no SOILS AND FERTILIZERS 



farmer has in each ton of the waste product from his 

 stock $2.78 in fertilizing value to restore his land, with 

 no expense except the labor of caring for it and applying 

 it. This last expense would have to be borne in hauling 

 it away if not used, so this need not enter into the cal- 

 culation. Taking into consideration these figures, it 

 seems scarcely credible that farmers will give away or 

 sell their manure to more thrifty neighbors or so neglect 

 to protect it that it loses a large percentage of its nutri- 

 tive soil value. Yet many farmers still continue this 

 wasteful, improvident practice, and then purchase com- 

 mercial fertilizers when their land has become infertile. 



Commercial Fertilizers. -- The materials for making 

 these fertilizers are the by-products of the slaughter 

 and meat-packing houses, like bone meal, dried blood, 

 or tankage (waste material) ; natural products of the 

 earth that are mined, like Chile saltpeter (sodium ni- 

 trate), phosphate rock, kainit (a mineral composed of 

 magnesium sulphate, potassium sulphate, and magnesium 

 chloride found in Germany) ; by-products of gas and 

 coke manufacture (ammonia sulphate) ; or vegetable 

 products, like wood ashes and tobacco stems. 



The value of the commercial fertilizers has nothing 

 to do with their origin, but depends entirely upon the 

 quantity and the form in which the plant food exists 

 in them, whether in soluble form and directly available 

 to the plant or in a form which must first be acted 

 upon by other agencies before being used by the plant. 

 (See page 107.) 



Amounts to Use. Commercial fertilizers are used 

 for the same purpose as manures to restore or maintain 

 the fertility of the soil. Most authorities are agreed 

 that each acre of land, in order to show the maximum 



