StJBSOILERS 



113 



STJBSOILERS. 



If subsoil can be gradually worked to the top 

 it will tame without impairing the texture of the 

 earth with which it mixes. Three or four years is 

 usually required for subsoil to become nutritious 

 to roots. If turned at once to the top of the furrow 

 the change proceeds faster, exposed to air and sun, 

 but seriously retards the beneficial action of old 

 ground. There are several subsoilers on the mar- 



Subsoiler. 



ket shaped like a barbed tongue curved downward, 

 these being fastened to the heel of the share ; some 

 scrape the bottom of the furrow, and others turn up 

 a narrow groove — most of them do good work. To 

 follow one plow in the same furrow with another 

 of a narrower gauge is a simple and efficient method, 

 elsewhere explained, as the second plow throws 



