holds in solution. Consequently, a surface soil is generally poorer in lime, and 

 frequently in potash, than the subsoil. The complete impoverishment of the 

 soil is prevented by the presence of certain constituents which combine chemically 

 with the liberated plant food substances, and by the conservative action of vegeta- 

 tion. The plant is continually collecting from the soil and subsoil dissolved or 

 easily soluble matter, storing these in its tissues, and at its death leaving them 

 in the surface soil. But even with the best of management there is some plant 

 food leached from the soil. 



However, according to a well known law, Nature allows nothing to be lost, 

 and these leached-out materials are, through various agencies, at least partially, 

 made to accumulate in great beds of limestone, phosphatic rock and potash salts. 

 It is these accumulations of past ages that are to-day furnishing the main con- 

 stituents of fertilizers. Who knows but what the plant food which is being 

 annually leached from our fields will come into use in future ages. 



Losses of Plant Food in Crops* 



But the leaching away of plant food is not the only way in which these 

 materials are lost from the soil. The vegetable and animal produce of the land 

 are frequently consumed off the land which reared them. A partial return of 

 the plant food thus taken from the soil is made by the application of farmyatd 

 manures, but the sale of vegetables, fruit, grain, animals, and animal products, 

 the congregating of men in towns and cities, and the difficulty in employing 

 sewage with profit; and the loss of fertilizing constituents from farmyard manure 

 before it is applied to the land, all tend to make the return of the manurial con- 

 stituents to the soil incomplete. 



Some soils are naturally so rich in the elements of plant food that when the 



crops are properly rotated and "catch" crops used to economize this natural 



wealth of fertilizing constituents, it may be a long time before the soil needs 



. special manures ; but, if the land is naturally poor, or injudiciously cultivated, or 



' if special crops of like nature have to be grown year after year on the same 



ground, it may soon need some extra manure. 



On naturally poor soils it may be necessary to make a complete return of 

 all the elements of plant food removed by crops; but in most soils there is an 

 abundance of some one or more of these elements, and a partial manuring will 

 consequently suffice. With intensive farming, where thorough cultivation is prac- 

 tised, a good system of rotation followed, where little grain is sold and some 

 food is purchased in its place, and every care taken of the manure,, the land may 

 even gain in fertility. These, however, are not the conditions which exist with 

 the gardener and fruit grower, and they must of necessity purchase manure of 

 some kind. 



MANURES. 



Manures may be defined as anything that when added to the soil increases 

 the amount of available plant food in a reasonable length of time. Generally 

 speaking, they may be divided into two classes: general and simple manures. 



The general manures include farmyard manure, the various products of the 

 abattoirs, and substances of vegetable origin. These materials not only furnish 



