SOILS AND FERTILIZERS 407 



The sole object of agriculture is the production of such plants 

 as contribute to the satisfaction of the wants of mankind. The soil 

 constitutes a magazine of the materials of crop production. The 

 whole range of vegetable production embraces fourteen elementary 

 substances; but not all of these fourteen are necessary to every 

 species, nor to the same species under all circumstances. All of 

 these substances are to be found in all soils in various forms and 

 degrees. 



It is the business of the farmer, by the various processes of 

 cultivation, to combine these several elements in the production of 

 such crops as he proposes to make. Every plant is its own chemist, 

 with the soil for its laboratory, and may be implicitly trusted to take 

 care of itself, if the materials in a condition suitable to serve as food 

 are placed within the reach of its roots. The amount of the several 

 elements that are withdrawn from the soil by the plant are exactly 

 represented by the crop, just as a piece of cloth represents the cot- 

 ton, or other material out of which it is made. The first inquiry 

 which addresses itself to the farmer who proposes to increase the 

 product of his land by the use of fertilizers is, what is the most 

 economical means of effecting this object. 



The great competition in all industrial pursuits, and in farm- 

 ing not less than in others has narrowed the margin for profits to 

 such an extent as to render success dependent upon judicious, and 

 especially upon the economical employment of means. Thrift in 

 farming will be found largely dependent upon the use of home- 

 made fertilizers; chief among which is barnyard manure. This 

 can be most easily and economically applied after haying been com- 

 posted with such other waste material as may be available. 



The efficacy of barnyard manure depends upon precisely the 

 same elements as are offered to the farmer in the various chemical 

 fertilizers the chief constituents in all being phosphoric acid, nitro- 

 gen and potash. These three elements are required by different crops 

 and different soils in very different proportions. Whilst they are all 

 present in barnyard manure, yet they exist in proportions very dif- 

 ferent from that in which they are required by the several crops 

 which are most commonly produced with us. 



The fertilizing value of barnyard manure, as of any material, is, 

 however, not determined exclusively by the total amounts of nitro- 

 gen, phosphoric acid, and potash it contains, but depends to a very 

 large extent upon the ease with which these constituents are utilized 

 by the plant, that is, upon their availability. 



Barnyard manure is the most important manurial resource of 

 the farm and should be carefully saved and used. It represents fer- 

 tility which is drawn from the soil and must be returned to it if pro- 

 ductiveness is to be maintained. It not only enriches the soil with 

 the nitrogen, phosphoric acid, and potash, but it also renders the 

 stored-up materials of the soil more available, improves the mechan- 

 ical condition of the soil, makes it warmer, and enables it to retain 

 more moisture. 



