16 DRY FARMING IN RELATION TO RAINFALL AND EVAPORATION. 



These results indicate that a fine surface mulch on summer-tilled 

 land, while ideal in preventing evaporation, packs during a torrential 

 rain and so fails to absorb the water freery. A rough, uneven, lumpy 

 surface, including stubble, with finer soil beneath, is preferable under 

 such conditions to a fine surface mulch. The rough surface material, 

 combined with the finer soil below, still makes an effective mulch. 

 During windy, dry weather, the rough, lumpy surface will protect 

 the soil from blowing. During a torrential rain the rough sur- 

 face will tend to prevent the soil from washing, and by holding the 

 water to some extent will make the soil below absorb more. The 

 treatment of the land so as to absorb all of the rain that falls is a 

 matter of great importance to the dry farmer. This subject is now 

 being given special attention at the experimental farms of the Office 

 of Dry-Land Agriculture Investigations." 



HAIL. 



» 



Hail is one form of precipitation that is the dread of every dry 

 farmer. Hailstorms are likely to occur in almost am- portion of the 

 Great Plains during the summer months and frequently do great 

 damage to standing grain. These storms take place somewhat more 

 frequently in the southern parts of the area, and in some districts 

 seem to occur more often along the river courses and valleys than 

 upon the table-lands. They do occur, however, on the table-lands 

 and divides, and their path is generally narrow and very sharply 

 defined, the hail sometimes completely destroying standing grain in 

 part of a field and leaving the remainder uninjured. About the only 

 precaution that the prospective settler can take is to try to avoid 

 locating in regions which are known to be in the track of such storms. 

 The grain should also be cut at the earliest possible date. Other- 

 wise, the dry farmer must take his chances upon the occurrence of 

 hail just as he must upon the occurrence of unusually dry weather. 

 Many new settlers who feel that they can not afford to risk the loss 

 of their crop insure against hail just as they insure against loss by 

 fire. Established fanners as a rule find that it pays to carry their 

 own insurance. 



EVAPORATION IN DRY-FARMING SECTIONS. 



The rate at which evaporation takes place in any given region has 

 a marked influence upon the quantity of rainfall necessary for suc- 

 cessful dry farming. The accompanying map (fig. 4) shows the 

 evaporation taking place from a freely exposed water surface during 

 the six summer months in different parts of the United States. The 



"See article entitled "Dry-Land Farming in the Great Plains Area," by E. C. 

 Chilcott, Yearbook of the U. S. Dept. of Agriculture, 1907. 

 188 



