188 DRY-FARMING 
vated soils, though the direct evaporation was no 
smaller, the number of pounds of water for each 
pound of dry substance was as low as 265. 
One of the chief values of fallowing lies in the 
liberation of the plant-food during the fallow year, 
which reduces the quantity of water required the 
next year for the full growth of crops. The Utah 
experiments to which reference has already been 
made show the effect of the previous soil treatment 
upon the water requirements of crops. One half of 
the three types of soil had been cropped for three 
successive years, while the other half had been -left 
bare. During the fourth year both halves were 
planted to corn. For the sandy loam it was found 
that, on the part that had been cropped previously, 
659 pounds of water were required for each pound of 
dry matter produced, while on the part that had been 
bare only 573 pounds were required. For the clay 
loam 889 pounds on the cropped part and 550 on 
the previously bare part were required for each pound 
of dry matter. For the clay 7466 pounds on the 
cropped part and 1739 pounds on the previously bare 
part were required for each pound of dry matter. 
These results teach clearly and emphatically that 
the fertile condition of the soil induced by fallowing 
makes it possible to produce dry matter with a smaller 
amount of water than can be done on soils that are 
cropped continuously. The beneficial effects of fal- 
lowing are therefore clearly twofold: to store the 
