38 CAMPBELL'S SOIL CULTURE MANUAL 



vation," instances where the early use of the disk for the 

 sole purpose of preventing evaporation and preparing the 

 surface to receive and utilize further rains, has resulted 

 in giving the farmer increased yields of corn as high as 

 twenty bushels to the acre. Think of twenty bushels of 

 corn per acre for only forty cents of extra expense. In 

 the handling of fields for summer culture there is no tool 

 that can take the place of the disk harrow, cost of labor 

 and value of work considered; and while it is not a tool 

 that can be continuously used, we do not see how a man 

 can successfully handle an orchard without it. The disk 

 harrow may be used to prepare a field for a crop, and 

 in connection with the plow, its work is most valuable. 

 The complete pulverizing and thorough separating of the 

 particles one from another in its rotating action, when 

 proper diameter of disk is used, is perfect. 



WHEN TO USE THE DISK. 



We most urgently advise the use of the disk early 

 in the spring on all stubble ground or old fields intended 

 for spring crops. The value of this early work with the 

 disk is inestimable, and the more arid the condition, the 

 greater the value of its early use. No time should be 

 lost after the soil has become sufficiently thawed and dry 

 so that it will not stick to the disk. For best results 

 double disk the ground by lapping one-half, the object 

 being to thoroughly pulverize and loosen the surface for 

 a two-fold purpose. To loosen and form a soil mulch to 

 prevent the loss of moisture by evaporation as well as 

 to break the hard crusted surface to promote a more rapid 

 and complete percolation or soaking into the soil below 

 of the early spring rains. 



In addition to the subject of conserving and more 

 effectually storing the moisture, is another question not 



