OF PLANTS BY MANURING. 71 



tant? Notwithstanding the thousands of experi- 

 mental and practical deductions respecting manure, 

 we still know nothing positive and irrefragable with 

 regard to the action of the separate elements, and 

 far less upon the question of how they comport 

 themselves in combination with each other. One 

 and the same substance may operate, moreover, 

 in two, three, four, or more ways ; its action varies 

 according to its form, as also according to the soil to 

 which it is applied, the kind of crop for which it is 

 used, and so forth. 



Although I know beforehand that in such an at- 

 tempt an extremely imperfect result can alone be 

 obtained, I will, nevertheless, essay its performance. 

 What is imperfect may possibly yield something of 

 advantage ; but from nothing at all, no benefit can 

 possibly accrue. I shall be thankful to any one who 

 will communicate his help in producing something 

 better from the imperfection which I acknowledge. 



Classification of the more ordinary Manures, 

 according to their ingredients and action. 



If in this table one and the same manure is exhib- 

 ited in several divisions, it is to be understood that 

 it is compounded of several chemical elements, and 

 may operate in several different ways. In every sep- 

 arate division the order of succession is so arranged, 

 as to display the richest manuring substances at the 

 commencement, and the poorest at the close. 



