THE PLOW AS A TILLAGE IMPLEMENT 



473 



sod plow. Since the steep moldboard or fallow-ground 

 plow exerts the most force on the soil in a given time 

 at a given speed of movement, it follows that if a 

 particular soil is over-wet it should be plowed with 

 the sod-plow, while, if it must be plowed when too dry, 

 the fallow-ground plow will be more effective, disre- 

 garding the draft which will probably be large in the 

 latter case. 



Fig. 132. Six-gang plow. Usually operated by steam engine. Adapted to 

 large, level areas of uniform soil, relatively free from stone. 



There is a general relation between the width of the 

 furrow-slice and its depth. In general, it may be said 

 that this ratio is about two in width to one in depth. 

 The greater the depth, the less in proportion may he 

 the width of the furrow-slice. 



On clay soil in particular, there is also a relation 

 between depth and condition. A wet soil should be 

 plowed more shallow, other things equal, than a dry soil, 

 because the puddling action is less. On a dry soil, the 

 depth should be increased, to increase the pulverization. 



