The addition of sufficient organic material in the form of animal manure or vegetable compost should cure the deficiencies of an infertile soil.
In its decayed form it is known as humus and one way in which humus aids fertility is by storing nitrogen.
The bacteria in the soil convert nitrogen into ammonia and this essential nutrient is released to the plant roots in the form of nitrates.
Humus also absorbs and holds water so that the plant roots have time to take it up.
A mixture of animal manure and straw is regarded as the best soil conditioner, as it is particularly rich in nitrogen, phosphorous, and potassium and also contains good organic material.
The nutrients are not in a form which can be immediately absorbed by plants but as the organic material begins to decay, they are converted by bacteria into chemical salts and will be taken up by plant roots.
Garden compost is formed from rotted down vegetable waste.
It is an excellent substitute as it returns to the soil all the materials taken out during plant growth and helps to improve the soil structure.
It is simple and economical to make a compost heap in the garden itself.
The place for compost pit should be out of full view, and it should not be in too damp or shady place as in shade the waste matter will not rot down correctly.
Many waste materials can go on to the compost heap, from kitchen waste.
But disease plant roots, perennial weeds or woody stems should always be burnt.
To make a compost heap, each 300 mm (1 ft) layer of waste should be trodden or pressed down firmly to get rid of air pockets, and then watered. The compacted mass can be covered with a layer of soil, about 25mm (1inches) thick, and then the farmyard manure or sulphate of ammonia. Alternate layers can be covered with hydrated lime. When the heap is at a desirable height , cover it with one more layer of soil and give it a watering. Decomposition will be speeded up if the heap is turned about every six weeks, moving waste matter from the outside into the centre and watering any dry patches. Compost can be regarded as sufficiently decayed when the individual components can no longer be distinguished.
Fertilizers are inorganic concentrated chemical salts from natural underground.
They are available in liquid or powder form and supply essential foods direct to the plants, acting quickly when applied to moist soils.
Over application of these materials can cause soil deterioration by destroying bacteria.
The fertility of a soil is an extremely complex balance between its physiology, its humus content and its mineral content.
Landscape designer should know how each factor in the balance works to have control over the soil.
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