PREPAKATION OF THE SOIL. 55 



plant down we must starve and curtail its roots as 

 Avell as use the pruning-knife on its branches. 



There are two methods of deepening a soil, viz : by 

 the subsoil plough and by trenching with the spade. 

 Both these operations are too well known to require 

 a minute description, though in regard to the latter 

 there are so many and such contradictory directions 

 given in books that we may be pardoned a few re- 

 marks in relation thereto. 



In order properly to trench a piece of ground the 

 directions given by Loudon are as explicit and judi- 

 cious as possible. " Trenching is a mode of pulveriz. 

 ing and mixing the soil, or of pulverizing and chang- 

 ing its surface to a greater depth than can be done 

 by the spade alone. For trenching with a view to 

 pulverizing and changing the surface, a trench is 

 formed like the furrow in digging, but two or more 

 times wider and deeper; the plot or piece to be 

 trenclied is next marked oif with the line into parallel 

 strips of this width ; and beginning at one of these, 

 the operator digs or picks the surface stratum, and 

 throws it in the bottom of the trench. Having com- 

 pleted with the shovel the removal of the surface 

 stratum, a second, third or fourth, according to the 

 depth of the soil and other circumstances, is removed 

 in the same way ; and thus, when the operation is 

 completed, the position of the different strata is 



