For a good compost heap, the layers of refuse should be 6 to 8 in. thick and should be trodden down moderately firmly. If the material is very dry, water may be added before the activator is applied. If you have to use very tough material such as cabbage stumps, it is best to break them up first on a chopping block to pulverize them. They should then be intermingled with grass mowings or similar material to help build up heat. Healthy soft growth, but not woody material, can be included. Woody material should be burnt and the ashes collected, to be stored dry for use as fertilizer. Never burn any soft material unless it harbours soil-borne diseases; to do this is a waste of potential compost.

If you use a brand-name activator, apply as recommended by the manufacturer. If you use unprocessed animal or bird manure as an activator, sprinkle a layer an inch or so thick on top of every 6 in. thickness of compacted compost material. If you use dried and pulverized sheep or poultry manure, dried blood or fish meal, add it to the heap at the rate of about 3 oz. per sq. yd. of each new 6 in. layer. If the garden soil is known to be very acid, sprinkle ground limestone, at the rate of 4 oz. per sq. yd., over every compacted foot of compost material, in addition to the activator.

mowings and cabbage leaves, provide a ventilation shaft by driving a
post of 3 or 4 in. diameter into the ground in the centre of the bin or pit, pile the vegetable waste around it layer by layer and activate in the normal way. When the heap reaches the correct height pull out the post, thus leaving an air shaft through the middle, or use a double roll of wire netting about one foot in diameter in place of the post and leave it in the heap. This is seldom necessary for small heaps but is quite a good practice for heaps that are 12 ft. by 12 ft. or larger.
Some gardeners believe that the compost heap should be turned at the end of three months, but the heap rots satisfactorily without any attention. It will probably be ready for use at the end of six months, though it need not be used for one, two or more years. If the outsides have not rotted down properly, cut them off with a spade, just as the black part of a burnt cake is cut off with a knife, and put them on the reserve compost heap to complete their decay.

When the compost is ready to use, it should look like earthy mould or moist peat. It should be dark brown or black, free from any objectionable odour and show no traces of the original materials. Eighty-five per cent of it should pass easily through a in. sifting screen.

When it is properly made, compost can be as valuable as manure, because in addition to containing plant food, it is alive with millions of microorganisms. It will also have most of the minor minerals, known as trace elements, which plants require.

What we have described embodies the general principles of compost making. Two other methods are sometimes used. The first is as follows: For the small garden make a bottomless box to contain a heap 4 ft. by 4 ft., and 3 ft. 4 in. high. Such a heap will provide 2 cubic yds. of good compost, weighing 1 ton. Bolt or screw three sides of the box together, and make up the front with loose boards slipped into position as the box is filled. Where possible. make a reserve bin.

Cut all the vegetable waste into lengths of a few inches and put it into the box with one third or one quarter of the same volume of manure. Incorporate a little soil at the same time. If  animal manure is not available, use blood and bone or dried blood at the rate of 1 to 2 per cent of the dry vegetable waste.

When the box is full, make three holes vertically through the mass with an iron bar to improve the supply of air. Cover the top with sheets of plastic or other material to keep out the rain. After six weeks dig the material out and stack it on a convenient site where it can ripen for another six weeks. Four tons of compost per year can be made in one of these 1-ton boxes.

The second method is to make the bins with old boards (old railway sleepers are excellent, because they are thick and help to retain heat), wire netting or bales of straw. The straw can later be put on the heap.

Make the bins 6 ft. by 6 ft. with open ends for ease of access, and intersperse the 6 in. layers of waste with fish meal, dried sheep or poultry manure at 3 oz. per sq. yd. When available add the urine and excreta from any animals that are kept. Once a week or so, in the summer, give the heap a good watering. When it is 4 ft. high plunge a long-tined digging fork into it in several places and move it backward and forward to provide aeration.

At the end of six months the heap will be ready. The top 9 in. and the sides may not be fully decomposed so skim them off and put in the reserve bin for further rotting.
If the garden soil is acid, use lime in addition to the fish manure meal or sheep manure as the activator, at 4 oz. for every 2 cu. ft. of waste.

Apply compost at the rate of at least a large bucketful to the sq. yd. each year. Mix it thoroughly with the topsoil to a depth of 6 to 10 in. with a digging fork or rotary hoe, or apply it as a top-dressing or mulch on the surface of the ground.The worms will pull much of it in, greatly enriching the soil as they consume and excrete it. Their tunnels aerate the ground. With the use of compost the soil will not dry out so readily, the tilth will be improved and there will be ample humus to feed seedling plants.
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