148 PRODUCTION OF A NEW SOIL. 



no less than thirty feet in diameter, or three times 

 as great in breadth as the height of the tree. How 

 perfectly futile the attempt to benefit such a broad 

 surface by spading a circle two or three feet in 

 diameter, which would be but a hundredth part of 

 the whole area of the branching fibres ! " 



The importance of an extensive plant-pasture 

 has been proved by the previous examples. Deep, 

 thorough pulverization of the soil is absolutely 

 essential to the growth and success of trees, and 

 their fruit shows clearly whether or not this fact 

 has been regarded. 



2. Deep cultivation introduces a fresh virgin soil 

 from below into the old, exhausted earth above ; and 

 frequently lands which are unproductive have a 

 subsoil of great wealth. Rains which have perco- 

 lated through the surface have carried to the under 

 soil the fertility which they themselves contained, 

 and much of that which was before held in the 

 upper ; and, by turning and composting them, a 

 soil which has never been disturbed, rich in those 

 substances which the atmosphere elaborates into 

 food for vegetable life, is brought up for use. But 

 in some localities the subsoil contains those prop- 

 erties which are decidedly noxious to plants, and 

 therefore the immediate mixture of these with the 

 arable earth would be an injury. When fertilizing 

 substances from beneath are added to the surface 

 mould, the effect is of course beneficial ; but when 



