DRY-FARMING 



surface packer was simply to imitate the 

 horse-foot track in the entire field by 

 firming the lower part of the furrow- 

 slice and leaving the top portion loose to 

 form a soil-mulch. The effect of sub- 

 surface packing, therefore, is to draw 

 the moisture from the deeper strata be- 

 low, just as is the case with the ordinary 

 roller; but, further, and most important, 

 to check the evaporation of the moisture 

 from the surface by the formation of an 

 earth blanket or soil-mulch. This upward 

 passage of water brought about by sub- 

 surface packing is of the highest impor- 

 tance in the long dry periods so common 

 in western America and South Africa. 



Mr. Campbell writes : "When we reach 

 a point in the extreme heated portion of 

 the last afternoon prior to a heavy rain, 

 when our supply of moisture is beginning 

 to shorten, the fact that we have by this 

 sub-surface packing been able to lift the 

 150 



