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off the premises, and the straw retained for the production 

 of manure ; and in the case of flax, that the dressed fibre 

 only is sold, and the seed retained for the feeding of cattle, 

 which is thus returned to the soil, along with the refuse of 

 the fibre or stalk, much in the same manner as the wheat 

 straw. In pursuing the inquiry, therefore, which of these 

 two crops is the more exhausting ? we must place, side by 

 side, such portion of the produce per acre of each as is 

 disposed of and lost to the land, and ascertain which of the 

 two contains the more inorganic matter, or such as is left 

 after incineration. A fair and average crop of wheat I will 

 estimate at ten loads, or thirty bushels per acre, having an 

 aggregate weight of 1,800 lbs. of grain, and a fair crop of 

 flax, when in the dressed state, at 50 stones, or 700 lbs. 

 per acre. According to Professor Johnstone's Analysis 

 of Wheat, I find that he makes the average quantity of 

 ash left, after incineration, to be 1.87 per cent. ; and, 

 according to Dr. Hodges, who has lately very minutely 

 analysed the dressed fibre of flax, I find that it yields 

 only .54 per cent, of ash. On working out the calculation 

 from these data, of the relative quantity of inorganic matter 

 which each abstracts from the soil, I find the result to be, 

 that a fair crop of wheat will take away 33.66 lbs., and one 

 of flax only 3.78 lbs. per acre, making the former about nine 

 times more exhausting than the latter. But, again, on esti- 

 mating the relative abstraction by these crops of those two 

 most important constituents of cultivated vegetables, and 

 most expensive to restore — potash and phosphoric acid — 

 I find that, according to Sprengel's analysis of wheat, that 

 while thirty bushels will abstract 4.05 lbs. of potash from 

 the soil per acre, dressed flax, according to Dr. Hodges, 

 abstracts none ; and while the former takes away .72 lbs. 

 of phosphoric acid, the latter abstracts only .25 lbs. ; — thus 



