Where there is any choice, it may be noted that strawy horse manure and sheep manure are best on heavy land, while cow and pig manure are better on light sandy land. Chicken manure is best stored dry for a time before use. It is then used in place of stable manure, but less freely, being much richer in plant food. From one to two pounds to a square yard is a good dressing of poultry droppings. Of ordinary stable manure no exact quantities are reliable, since the quality is so variable; its chief value lies in its bulk of humus. Generally a rough layer of, say, 3 in. all along an open trench when digging, is sufficient for the annual dressing.
Pigeon manure is similar to poultry manure, but even more valuable, and one half the quantity, i.e., from half a pound to a pound to the square yard, is enough.
Any of these animal and bird droppings can be made into liquid manure by suspending a quantity in water. The usual way is to put the manure into a sack, together with soot, if this is available, and after tying the neck, to drop the sack into a rain tub. When required for use, the liquid manure is diluted to the colour of straw. Liquid manure used too strong is liable to injure plant roots, but this can be avoided by adding to the rain tub four ounces of gypsum to every gallon of liquid.
Artificial fertilizers are generally not much needed in the new garden, but after a season of cropping some additional feeding may be wanted for the second year. The chief artificial fertilizers in general use can be grouped under three heads, corresponding to the golden tripod, according to their purpose.
1. Leaf-forming or nitrogenous fertilizers. Nitrate of soda is one of the quickest in action, so quick, in fact, that it can be used while the plants are actively growing. It is so soluble that it should never be used at any other time, or it merely seeps through the soil and is wasted. An ounce of nitrate is sufficient for two or three square yards of soil at one dressing, but this is best applied in liquid form, or dusted on the soil during showery weather. It is used on light soils, and is usually applied in the spring.
Sulphate of ammonia, a spring and summer fertilizer, is similar in action to nitrate, but as it can be mixed with other artificial fertilizers to make a complete all-round manure, it is perhaps more widely used. (It can be mixed with superphosphate and with sulphate of potash, but not with basic slag or lime.) It does not wash through the soil quite so rapidly as nitrate of soda, and is therefore better in wet seasons. Some lime must be present in the soil for sulphate of ammonia to be fully effective as a fertilizer.
Nitrate of potash (saltpetre) is somewhat similar in action to nitrate of soda, but includes the tonic potash, and so can also be classed under the third head. It is rather more costly than the sodium nitrate, and is generally used in greenhouses and on exhibition plants, such as roses and chrysanthemums. It suits all soils, and should be used at the rate of one ounce to one or two square yards.
Other nitrogenous fertilizers are nitro chalk, for heavy and acid soils, applied in the spring and summer, about two ounces to the square yard; soot, for all soils, which deters slugs, and celery, carrot, and onion fly; and calcium cyanamide, used on vacant lots of lime-free soil, seven days before cropping. Calcium cyanamide is toxic to plants.
2. Flower and fruit-forming or phosphatic fertilizers. Superphosphate of lime is one of the most widely used of this group. This is quick acting, and is generally used in the spring, and chiefly on light soils. Two ounces to a square yard is an average dressing.
Pros and Cons of Different Fertilizers
The Use Of Basic Slag
Basic slag, an insoluble fertilizer, is applied in autumn or winter, and is phosphatic. It can only become active in soils where there is plenty of humus, not in poor light soils, or chalky soils that have no humus. In a chalky soil, however, where plenty of decaying vegetation is dug into the ground during digging, basic slag would be good. It can be used at the rate of six or eight ounces to the square yard, and as it contains some lime, the proportion of lime used on the same plot can be decreased.
Phosphate of potash is quicker in action than basic slag, soluble in water, and therefore very suitable as a quick stimulant on pot plants. Its price prohibits its general use in the garden. When used under glass, about half an ounce of phosphate of potash and half an ounce of nitrate of potash can be dissolved together in a gallon of water. (Warm water will dissolve them more readily.)
Bones are also phosphatic in various forms, as coarse bonemeal or boneflour. They are useful for light soils too dry for basic slag and too poor in lime for superphosphate. Bonemeal is generally used in all parts of the flower garden. It is slow acting, and a heavy dressing can be given whenever borders are being renovated—up to .1 pound per square yard without harm.
3. Tonic, i.e., disease resisting or potash fertilizers. These are often omitted by the amateur gardener because he does not realize their importance. Lack of potash is the cause of frequent failure with apples, with potatoes, and in fact with many flowering and Fruiting plants in the garden. Potash can be applied to growing crops, but the pure form of sulphate of potash should be used for this purpose. Not more than an ounce to the square yard should be needed at one dressing. Sulphate of potash is best applied in spring and autumn, and is suitable for heavy soils, and also for indoor use.
Kainit is sulphate of potash with many impurities present. It can be used in autumn and winter, but not on actively growing crops. By the spring, when the plant roots become active, the Impurities will have been washed away. Kainit checks pests and fungoid diseases, and is useful for asparagus and potatoes. Two ounces to the square yard is a normal dressing.
Muriate or chloride of potash is also unsafe to use in the active growing season, but in some districts this form of potash is preferred to kainit.
Phosphate of potash has only one fault, its comparative costliness.
Other sources of potash salts are wood ash and coal ash. Wood ash, if available, can be freely used anywhere in the garden. Coal ash, even when finely sifted, has a limited use, and in some parts of the garden is positively dangerous. Perhaps the best use for coal ash is on the lawn, or to serve as a foundation for a cold frame.