198 THE OLIVER PLOW BOOK 



Three disks equally spaced to cut 24" wide will naturally 

 do better work than two disks spaced to cut 24" wide. 



Many insect pests of which the grasshopper is the 

 most common can be successfully fought with the disk 

 plow because of its qualities for turning hard ground. 

 It is a well known fact that grasshoppers lay their eggs 

 in nothing but hard ground. Infested fields will produce 

 grasshoppers the next year unless something is done to 

 prevent such a calamity. Whether or not a farmer expects 

 to plow the infested field in the fall he can very greatly 

 diminish the crop of grasshoppers the following year if 

 he will plow the preceding fall. There are plenty of sec- 

 tions in the United States where farmers could use the 

 disk plow earlier in the season for no other purpose than 

 this and save themselves several times the price of the 

 plow in the next crop. 



As to the draft required to pull a disk plow there is no 

 evidence to show that it pulls any lighter than a mould- 

 board plow which turns over the same volume of earth. 

 Many people deceive themselves into thinking that a 

 disk plow pulls lighter. The reason for this is probably 

 because the disk plow does not cut quite so wide a furrow 

 as the mouldboard plow. This characteristic gives the 

 disk plow an advantage over the mouldboard plow in 

 that whether one cuts a wide or narrow furrow with the 

 disk it always does an equal quality of work, whereas a 

 mouldboard that cuts either a wider or narrower furrow 

 than the width intended decreases the quality of plow- 

 ing. A too wide furrow leaves an unplowed strip and in 

 a too narrow furrow the ground is not properly pulver- 

 ized. 



The disks are sharp and placed on the frame so that 

 they present a cutting edge to the soil very similar to 



