Sort your wastes to compost well

Raw and cooked kitchen scraps are generated routinely in our homes. They are generally compostable but won't compost well on their own.

The secret to perfect composting is gather the right types of wastes to compost together.

Compost with balanced nutrition

Composting is governed strongly by the relative amounts of carbon and nitrogen in a composite, that is, by its C/N (carbon/nitrogen) ratio. It is slow with a high C/N ratio due to an excess in carbon. It is quick with a low C/N ratio but with a loss of precious nitrogen and problems like bad smell or compost flies.

A waste composite composts best when its C/N ratio is the 25-30 range, where the carbon and nitrogen present in your wastes are used up at a similar rate. There is balance between C and N.

By convention, compostable wastes are considered either carbon-rich or nitrogen-rich, which corresponds to high C/N and low C/N ratios respectively.

We can achieve the best ratio by identifying our C-rich and N-rich wastes, and adjusting how much of each type goes in.

Sort by compost nutrition

Getting compost nutrition balanced is reasonably simple using common household wastes. As you might guess, we want to sort our wastes into N-rich and C-rich first.

In short, kitchen wastes are usually N-rich, while non-food wastes like paper products and leafy plant matter are C-rich. See below for a list of familiar C-rich wastes ^[1] .

After sorting your wastes, layer C-rich wastes on top of N-rich wastes to create a composite. This helps you to estimate visually what your current ratio looks like, and to make it easier to adjust their relative amounts.

Composting with Bioverter

Bioverter is well suited to compost this 2-layer combination, with vegetarian (vegetable and fruit) scraps making up up two-thirds of the total wastes. In other words, you use twice as many kitchen scraps than non-food wastes to get the right compost nutrition for our self-aerating composting system.

In contrast, tumblers and open-ended compost bins are suitable for composting garden wastes with some plant-based kitchen wastes if you are willing to aerate the wastes often by hand.

Quick tips

Finally, extra hints for optimal composting:

• You compost vegetable and fruit wastes better by breaking or cutting the wastes into pieces smaller than 25 mm in size.

• Protein food wastes (e.g. meat, poultry, fish and cheese) can be included in your kitchen composite if you take care. Cut them into tiny bits and disperse thinly among your plant-based wastes. Use a thicker covering layer to provide more carbon to match the extra nitrogen in scraps with more protein.

• Be careful to exclude wastes which hinder composting. Examples include oil, fat, bones, large fruit seeds (avocado, mango, peach, nectarine), walnut shells, woody plant parts, dry leaves, seeded weeds, diseased plants, and dog/cat faeces.

To get the most out of Bioverter, refer to composting tips.

Happy composting with your sorted and nutritionally balanced wastes!