CEREAL CULTIVATION GREAT PLAINS 361 



surface packer, of which the former is more common. 

 The surface packer has its wheels flat or nearly so, and their 

 edges deeply notched (Fig. 112). The effect of the use of 

 this implement is to leave the surface compressed and 

 pulverized but not smooth. The subsurface packer has 

 wheels disk-shaped or, in cross section, V-shaped, and 



FIG. 112. Surface packer or Dunham roller. 



its pressure is therefore exerted beneath the surface (Fig. 

 113). 



In the North the packer is commonly used after the seed 

 is sown, the usual order being seeding, harrowing, pack- 

 ing. Some, however, use it only before drilling. In the 

 cases of fall plowing and summer tillage, it is often recom- 

 mended that the packing be done at once after plowing, 

 followed by the harrow, particularly when the subsurface 

 machine is used. This procedure is not followed, however, 

 in Canada, and apparently is not common in the United 



