174 IRRIGATION AND DRY FARMING 



at the inner part, and is slanted two and a half inches to a 

 sharp outer edge. A weight of about five hundred pounds 

 is so placed as to make these wheels sink well into the ground, 

 packing the soil quite firmly beneath the surface and leaving 

 the surface itself loose and mellow. A mulch (page 53) is 

 thus formed which reduces evaporation to the least possible 

 amount. After the crop is planted, the soil is kept loose at 

 the surface until the crop is matured. The moisture pre- 

 served through one year by this system is often sufficient 

 for the maturing of crops through three or four following 

 years. If practiced in moist regions during dry years, this 

 system would add greatly to the yield. 



The principles of dry farming might be put to good use 

 in both the arid regions of the West and those regions where 

 there is a good winter rainfall. In the former areas, where 

 land can be flooded, one application of water would be 

 enough for an entire season. In ( regions having a winter 

 rainfall, the moisture could be so preserved that irrigation 

 would be wholly unnecessary, and heavy yields would 

 result each year. 



QUESTIONS AND EXERCISES. 



1. What are arid regions? 



2. What are the chief methods of applying water in 

 irrigation? 



3. Describe the furrow method of irrigation. 



4. What is dry farming? By what methods is it carried 

 on? 



5. Describe a subsurface packer. 



