FERTILIZERS. 89 



bones or dissolved bone-black ; and potash, in muriate of 

 potash or sulphate of potash. 



3. What the Crop Needs. The different crops vary 

 considerably in the relative quantity of the three ele- 

 ments needed. It is important that each be supplied 

 with a fertilizer suited to its especial wants. 



By a chemical analysis of different crops, we may learn 

 in what proportion the different elements of food are re- 

 quired in their formation, and so may obtain some idea of 

 the proportion in which these elements should be applied 

 to the soil. 



4. The Amount Required per Acre. Economy in rais- 

 ing crops, as in raising animals, requires that they shall 

 receive all the food they can consume and properly as- 

 similate. No crop can reach and thus utilize all the food 

 present in the soil; hence, more should be furnished 

 than enough to cover the wants of a single crop. At the 

 same time, a large surplus would involve waste, except 

 in soils which are able to retain it for future crops. 



Methods of Applying Fertilizers. The valuable elements 

 of most prepared fertilizers are largely soluble in water ; 

 and, as the tendency of rain is to wash these parts down- 

 ward, they should generally be mixed with the surface 

 soil. 



These fertilizers are usually so concentrated as to in- 

 jure or destroy seeds and roots when brought into im- 

 mediate contact with them. On this account, care should 

 be taken, in planting, to place some soil between them 

 jnd the sprouting seed. 



It is wiser to place them above, rather than beneath 

 the seed, so that the young roots may not be injured, 

 and so that their elements may be gradually washed 

 upon the roots as needed. 



