... its form injured. Roots are turned aside by a hard sub-soil, as they would be if received by the surface of a plate of glass. SUB-SOIL PLOWING Describe the Mapes plow. Why is the motion ... as hoeing, plowing, etc.[AN] principle, the sub-soil plow renders the compact lower soil sufficiently fine for the requirements of fertility.[Pg 234] Why are the benefits of sub-soiling ... depth of two feet or more. The sub-soil plow is coming rapidly into use. There are now in New Jersey more foundries casting sub-soil plows than there were sub-soil plows in the State six years...