114 TALKS ABOUT THE SOIL. 



castor pomace, dried blood, and tankage or slaughter- 

 house waste. 



We shall find phosphorus in bones of animals, 

 bone-meal, etc., mineral phosphates and the so-called 

 phosphoric fertilizers, superphosphates, etc., and in 

 foxva-manure. 



We shall find potassium in wood-ashes, potash salts, 

 and in manure. 



These are some of the names given to the commer- 

 cial fertilizers now for sale everywhere, and advertised 

 in all the agricultural papers ; and each element can 

 be found singly or combined with the others, and in 

 any proportion that you may need, in some of these 

 fertilizers. Observe this most important fact : Manure 

 contains all three, and for this reason is called a com- 

 plete fertilizer. Many of the commercial fertilizers are 

 also called complete fertilizers ; and this means that 

 they contain potassium, phosphorus, and nitrogen in 

 different proportions. 



This is the sum of this whole matter. The soil 

 becomes exhausted of certain elements. We do not 

 know which ; but by applying all three to any partic- 

 ular piece of land, we can tell very nearly which is 

 wanted. If any application produces a small effect, 

 or only increases the crop slightly, it is already abun- 

 dant in the soil, and we need apply only a little more. 

 If the effect upon the crops is marked and very plain, 

 the soil needs that particular element. Manure, we 

 shall find, always improves the soil, because it is a 

 complete fertilizer, containing all three elements, and 



