Compost is an earthy mass of decomposed plant material that can be added to gardens and planters to improve soil structure and provide a small amount of nitrogen essential for plant growth.
Layering organic matter such as leaves, vegetable peelings, grass cuttings and even eggshells into the heap results in the gradual breakdown of matter over a few weeks.
Micro-organisms within the bin set about decomposing the organic materials and, in doing so, release nutrients back into the soil. Conditions inside the heap need to be just right in order to aid the efficient breakdown of materials and release of nutrients.
Compost bin structure
Newspaper – Micro-organisms can only use organic molecules that have dissolved in water. Therefore the heap must stay moist – 40-60 per cent moisture is optimum. Carbon-rich paper holds water and helps keep the soil damp but not wet.
Soil – Micro-organisms will continue to use any spare nitrogen for their own development until all the material has been broken down. Therefore compost should not be used to aid plant growth until it’s fully rotted.
Straw – The straw layer helps aerate the pile. Oxygen is essential for helping micro-organisms to break down materials.
Stones – Maintaining the optimum moisture is key so putting a layer of stones at the bottom drains excess water (aided by a tap) and allows air to circulate.