Sulphatea—Every plant contains a quantity of sulphur, which is derived from the sulphates that are found in the soil. Sulphate of magnesia has often been applied with marked effect for turnips and potatoes, but its use does not commonly pay the expense of the application. A much cheaper source of sulphur is found in sulphate of lime or gypsum (q.v.).
Plimphate8.—The,se are largely used in agriculture. Phosphoric acid being very sparingly diffused in most soils, many plants have apparently great difficulty in obtain ing as much of this material as is necessary to rapid growth, and hence the importance of an artificial supply, which is administered in the form of phosphate of lime. The chief sources of this important element are bones (q.v.), apatite (q.v.), and guano (q.v.). The reason of its importance, and the principle which should guide its application, are explained in the article BONES AS MestritE.
1Vitrogenous Hanures.—Plants are supplied with nitrogen in the form of nitrates, or of salts of ammonia. Nitrates and the salts of ammonia promote growth in all culti vated plants when the earthy substances that enter into their composition are present, Nitrogenous manures are often beneficially applied without other substances to grain. because the grain-plants have greater facilities than the turnip for taking up phosphates and other constituents from the soil. So also, to a still greater extent, do we see the , operation of this principle in the case of grass. Having a permanent staff of roots in the soil, the plants are ready to gather up the necessary supply of mineral food when abundant nitrogenous food is presented to them, and thus nitrogenous manures of all kinds have very marked effects on grass. What determines the amount that can be profitably applied to the different cultivated plants, is simply the capability that each species possesses of expanding.under such treatment.
Farm-yard Dfanure.—This is the most valuable inanure that the farmer uses. It con tains all the elements of plants, and without its use in ordinary circumstances the fertility of the land would rapidly deteriorate. The richer the food upon which stock is fed so much the richer the manure produced. Stock fed upon straw and -water leave a very inferior manure, that requires to be largely supplemented by other materials. Turnips add largely to the value of manure, and oil-cakes of all kinds, from containing nitrogen and the earthy matters of the seeds of oil-bearing plants, produce a rich manure. Farm yard manure, under ordivary circumstances, is much more valuable for some kinds of crops than for others. The potato, for example, cannot be raised with much success imless it be supplied with this or other bulky manure having the greater number of ingre dients present. This does not appear to arise from its absolutely requiring more of any one substance than many other plants that can do far better without artificial supply. It
seems to be owing rather to a deficiency of pow-er to gather its food when dispersed through the soil. A large allowance of farm-yard manure is therefore applied to the potato when it is grown in great quantities. Tbe bean, also, is dependent on farm-yard manure more than the pea. Large breadths of turnips are often raised without farm-yard manure, as, when supplied with phosphate and nitrogen, they seem to have greater facili ties for taking up what is diffused through the soil. The weaker and poorer the soil the more important does farm-yard manure become for all plants. Farm-yard manure also. tends to render soils more adapted for carrying clovers, and many farmers always apply this to lands which are to be sown out in grasses.
Liquid Manure.—This is a favorite manure in many districts. Scotch and English farmers, in general, endeavor to have all the liquid excrements of the stock absorbed by the straw, and carried out in the solid form. On many farms, however, far more is pro duced than can be absorbed by the straw. Various modes have been adopted to apply it when this is the case. It is commonly done by a large barrel drawn by a horse; the liquid is distributed by various methods as the horse walks over the ground. The liquid manure is commonly applied to grasses, more especially to clovers or rye-grass, common or Italian. As the liquid accumulates it may be applied to the young grasses as soon as the corn crop is removed. The plants, being vigorous in autumn, absorb it, and form, roots and juices that are available as soon as the growing season arrives. It may be applied during intervals of mild. weather duringathe whole winter. It is, no doubt, most economical to apply it at the season of growth, aslhe roots take it up then very readily, and there is comparatively little waste from being washed out of the soil. In some large -establishments the whole urine is collected during the winter in large tanks, and applied in spring. This lias been done on a large scale by means of underground pipes laid over the fields, the liquid being distributed by means of a pump and hose. Steam or water power has been in some cases applied to this operation; in others it is effected by gravita tion, when the situation of steading and reservoir suits. In wet weather the liquid manure -mn be put on pretty strong, but in dry weather large quantities of water are added for the purpose of diluting it and not allowing it to injure the plants. Liquid manure is 'exceedingly rich in all the elements of plants, and is valuable for all crops; but there are -often considerable practical difficulties connected with its use and distribution.