The Garden Guide

Composters and Compost Bins - review

Composters let you obey the first commandment of environmental gardening 'Thou shalt make compost unceasingly' though 'Thou shalt buy a composter' is more questionable - many people like to build their own composters. The cry to 'make compost' went up long before 'pollution' and 'conservation' became vogue words, and the humble composter, or compost bin, remains the best example of a home recycling project. The world would be a better place if cities could find ways of using composters to recycle a larger proportion of their organic wastes. Compost contains both organic matter, which provides good physical conditions for plant growth, and a better range of nutrients than any chemical fertilizer. Composters take in garden waste at the top and release compost at the bottom. Be sure to compost your organic kitchen waste as well as your garden waste (particularly banana skins) - kitchen waste has the extra plus of being devoid of weed seeds!

The merits of composting go beyond just recycling. You are what you eat is true for plants as well as for humans. Using compost will result in a healthy, nutrient rich soil that will need less additional fertilizers. Plants living in compost-rich soils require less chemical pesticides. Strong, healthy plants are less susceptible to disease, just as healthy humans are less susceptible to disease than less healthy humans. Compost helps regulate the pH of the soil and also improves the structural composition of the soil, enabling water and air to circulate better. The dark colour of compost means that compost-rich soil warms faster as dark colours absorb heat better than light colours.

Vegetable waste is converted to compost by the natural process of rotting. This requires air and moisture. Air supplies oxygen to worms and microbes that decompose organic matter. Water is always necessary for life but if the compost is saturated there will be no air and no life. The rotting of compost is faster in warm conditions and since the biological process generates heat, compost heaps can become very warm. Composters aim to keep vegetable material oxygenated and wet but not water-logged. It is important to turn your compost pile regularly to keep it well oxygenated - this will ensure that the composting process is faster and less smelly. If your compost heap is not well oxygenated the aerobic organisms responisble for decompostion will die. In the absence of these aerobic organisms, anaerobic bacteria responsible for producing fouly smelly gases will multiply.

Unless you have multiple compost bins, you would do well to choose a composter that opens at the bottom allow easy access to the fully rotted compost while continuing to add new waste matter to the top of the bin.

A composter should be at least 1 metre (1 yard) square or diameter. If the sides are sloping the compost settles more readily.

Composters and compost bins can be a bit of an eye-sore so should be kept hidden!


Composter bin

Composter input

Composter output - black humus

Rotating composter

Conical composters let the compost slip to the base, for removal