472 
Journal of Agricultural Research 
Vol. XIV, No. II 
the loss from below the first few inches was, like that in the grass field, 
quite uniform, as may be seen from the data for August 3 and 28; but 
the ratios did not fall as low, 1.7 being the minimum. Whether a severe 
drouth near the end of the growing season would have induced in the corn¬ 
field ratios as low as those found in the grass field earlier in the season can 
not be decided from the data, but it should be pointed out that in the 
latter part of August, when the corn was making the heaviest Remands 
upon the soil moisture, the ratio in the lower half of the surface foot of 
even the grass field did not fall below 1.5, while on August 28 it was 1.8 in 
the cornfield, compared with 1.7 in the grass field. 
On the exposed subsoil, with a smooth compact surface without a 
soil mulch, such as existed in the fallow, the effect of evaporation ex¬ 
tended a little deeper, a ratio as low as 1.4 being found in the fourth 
inch on July 9, and ratios below 1.0 in the first three i-inch sections. 
Below the fourth inch the ratios were quite uniform throughout the 
season from level to level, the average for the second 6-inch section vary¬ 
ing only between 2 and 2.2, except after the heavy June rain, when it 
rose to 2.3. In general the ratio was 0.6 or 0.7 lower than that for the 
corresponding section in the fallow. 
depth of penetration of rains 
« 
The depth of penetration of the water from different rains (Table XIV) 
is indicated by the distance from the surface to which the ratios were 
increased. In the fallow this was only roughly proportional to the 
amount of rain, but here the moistness of the soil below the uppermost 
3-inch section was comparatively constant. Only two rains were suffi¬ 
ciently heavy, those of June 12-13 and August 16, to affect the twelfth 
inch and only the first of these two gave any evidence of having caused 
an addition of moisture to the second foot of soil. The low ratios found 
on August 29 in the levels below the first foot (Table XIII) support 
this conclusion. The June rain caused the passage of water into the 
second foot in the grass field also, but that of August 16 affected the 
moistness to only 10 inches. The much lesser penetration of the various 
rains in the exposed subsoil is to be attributed to the run-off from the 
smooth, hard, gently sloping surface before much of the water had time 
to enter the soil. 
The actual addition of water to the soil of the first foot, as computed 
from the increase in moisture content and the relative density of the soil 
(Table III), amounted to nearly 90 per cent of the rainfall in the case of 
the grass fields, but to only about half as much in the fallow. Most of 
this difference must be regarded as an actual loss through run-off, as in 
the case of only one rain, that on June 12-13, can any part of it be attri¬ 
buted to a portion of the water having passed through the first into the 
second foot. 
