Making a compost heap
Throwing away garden and domestic refuse which could make compost is wasteful and uneccessary. Grassmowings, weeds, vegetable peelings and dead leaves can all be used to make a rich, healthy fertiliser, and soil conditioner for the garden, all for free. Compost making is not difficult, and can be successful in any size garden.
What is Compost?
All materials of animal and vegetable waste eventually rot down and return to the soil with the dead of many tiny micro-organisms. A compost heap is simply an environment where this natural process can be speeded up. The resulting material is rich in nutrients and 'humus' (decayed organic matter, important in soil to help it maintain a free-draining structure).
To encourage a strong population of micro-organisms they must have favourable conditions - i.e. food, warmth, moisture and air. Your compost heap must therefore be constructed in a way which allows these requirements.
Virtually anything which once lived can be put on a compost heap. Woody things like shrubs prunings and brussel sprout stalks should be finely chopped first. Evergreen trimings and pine needles do not rot well and should perhaps be avoided.
Mix Materials Well
Large amounts of one substance tend to give an 'unbalanced' diet for micro-organisms and therefore putrefaction may occur offending you and your neighbours! Mix large amounts of lawn mowings, etc., with other garden residues.
Compost heaps should be moist but not wet. Wet any dry material which you add to the heap and water the heap in dry periods of summer - but protect heaps from excessive rain. Rain will 'leach' the nutrients which you are trying to save, e.g. nitrogen and phosphates.
The compost heap must have air. Clay pipes or bricks at the base of the heap help air circulation - also a slatted side to a container allows air to filter in higher up. A compost heap should never be higher than 5 feet (1.5m) or 6-7 feet (2.1m) square, so that air can always get to the centre. Airless conditions encourage anaerobic bacteria which putrefy material.
A healthy compost heap should reach temperatures of 140 degrees Fahrenheit (60 degrees Celsius) at centre, and this heat will kill weed seeds and steilise your compost. However to maintain a good temperature in periods of cold and therefore sustain the process at work you should insulate your heap. Old carpet on the top and bales of straw or corrugated iron around the sides work well - but don't completely block the airflow.
The correct balance between carbon and nitrogen (the CN ratio) must be maintained in the heap. Many plants (particularly older ones) have a lot of carbon in them and micro-organisms need nitrogen to break it down. This can be added in many forms as an 'activator' layer when you build your compost heap. Animal manure (horse, pig, poultry), bone and fish meal and manufactured products (e.g. from seaweed) make excellent activators. If you live in a town or you have acid material in the heap a layer of lime can help neutralise this. Some gardeners recommend layers of garden soil to 'innoculate' the heap with the right micro-organisms - but don't overdo this. Other high 'N' additives include a layer of nettles or comfrey.
If you can spare enough room for two compost boxes 'turn' your compost about every 4 to 6 weeks, so that all material spends time at the centre and rots properly.
If you cannot do this, only use the best composted material when you need it, and use other stuff as the basis of your new heap.
Using your Compost
In the summer compost should take as little as 12 weeks to make, but in winter it takes longer. A mature compost should be dark brown, friable and should smell like good soil. You can use your compost in a number of ways. If you want to use it to feed your plants put it around them in spring when plants are beginning to grow. This way nutrients will not have a chance to be leached by winter rain, and whilst the plant is dormant.
However, if you want the compost as a soil conditioner put it on in the autumn so that the soil is protected through the winter.
Constructing a Compost Box
- Fork over the ground where you plan to place the box.
- Bricks or clay pipes. Cover with brushwood.
Lay these at the base to ensure good aeration.
- Use timber treated with preservative to assemble your box.
- With 2 x 2 inch uprights and half inch thick planks, make a three sided box as shown below.
- Nail planks to the uprights with a half inch gap between them.
A "New Zealand" type compost box
- At the front of your 'E'-shaped box have two uprights half an inch apart so that boards can be dropped between them to make a removeable front.
- Remember to cover your compost heap in wet weather.
For further information
Ask for details of compost making and recycling material from the following addresses:
The Soil Association
The Soil Association, Bristol House, 40-56 Victoria Street, Bristol, BS1 6BY
The national charity for organic growing have information on composting on their website:
Reproduced with the kind permission of Bay Tree Nurseries, Spalding