Basic Gardening Techniques: Adding Humus
If you can make the effort and spare the time, you can do much to improve the fertility of yourby adding materials that are rich in humus; in the long term this will prove to be a labour-saving operation. Humus is a complex organic material in the soil produced by the decay of dead vegetable and animal matter. It has the seemingly paradoxical effect of improving the moisture-holding properties of light soils as well as improving the of heavier soils by coagulating their smaller particles.
The main sources of humus in the garden are animal manures, peat, leaf-mould, compost, bark fibre, spent hops and, for those within easy reach of the seashore, seaweed. Gardeners who live in towns or suburbs may find it difficult to obtain animal manures but, which can be made easily by any gardener, is an excellent substitute. Recipes for making it are as varied as those of Mrs. Beeton or Delia Smith, but they can be reduced to certain basic fundamentals. Almost any material of vegetable origin can be used for composting, including grass clippings, hedge trimmings, dead leaves, annual weeds etc. The house will provide kitchen wastes in the shape of vegetable peelings, tea-leaves, lettuce and cabbage leaves. Even the contents of the vacuum cleaner dust bag and old woollens, cut up into strips, can be used.
Diseased plant material, such as blighted potato leaves, and tough, woody prunings should not be included. Together with pernicious perennial weeds such as ground elder, couch grass and bindweed, they should go onto the bonfire. Bonfire ash can be added to the compost heap and is a valuable source of potash (but do not use ash from coal, coke or any other source). The potash content of the ash is quickly washed away by rain, so keep the ash under cover until you put it on the heap.
Smaller quantities of material are best composted in the special plastic or wire containers obtainable for the purpose, or in a home-made bin with slatted wooden sides and a roof to stop rain drenching the heap. Where sufficient space and vegetable waste are available, however, you can build an open heap. You will need about 1 tonne (1 ton) of material and it is best to make the heap in one go. Choose a partly shaded moist site, preferably out of sight of the house windows. If this is impossible, the heap can be camouflaged with a length or two of wattle or interlap. Heaps of this kind should be at least 1.5m (5 ft) long and of a similar width. An optimum height is 1.2-1.5m (4-5 ft). The sides of the heap should taper slightly towards the top.
Whether you use a container or not, the heap should be built directly on the soil – not on a base of stone or concrete. This will allow easy access for earthworms and the various other soil animals and bacteria, which will break down the compost materials, transforming them into sweet-smelling, dark crumbling material, rich in humus. A compost heap should be built up in layers, like a series of sandwiches. The first layer consists of 15-30 cm (6in-1 ft) of organic wastes, covered by a light layer of soil, followed by a dusting of lime (just enough to whiten the surface). These three layers are repeated until the heap reaches the required height: not more than 1.5m (5 ft). It is then capped with a 5 cm (2 in) layer of soil to keep the heat in.
The compost will take up to a year to rot down but the process can be speeded up, either by the use of one of the proprietary accelerators or by dressings of sulphate of ammonia at intervals while the heap is under construction. Such additives will also do away with the need for turning the heap and thus cut down on the labour involved.
Stable, farmyard, pigeon or poultry manure also act as accelerators and help to speed up the rotting down process if added to the heap during building. This is a good way of making the best use of organic fertilizers in short supply.
By using compost regularly as a surface dressing or ‘mulch’, the work of digging and weeding can be reduced. If compost is spread onand lightly forked in between plants, there will be no need for deeper or more thorough cultivation. Weeds are suppressed by such a mulch and any that germinate later are easy to pull out, thanks to the light friable texture created.