1 62 THE ESSENTIALS OF AGRICULTURE 



plowed. As a rule, the increase in yield gained from plowing 

 more than eight inches deep in any soil or climate does not pay 

 for the extra cost, and it is probably not advisable to plow to this 

 depth every year. The compact soils of the humid belt should 

 not be plowed deeper, perhaps, than five or six inches on the aver- 

 age. If wheat is rotated with other crops and the land is plowed 



FIG. 76. How the yield may be increased by timely plowing 



deep for the crop which precedes wheat, the depth of plowing 

 for the wheat may be less than when no rotation is practiced. 



If plowing must be done immediately before seeding, it should 

 be shallow, or else the ground will be too loose for good results. 

 Deeply plowed soil should always have ample time to settle 

 before the crop is sown. 



201. Value of timely plowing. The importance of timely 

 plowing at the proper depth is well shown (Fig. 76) by an experi- 

 ment conducted at the Kansas State Agricultural College. 1 Land 



1 Bulletin 776, Kansas Agricultural Experiment Station. 



