25 

 BARLEY. 



Thirty bushels of barley the estimated product of an acre 

 of 48 Ibs. to the bushel=i440 Ibs. The straw weighs 2000 Ibs. 

 The grain and straw contain : 



Grain. 



Ammonia 33.40 Ibs. 



Phosphoric Acid. 9.64 



Sulphuric Acid 1.73 



Lime 72 



Magnesia 2.44 



Potash 6.33 



Silica 743 



Oat and barley straw are good manures, as they are rich 

 sources of nitrogen, containing, as they do, a large percentage 

 of ammonia. From this cause also, they make good fodder for 

 cattle. Only a small amount of phosphoric acid and potash is 

 required for these straws, while the amount of silica is only one 

 half of that required for wheat straw. 



POTATOES. 



One hundred bushels of potatoes, of 60 Ibs. to the bushel= 

 6000 Ibs. of tubers. The tops, when dry, weigh about 3000 Ibs.; 

 and the tops and tubers of such a crop contain : 



Tubers. 



Ammonia 21.00 Ibs. 



Phosphoric Acid 33.00 



Sulphuric Acid 12.60 " 



Lime 420 " 



Magnesia 7.80 " 



Potash 109.00 



Silica 13.00 " 



Twenty bushels of wheat require 15 Ibs. of phosphoric acid 

 for the grain, and 11 Ibs. for the straw; while 100 bushels of 

 potatoes require double this amount. Hence, two medium crops 

 of wheat exhaust only as much of this valuable element as one 

 crop of potatoes. Also, only one-sixth the amount of potash 

 required for potatoes is necessary for the wheat crop. In rais- 

 ing potatoes, few farmers supply a sufficient amount of phos- 

 phoric acid and potash. Hence, this plant and its tubers have 

 become constitutionally deteriorated on most farms, and liable 

 to speedy decay. A bushel of potatoes contains only about 

 one-seventh the amount of nitrogen contained in a bushel of 

 wheat, and its nutritive value for the production of blood and 

 muscle is in the same proportion. 



