211 



Lime, 2.9 8.5 3.7 8.3 1.8 10.9 24.6 



Magnesia, 15.9 5.0 7.7 2.8 6.4 4.3 6.3 



PotAsh, 29.5 9.2 12.9 24.5 61.5 33.7 26.6 



Soda, traces 0.3 4.4 traces 4.1 0.5 



Silica, 1.3 67.6 63.3 40.0 5.6 6.4 6.3 



Alumina, 1.0 1.3 2.1 0.5 1.2 0.3 



Moisture and loss, 2.4 3.7 .30 2.9 0.7 6.5 



100. 100. 100. 100. 100. 100. 100. 



These tables show the substances which plants extract from the soil, 

 and by their aid we can discover the quantities which are taken annual- 

 ly from a given place, and they show us that a too frequent repetition 

 of any kii.d of crop will exhaust the soil of the particular ingredients 

 which that crop absorbs. 



From these tables we may perceive that phosphoric acid and potash 

 predominate in the grain, and silica in the straw of wheat ; from which 

 facts we may learn the necessity of supplying manures containing pot- 

 ash and i)hosphoric acid, and keeping our straw at home, and manufac- 

 turing it into manure. 



These tables point out the necessity for a rotation of crops, as they 

 show that green crops differ essentially from grain crops, in the ma- 

 teriuU theij extract from the soil. 



A jiidic ous rotation of crops, is one of the most important arrange- 

 ments in agriculture. In wheat growing it is essentijilly necessary to 

 the success of the crops. 



If we continue to sow wheat in the same field year after year, the 

 soil will be exhausted, weeds will ripen and sow their seeds, and our 

 crop Ktajved for want of proper food, or choked with weed?, or devour- 

 ed with insects, will not be worth the labor of harvesting. 



PRODUCE OP WHEAT. 



It is sufficiently plain that a very large crop of wheat cannot be 

 raised, even off our richest land, in America, without the addition of 

 powerful manures such as guano, bone dust, or nitrate of soda. 



Few farmers are aware of the number of bushels of wheat that it is 

 possible to raise, off an acre of land. 



A farmer in England grew 90 buehels on an acre, by using salt, in 

 addition to barn-yard dung; but thin ii> not as uo«ommon quantity. In 



