644 
Journal of Agricultural Research 
Vol. V, No. 14 
TRANSPIRATION AS DETERMINED BY RADIATION AND SATURATION DEFICIT 
Corresponding graphs based upon vertical radiation and saturation 
deficit are also given in figure 21. The values for the latter term are 
computed from the mean hourly wet-bulb depression and the corre¬ 
sponding hourly air temperatures. The resulting equations follow: 
For rye.0.455 R v +0.622 D=T; 
For alfalfa.0.538 i^+0.553 D=T; 
For amaranthus...0.538 R v + 0.481 D=T; 
in which D represents the saturation deficit expressed as a percentage of 
Fig. 22.—Graphs showing the observed evaporation with that com¬ 
puted by least-square methods from the vertical component of 
radiation and the saturation deficit. 
the maximum, and the other symbols have the same meaning as before. 
An inspection of the graphs shows them to be similar in form to those 
computed from radiation and temperature The coefficients are also 
