SOIL MANAGEMENT 



15 



It works to greater depth and tends to bring Imiips and stones 

 to the surface and to collect roots and vines. Usually the slant of 

 the teeth of the spike- and spring-tooth implements can be 

 readily adjusted, and this determines the extent to Avhicli they 

 stir the soiL 



Something more vigorous than a harrow is sometimes required 

 on lumpy soil; grinding and crushing action is most effective. 

 For pulverizing and leveling the surface, the plank drag is 

 effective. 



Fig. 7. — The plank drag smooths and levels the surface. An efficient home-made 

 implement. — Bi/ permission of Dunham Co., Berca, Ohio. 



The most common tool used to pack the soil is the roller, of 

 which the log roller is the pioneer type. The value of the roller 

 depends largely on its weight and diameter. For the same 

 weight the smaller diameter is more efficient than the larger 

 diameter. The roller is often used immediately after plowing 

 to press doA\Ti the furrow slices so that thej^ Avill not be torn up 

 by the harrow and so that a more level surface is provided for 

 the team. In countries where the winters are severe and the 

 roots of plants are torn loose from the ground by frost, the roller 

 is used in order to press roots into the soil and to firm the soil 



