PREPARATION OF SOILS FOR CROPS 



293 



an angle but firmly connected with the subsoil. There 

 should be as thorough disintegration of the soil as pos- 

 sible, and this can best be accomplished by the use of 

 a plow with a bold rather than too flat a moldboard. 



FIG. 48. The Furrows standing nearly edgewise (after Roberts). A good 

 way to leave fall plowed land to undergo weathering during the winter, to 

 be followed by thorough cultivation in the spring. 



Roberts states that only about 10 per cent of the energy 

 required for plowing is used by the friction of the mold- 

 board : "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 the land slide." Hence in the prepara- 

 tion of the seed bed, it is economy to secure as much 

 pulverization of the soil by the action of the plow as 

 possible rather than to leave too much for subsequent 

 treatment. The plow is the most economical implement 

 for pulverizing the land. 



