How to Use Organic Matter
Soil fertility in gardens can not be improved overnight, but it will improve steadily by the regular addition of organic material. But getting hold of reasonable quantities is not always easy. What are some of the options? Any animal or poultry manure, always as well rotted as possible and mixed with plenty of litter and straw; treated sewage sludge and municipal waste, provided they are guaranteed free of toxic metals; seaweed, used fresh, dried or composted; spent mushroom; spent hops and slaughterhouse waste where obtainable; straw, which is best composted before use peat, which is expensive and adds humus but no nutrients; leafmould; and last, but not least, home-made compost.
Compost can be made from any vegetable wastes — household, garden, or collected from the wild. Just avoid diseased material andwhich have gone to seed, and chop up tough material such as stalks into pieces about 5cm (2in) long.
Of course, you can buy compost bins, but home-made ones are best, even for small amounts of waste. Compost is best made in bins at least 90cm (3ft) square and 90cm (3ft) deep (otherwise heat is not built up), with three walls of good insulating material such as breeze blocks, bricks, timber or straw bales. Make the heap on a base so that worms can move in during the final stages.
Start with an 8cm (3in) deep layer of brushwood, broken bricks or pipe drains, to ensure drainage and aeration, if possible covered with a strong wire screen, about 2.5cm (1in) mesh, as a base for the compost. Ideally build the compost up in layers about 15-22cm (6-9in) thick, mixing together thoroughly different types of waste, which must be slightly moist. Never put in a mass of one substance, such as lawn mowings, which will simply form a nasty sludge. It is much better to accumulate a lot of waste in, say, a separate garden rubbish bin, to add to the heap in one go, than to add a little daily.
In winter, a source of nitrogen should be mixed into each layer to stimulate bacterial activity. This can be poultry or animal manure, a proprietary compost activator or concentrated seaweed extract, ammonium sulphate or other nitrogenous fertilizer. In summer there is so much nitrogen-rich fresh green material in the heap that this is unnecessary.
The complete heap can be held in place with a sheet of plastic, perforated with aeration holes about 2.5cm (1in) diameter, about 25cm (10in) apart. Cover this with an insulating layer of hessian sacks, matting, old carpets, old hay or straw, and the heap should be ready in about three to four months — rich-looking material with a soil-like texture.
Where this procedure is too much trouble, make a rough and ready pile of vegetable waste and cover it with plastic on completion. But it will need to be left for at least a year before it is sufficiently decomposed to use. If you are short of space, leave it uncovered and grow gourds andon it while it rots.
How to Use Organic Matter
Apply the material at 4.5kg (10lb), ie. about 2-3 buckets per square metre. This should be done annually wherever possible, as soil reserves of organic matter are continually being depleted and much, of course, is removed from the soil when the vegetables are harvested. The most efficient way to use organic matter is to work it thoroughly and evenly into the soil when digging, not, as was traditionally advocated, putting it in a layer at the bottom of a trench. It can be spread on the surface in a layer several inches thick, allowing the worms to work it in. This method, which protects the surface, is especially useful on light soil where the soil structure is damaged by rain, although organic matter is not so evenly distributed through the soil.
In fertile garden soils very satisfactory crops can be grown without the use of artificial fertilizers. But many gardens lack essential nutrients : nitrogen in particular is washed out of soils during the winter and is often in short supply. In such cases yields can be boosted with artificial fertilizers.
There are so many variables — soils, crops, for example — that it is impossible to make specific recommendations on how much of which fertilizer to apply. But provided most of the plant waste in the garden is returned to the soil as compost, an annual dressing in spring, about a month before sowing, of a compound fertilizer containing equal quantities of nitrogen, phosphorus and potash (eg. 10 : 10 : 10 as marked on the bag), applied at the rate of 60-90g (2-3oz) per square metre, would cater for most crops under average conditions.