REGULATING THE TRANSPIRATION 187 
recommended for the prevention of the direct evap- 
oration of water is of itself an effective factor in set- 
ting free plant-food and thus in reducing the amount 
of water required by plants. The experiments at the 
Utah Station, already referred to, bring out very 
strikingly the value of cultivation in reducing the 
transpiration. For instance, in a series of experi- 
ments the following results were obtained. On a 
sandy loam, not cultivated, 603 pounds of water were 
transpired to produce one pound of dry matter of 
corn; on the same soil, cultivated, only 252 pounds 
were required. On a clay loam, not cultivated, 535 
pounds of water were transpired for each pound of 
dry matter, whereas on the cultivated soil only 428 
poundswere necessary. Ona clay soil, not cultivated, 
753 pounds of water were transpired for each pound of 
dry matter; on the cultivated soil, only 582 pounds. 
The farmer who faithfully cultivates the soil through- 
out the summer and after every rain has therefore the 
satisfaction of knowing that he is accomplishing two 
very important things: he is keeping the moisture 
in the soil, and he is making it possible for good crops 
to be grown with much less water than would other- 
wise be required. Even in the case of a peculiar soil 
on which ordinary cultivation did not reduce the 
direct evaporation, the effect upon the transpiration 
was very marked. On the soil which was not culti- 
vated, 451 pounds of water were required to produce 
one pound of dry matter (corn), while on the culti- 
