SUMMER FALLOW 123 



years, to be used for one crop ? It is unquestionably 

 true, as will be shown later, that clean fallowing or 

 "summer tillage" is one of the oldest and safest 

 practices of drj^-farming as practiced in the West, 

 but it is not generally understood why fallowing is 

 desirable. 



Considerable doubt has recently been cast upon 

 the doctrine that one of the beneficial effects of fallow- 

 ing in dry-farming is to store the rainfall of succes- 

 sive seasons in the soil for the use of one crop. Since 

 it has been shown that a large proportion of the 

 winter precipitation can be stored in the soil during 

 the wet season, it merely becomes a question of the 

 possibility of preventing the evaporation of this 

 water during the drier season. As will be shown 

 in the next chapter, this can well be effected by 

 proper cultivation. 



There is no good reason, therefore, for believing 

 that the precipitation of successive seasons may not 

 be added to water already stored in the soil. King 

 has shown that fallowing the soil one year carried 

 over per square foot, in the upper four feet, 9.38 

 pounds of water more than was found in a cropped 

 soil in a parallel experiment ; and, moreover, the 

 beneficial effect of this water advantage was felt 

 for a whole succeeding season. King concludes, 

 therefore, that one of the advantages of fallowing 

 is to increase the moisture content of the soil. The 

 Utah experiments show that the tendency of fallow- 



