CH. II.] THE ROOT. 57 



decomposed, which leads to a consideration of the 

 practice of exposing soils as much as possible, to the 

 action of the atmosphere by ridging, &c. WTien a 

 soil is tenacious, or abounding in stubborn vegetable 

 matters, as in heath lands, it cannot be too com- 

 pletely exposed to the action of the air ; but to light 

 soils, "^vhich are in general deficient in organic de- 

 composing matters, chemistry would say that ridging 

 is accompanied by e^'ils more injmious than can be 

 compensated by the benefits obtained ; for such light 

 soils are easily pulverized whenever occasion requires, 

 are so porous as at all times freely to admit the per- 

 vasion of the atmosphere ; and therefore, by this 

 extra exposure the vegetable and animal remauas are 

 hastened in decomposing, and much of their fertile 

 constituents evolved in the state of gas, or carried 

 away by the rains, &c., ^rithout there being any crop 

 upon them to benefit by them. Thus theory argues, 

 and practice certainly seems to support, in this in- 

 stance, her doctrines. Switzer, one of our horticul- 

 tural classics, says, " Rich, heavy ground cannot well 

 be ploughed too often to make it light, and the 

 better manure by killing the weeds ; as poor, light , 

 gromid cannot be ploughed too seldom, for fear of / 

 impoverishing it."' — (Ichnographia Rustica, vol. iii. 

 p. 237.) 



The benefit derivable from the access of the atmo- 

 spheric gases to the roots of plants, and the knowledge 



/ r 



I 



