Agricultural Chemistry. 31<9>. 



stituents from without was of no value for his fields or for the 

 soil of England generally ; and as these manures contained the 

 constituents of the ash of wheat in the quantity required for a 

 crop, and in the proportion found by analyses to exist in the 

 ashes of the wheat plant, he maintains that his unsuccessful 

 experiments with these manures prove that the only scientific 

 basis for judging of the value of a manure, namely, its chemical 

 composition, is fallacious, and does not hold good in practice. 

 Then he tells us what his practice is. The soil, in his practice, 

 was to receive, not the same elements, and in the same propor- 

 tions, as those selected from the soil by the plant, but propor- 

 tions dictated merely by fancy, and, in a chemical sense, mix- 

 tures destitute of all principle.* 



In 1846, when Mr. Lawes made his experiments with my 

 manure for wheat, he proceeded on the impossible supposition, 

 that a field, which by a series of crops had been brought to the last 

 degree of exhaustion,! consequently after he had removed from it 

 six, eight, or perhaps ten times the quantity of mineral consti- 

 tuents required for a crop, could be brought to a maximum of 

 fertility by restoring the mineral constituents of one crop, that is 

 to say, the sixth, eighth, or tenth part of what had been removed. 

 He manured this field with 448 lbs. of the manure for wheat 

 prepared by my prescription, which contains less than half its 

 weight of the constituents of the ash of wheat ; that is, he added 

 1 grain of ash constituents for 4 cubic feet of soil, reckoning it 

 to the depth of 12 inches. And he wonders that this field did 

 not yield a maximum of produce. With this minimum of 

 manure he might keep up permanently a medium produce of the 

 field, but more than this could not rationally be expected from 

 this experiment. Had he begun by adding six, eight, or ten 

 times the quantity, and continued the experiment by adding 



896 lbs. 1350 lbs, — Journal, vol. xii. p. 19. 



Or, 300 Ihs. superphosphate of lime. Or, 350 lbs. superphosphate of lime. 



420 „ phosphate of magnesia. 325 „ phosphate of soda. 



720 lbs. 675 lbs. — Journal, vol. viii. p. 19. 



t The field selected for the purpose had been reduced to the lowest state of 

 fertility. — Journal, vol. viii. p. 7. 



