THE PROPER DEPTH. 141 



ficiently moved and pulverized ; and we all know 

 that clover roots descend very deeply into good 

 friable subsoils. The pan, or impervious mass that 

 is often formed immediately below the plough, is a 

 great im23ediment to the roots of plants ; but sub- 

 soiling remedies this evil. It often requires great 

 force to break up this pan ; but the advantages 

 accruing from subsoiling such lands as I have 

 described, are observable for several years. One 

 result of deepening the staple is, that it causes a 

 less rapid but more perfect development of the 

 plants; their growth is prolonged, and forms a 

 striking contrast to the hasty prematurity and 

 inferior produce of shallow soils, which have a hard 

 and unpulverized substratum. 



" Another advantage of subsoiling is the destruc- 

 tion of deep-rooted weeds. I know of instances 

 where the roots of thistles and other obnoxious 

 plants, as thick as one's finger, have been disturbed 

 by the fork and in subsoiling, which were merely 

 pruned by the ordinary plough." 



Depth of imlverization. As was noticed under 

 the last head, the more we gain in the depth of 

 fertile soil, the more valuable does our land become, 

 because the root-pasture is increased. It is impos- 

 sible to go too deep as long as we do not interfere 

 with the drains. The usual number of inches of 

 cultivation is from twenty-four to thirty-six. The 



