OF SOIL AND MANURE. 331 



CHAPTER XX. 

 OF SOIL AND MANURE. 



Notwithstanding all that has been written upon 

 these substances, and the endless accounts we possess 

 of their real or supposed action upon vegetation, I 

 must confess that the contradictions are so numerous, 

 the exceptions to .supposed rules so frequent, and phy- 

 siology is so insufficient to account for the greater 

 number of well ascertained facts, that it does not 

 appear to me possible to construct any tolerable 

 theory relating to them.* 



Mr. Knight has observed that varieties of the same 

 species of fruit tree do not succeed equally in the 

 same soil, or with the same manure : the Peach in 

 many soils acquires a high degree of perfection, 

 where its variety, the Nectarine, is of comparatively 

 little value; and the Nectarine frequently possesses 

 its full flavour in a soil which does not well suit the 

 Peach. The same remark is also applicable to the 

 Pear and the Apple ; and, as defects of opposite 

 kinds occur in the varieties of every species of fruit, 

 those qualities in the soil which are benefioial in some 

 cases will be found injurious in others. In those dis- 



[* Tliese remarks were perfectly applicable when this work was 

 pulilishe 1 (early in 1840); but the treatise on Organic Cliemiatry in 

 its applications to Agriculture and Physiology, by the distinguished 

 Professor Liebig, which appeared a few months later, has greatly 

 elucidated the whole subject] 



