How the natural process of composting converts your leftovers into valuable fertiliser
Leftover food, garden trimmings and other organic waste items don’t need to be discarded. Instead they can be recycled in a process called composting. Composting is the L breaking down, or decomposition, of organic material into nutrient-rich soil. After decomposition, these materials turn into organic molecules made up of carbon dioxide, water, simple sugars and salts. Compost heaps are places where this process is accelerated from years to months or even just a few weeks.
Composting mostly takes place outdoors, and there are two main types: cold, or passive, and hot, also called active compost. Cold composting is much slower but is easier to manage. All you need to do is add the right materials and allow the natural process to take place. The soil created from this process usually can’t be recycled for at least one year, as much of the decomposition takes place slowly without oxygen.
Hot composting is more efficient, but requires you to maintain consistent layers of carbon-rich and nitrogenrich materials while optimising the water and oxygen levels regularly. The ideal temperature for quick active composting is 55 to 60 degrees Celsius. This temperature is achieved when the heap is well aerated with peak composting conditions. Adding piping into the top of a compost heap is a simple way to ensure air is entering the middle of the soil.
A RECIPE FOR RICH SOIL
What ingredients work best in a compost heap?
1 ALTERNATING LAYERS A successful compost heap has alternating layers of dry, carbon-rich ‘brown’ items and wet, nitrogen-rich ‘green’ items.
2 AIR Larger items add air pockets. Air is needed for essential microbes to survive.
3 MOISTURE Compost should be between 40 and 60 per cent water.
4 FRESH GRASS Grass clippings are high in nitrogen, which increases reproduction in microorganisms.
5 BOKASHI SOIL The soil from bokashi – a process that breaks down food waste by fermentation – can be added to compost to increase friendly microbes.
6 FOOD WASTE Scraps of food can be completely broken down into compost in just a few weeks.
7 EGG TRAYS The natural materials in egg trays break down quickly to make rich fertiliser.
8 DRY FLOWERS AND LEAVES Dry plant matter is high in carbon. The best leaves to use are those from ash, maple fruit, poplar and willow trees.
9 VACUUM CONTENTS The dust from a vacuum cleaner has some fastcomposting materials such as human and pet hair and skin flakes.
10 DRY GRASS Dry grass is a useful brown layer if it hasn’t been treated for a couple of weeks.
11 WOOD CHIPS Pieces of wood are rigid and create air p
