60 IRRIGATION PRACTICE 



the whole virtue of cultivation lies therein. However, cul- 

 tivation has other beneficial effects quite as important as 

 the direct saving of soil moisture. The loosening of the 

 top soil permits the entrance of the atmosphere, with 

 the free exchange of gases between the atmosphere and 

 the soil air, which ventilates the soil and enables various 

 physical, chemical and biological changes to take place. 

 The result is of the highest importance to plant life. The 

 condition of the top soil, the part turned by the plow and 

 stirred by the cultivator, is of first importance in all 

 agriculture. A striking illustration of this other value 

 of cultivation was secured in the Utah work. In a series 

 of tests designed to show the moisture-saving possibili- 

 ties of cultivation, a very careful account was kept of the 

 total yield of dry matter produced under the various soil 

 treatments. Corn was grown on four different soils vary- 

 ing from a coarse sand to a fine clay, and from high fer- 

 tility to great infertility. The following are some of the 

 results obtained: 



POUNDS OF WATER TRANSPIRED FOR ONE POUND OF DRY MATTER 



In every case, excepting the abnormal infertile sand, 

 the careful stirring of the soil enabled the plant to pro- 

 duce one pound of dry matter with a smaller quantity 

 of water than when the soil was not cultivated. The 

 sandy loam was of a self-mulching nature, and really 

 lost water by cultivation, yet on this soil, also, cultiva- 



