Composting

Composting is the process whereby micro-organisms and fungi break down organic matter and turn it into compost, a stable humus-like material. It’s occurring naturally all around us: think of the forest floor where leaves decompose to the dark humus found below. Compost is an essential element of healthy soils supplying nutrients to plants, enhancing soil structure, increasing the capacity of soils to retain water, binding and retaining nutrients, and reducing soil erosion. Plants grown on soils with compost are healthier and more resistant to diseases. Composting is a way of turning problematic organic wastes into a valuable resource for agriculture.

Composting at CAT

There are two broad approaches to composting; hot and cool. At CAT we compost in both ways. Hot composting is quicker but takes more careful control over the process conditions, and sometimes the input of energy. The decomposers are microscopic with bacteria and fungi doing the work. Cool composting is slower, takes up more space, but is simpler to manage. The decomposers occur at all sizes from bacteria up to visible creatures like mites and worms.

Food waste

This is composted hot in a machine that turns and aerates the food waste. Electricity is used to power the motor and provide additional heating when required. Material passes through the machine in a couple of weeks and then is put in bays to mature for a further three months.

Toilet Waste

This is composted cool. We have several composting toilets on site that compost excreta in a chamber below the toilet pedestal. We also have a reedbed sewage treatment system that separates the solids from the sewage of the entire site, and these too are composted. To get the right balance of ingredients for effective composting we add extra carbon to the excreta, usually in the form of straw, sawdust and paper towels. We leave the compost for a year to ensure all pathogens are dead. In order to remain a Soil Association certified site we have to leave the compost for a further year (so two in total) before applying it to land. Compost is then used on our ornamental gardens.

For more information about compost toilets see our fact sheet.

Household composting

For information about composting at home look at our fact sheet.

Also see CAT research papers into home composting