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Waste Management at Home - How to make a compost heap
Thursday, 21 April 2011 10:33
Composing is one of the oldest ideas in recycling. Scientifically composing is defined as the biological decomposition of organic wastes under controlled conditions. Good compost is made with simple rules of assembling materials in the correct proportion, aeration, water (being careful not to over water) and heat or earthworms (vermi compost).

A variety of containers can be used from constructing a wooden box to chicken wire bins that keep the compost neater, but a heap placed directly on to the soil is just as good. A box constructed of timber should have air holes between the timber slats to ensure aeration and should not be higher than 1.5m. Two boxes are ideal – as one matures, the other is being filled. Bricks or clay pipes at the base will help the air circulation.

These must be spaced about 10cm and covered with woody plant stems or small twigs. Do not place on concrete as the soil base helps with aeration and drainage.

A good guide for assembling materials in the correct proportions is to think of them as "greens" and "browns". Greens are fresh green fresh matter such as grass clippings, vegetable waste, fresh leaves, etc which nitrogen rich is and browns are fallen leaves, straw, sawdust, shredded newspaper, etc containing high proportions of carbon. The greens would be the "wets" and the browns would be the "dries". Up to 10% of the material can be rough as if small stick and pruning, which will probably, not break down but will help with aeration and prevent material from packing down and clogging up.

Start by mixing greens together. Chop up anything that is too big to mix. To get the correct proportion of carbon and nitrogen spread out 2 buckets of browns and top with 1 bucket of greens. This is best done outside a container. Repeat the process and then add some sprinklings. These come in many forms from ground limestone or wood ash to bone meal or use organic compost activator found at garden centres and then add a few handfuls of soil. Liquid is then added, 1-2 litres with a fine mist spray or watering can being careful not to over water. Repeat this process 2-3 more times until all material is used.

The layered material then needs to be mixed before adding to the container. Use a fork and mix thoroughly until evenly distributed. Add to the container and turn every 4-6 weeks.

It is a common mistake to use too much water. Remember that "greens" may not look wet but can contain up to 95% water. The overall moisture content should be 60-65% moist as a wrung-out sponge. Not enough moisture is better than too much water. It will just take longer to moisture. Compost can be made in 6-8 weeks, or it can take a year or more. In general the more effort the quicker the compost. When the material has turned a dark brown and has an earthly smell the composting process is complete. It is then best left for a month or two to mature.

  • Ensure that your heap is covered in wet weather.
  • Dry browns (fallen leaves etc) can be kept indefinitely. Collect in autumn and store in plastic bags.
  • Evergreen trimmings and pine needles do not rot and should be avoided.
  • Flies and unpleasant smells are an indication of incorrect making, usually too much water. Try adding more "dries".
  • Shake as much soil off roots as possible before adding to the compost.
  • Newspaper in quantity should be recycled for more paper, but small amounts or paper towels can be used in compost.
  • Kitchen scraps of fruit and vegetables, tea bags coffee grounds and egg shells should be used, but avoid animal products and cooked food.
  • Do not compost coal and coke ash, cat litter, dog faeces or glossy magazines.
  • A shredded can be very useful for woody material.
  • Diseased plants should be avoided.
  • Compost heaps are made up by a host of small and microscopic creatures. These are not pests and will not overrun a garden.

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