GRAIN FARMING IN" NORTH DAKOTA. 
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The harrow (fig. 9) varies in width from 16 to 32 feet, and occa- 
sionally greater widths are used. This implement is usually con- 
structed in 4-foot sections and may be made any width that is a mul- 
tiple of 4 by the addition of more sections. Four horses are used 
most commonly on widths from 16 to 24 feet, but five and six horses 
are used on the wide harrows. 
The disk harrow (fig. 10) is used generally for pulverizing cloddy 
soil. Sometimes it is used in place of a plow in preparing stubble land 
for the succeeding crop, but this practice is not common. This imple- 
ment generally consists of from 16 to 24 disks on two shafts set end 
to end, which may be set at various angles to each other by means of 
Fig. 10. — The disk harrow is an implement especially useful on packed or cloddy soil. 
levers. The most common size of disk is the 16-inch, though the disks 
vary from 12 to 18 inches in diameter. Four horses are most com- 
monly used on the disk harrow, with one man as driver, who usually 
occupies a seat on the implement. 
Grain drills (fig. 11) are ordinarily from 8 to 12 feet wide, occa- 
sionally a 16-foot implement being used. Both the shoe and the disk 
type are in rather common use. Almost invariably four horses are 
used on the drill in North Dakota. 
Rollers and packers are used to some extent, but are not necessary 
implements. They are used for pulverizing the surface and packing 
the soil into a firm seedbed. Figure 12 illustrates a type of subsurface 
packer. Four horses are normally used on either roller or packer. 
