248 SOILS AND FERTILIZERS 



A good seed bed cannot be made upon such a foun- 

 dation. When the land is plowed so that the furrow 

 slice is left at an angle of 30 to 45 degrees, the surface 

 is corrugated and all vegetation is buried in loose soil. 

 When land which has been plowed in this way is culti- 

 vated and harrowed, a better seed bed is formed than 

 is possible on a completely inverted furrow slice. 



Fig. 35. A poor way of plowing sod land (after Roberts). 



Fig. 36. Plowed land left in good condition for formation of seed 

 bed (after Roberts). 



In plowing, it should be the aim to thoroughly pul- 

 verize the soil, completely bury all surface vegetation, 

 and leave the land in a corrugated condition with the 

 furrow slice at an angle but firmly connected with the 

 subsoil. The plowing should cause as thorough dis- 

 integration of the soil as possible and this can best be 

 accomplished by the use of a plow with a bold rather 

 than too flat a moldboard. Roberts 16 states that only 

 about 10 per cent, of the energy required for plowing 

 is used by the friction of the moldboard: " About 35 

 per cent, of the power necessary to plow is used by the 

 friction due to the weight of the plow, and 55 per 

 cent, by severing the furrow slice and the friction of 



