488 



THE PRINCIPLES OF SOIL MANAGEMENT 



Another form of roller is the sub-surface packer. One 

 type of this implement consists of a series of wheels with 

 narrow V-shaped rims, which press into the soil and com- 

 pact it, while leaving the surface loose. (Fig. 67.) They 

 are designed primarily to level the land after plowing, 

 and to bring the furrow slices close together and in good 

 contact with the subsoil, in order to conserve moisture 



Fig. 148. Potato digger which is also very effective in stirring the soil. 



and promote decay of organic material, which may be 

 plowed under. This implement has been developed 

 chiefly in semi-arid and arid sections of country where 

 the conservation of moisture is especially important, 

 but they might well have a much larger use for the same 

 purpose in those sections of the country which are sub- 

 ject to late summer and fall droughts. While compacting 

 the soil, these implements leave a mulch behind. 



