CHEMICAL MANURES. 69 



Azote, 276 Ibs., equivalent in harvest to 552 Ibs. 



Phosphoric acid 106 " 



Potash 99 " 



Lime 276 " 



The four harvests of colza and wheat contain 



Azote 524 Ibs. 



Phosphoric acid 108 " 



Potash 239 " 



Lime 249 " 



This time, if we make the balance, a grave fact strikes us. The 

 earth is decidedly the loser in two points, potash and phosphoric 

 acid: 



Fertilizer. Harvest. Loss. Gain. 



Azote 552 Ibs. 524 ... 28 Ibs. 



Phosphoric acid 106" 108 2 Ibs. 



Potash 99 " 239 140 " 



Lime 276 " 249 ... 25 " 



There is here no illusion ; the earth is decidedly in deficit. The 

 fertilizers proposed are insufficient, and their continued use would end 

 in injury to the fertility of the soil. Nevertheless, in reality, these fer- 

 tilizers are sufficient, and the land is not wasted. These apparently 

 contradictory facts are easy to reconcile. To simplify the discussion, 

 I admit that the preceding culture is done by hand, and that straw 

 and grain are sold. Gentlemen, you are not ignorant of the fact that 

 though the wheat straw may find a ready sale, it is not the same with 

 the straw and husks of the colza, which have no commercial value, 

 and which it is sometimes almost impossible to dispose of. Under 

 these circumstances it is natural to seek a use for them. Suppose we 

 burn them and spread their ashes over the soil. The earth will thus 

 recuperate more in potash and phosphoric acid than is necessary to 

 compensate for the deficit. 



This restitution, consequently, immediately shifts the balance. 

 The earth was the loser, and now, on the contrary, receives an excess. 



To show you how the remains of the harvest that are without com- 

 mercial value can acquire an importance as a source of fertility, 

 permit me to show you the composition of two harvests of colza, and 

 to make over our balance, while the straw and husks have been 

 burned on the soil and only the grain exported : 



Composition of Two Harvests of Colza. 



Harvests. Azote. Fhos. acid. Potash. Lime. 



Straw, 20,656 Ibs. 21,480 Ibs. 30,980 Ibs. 6,628 Ibs. 19,924 Ibs. 

 Husks, 9,216 " 10,376 " 1,916 " 29,408 " 28,904 " 

 Grain, 9,356 " 39,192 " 12,028 " 6,648 " 3,040 " 

 Balance rectified by burning the straw and husks of colza. 



Fertilizers. Taken off by harvests. Gain to soiL 



Azote 1244 Ibs. 1180 Ibs. 6.4 Ibs. 



Phosphoric acid 240 " 218 " 22 " 



Potash 224 " 178 " 46 " 



Lime... 624 " 76 " 548 " 



