82 M ANURES. 



together without having everything present that is 

 necessary. Before he can work to the best advan- 

 tage, he must know what manures are composed of, 

 how they are to be preserved, where they are needed, 

 and what kinds are required. True, he may from 

 observation and experience, guess at results, but he 

 cannot know that he is right, and that he gets his re- 

 sults in the cheapest and most economical way, until 

 he has learned the facts above named. In this section 

 of our work, we shall endeavor to convey some of the 

 information necessary to this branch of practical 

 farm ing. 



We shall adopt a classification of the subject some- 

 what diiferent from that found in most works on 

 manures, but the facts are the same. The action of 

 manures is either mechanical or chemical, or a com- 

 bination of both. For instance : some kinds of ma- 

 nure improve the mechanical character of the soil, 

 such as those which loosen stiff clay soils, or others 

 which render light sandy soils compact these are 

 called mechanical manures. Some again furnish food 

 for plants these are called chemical manures. 



Many mechanical manures produce their effects 

 by means of chemical action. Thus potash combines 

 chemically with sand in the soil. In so doing, it 

 roughens the surfaces of the particles of sand, and 

 renders the soil less liable to be compacted by rains. 

 In this manner, it acts as a mechanical manure. The 

 compound of sand and potash,* as well as the potash 

 alone, may enter into the composition of plants, and 



* Silicate of potash. 



