where they will decompose more quickly. A compost tumbler makes this process quick and easy.
  • Whether you’re using a hot or cold composting method. Hot composting, while more work to monitor and set up, will break down food waste more quickly than cold. In hot composting, its easy to tell when the compost is finished. The temperature of the pile drops and doesn’t heat up again when turned. Hot composts work best with shredded materials and a carbon to nitrogen ratio of 30 to 1. Compost tumblers can work as hot composters, because their sealed design helps conserve heat and mix the hot composting matter with new material.

Depending on the factors above your compost could take anywhere from 4 to 12 months to fully decompose. If you’re using a tumbler, you’ll have ready-to-use compost in 3 weeks to 3 months.

How to finish compost

There is no shortage of options for using the precious results. A more common problem, is that there is rarely enough compost to go around.

Before your raid your compost bin, remember that using compost before it is ready can attract pests and damage garden plants. It can also use up nutrients in your soil, making these same nutrients unavailable to your garden plants.

To make sure your compost is ready, grab a handful and have a look.

  • Is the texture crumbly and smooth? Depending on what you add to your pile, there may also be wood or fibrous pieces, but nothing should be recognisable.
  • The smell should be sweetly fragrant and loamy, like being in a forest on a wet day. Traces of ammonia or sour odours indicate your compost needs more time to mature.
  • A dark rich colour.

Mature compost will be reduced by about one third of its original amount.

Benefits of using compost in the yard and garden

Once your compost is ready to use, add it to the soil at any time of year to get the following benefits:

  • Improved moisture retention – soil fortified with compost holds more water for longer periods. You’ll water your garden less often, saving time and money.
  • Better soil structure – more organic matter in your soil means more air pockets for water and nutrients to travel unimpeded.
  • Improved nutrient levels – compost is high in the big three nutrients needed by garden vegetables – nitrogen, phosphorous and potassium. It also contains trace elements such as calcium, magnesium, iron and zinc.
  • Balanced soil pH – adding compost prevents your soil from becoming too acidic or alkaline.
  • Healthy natural soil organism – critters like worms and flies feed on compost ingredients. They also help out your garden.

There are also some great websites to assist with ways to use food scraps including recipes, worm farms, composting and the like.