92 



AMERICAN MANURES. 



Grain. 



Ammonia 34-05 Ibs. 



Phosphoric Acid 13-65 



Sulphuric Acid 7'50 ' 



Lime 1*05 



Magnesia...* 2-25 



Potash 8-55 



Silica 7-80 



By comparing the above Table with the one 

 giving the composition of wheat, the reader can 

 understand why larger continuous crops of rye 

 than of wheat can be raised from the same soil ; 

 because rye does not require so much of those 

 elements which are first exhausted in soils as 

 wheat does. In like manner, by studying the 

 composition of different crops, and noting the 

 amounts of the different elements required to 

 produce them, we can understand why farmers 

 should have a dollar for a bushel of wheat, when 

 corn is selling at fifty cents, and rye at seventy- 

 five. Such an examination shows that the 

 quantity, and consequently the price of any crop, 

 are naturally regulated by the amount of certain 

 valuable substances required for its production. 



OATS. 



Fifty bushels of oats the estimated product 

 of an acre of 33 Ibs. to the bushel = 1650 Ibs. 

 This amount of grain requires about 2000 Ibs. 

 of straw. The grain and straw contain : 



