54 
Research Bulletin No. 5 
It will be noted from Tables 20 and 21 that in most cases 
a rather distinct break is shown in the water content at harvest 
time at some depth. Take for example oats. There is in every 
case a more or less wide break in the amount of water at harvest 
time between the fourth and fifth foot-sections. In fact this is 
generally true of all spring small grain crops. The break ap- 
pears in the record to be abrupt. This is not quite true in the 
field, but is due to the method of taking the samples. The 
samples are taken in foot-sections and the break appears to 
come abruptly between them. If the samples were taken in 
inch-sections a gradual lessening in water content would be 
found to extend thru several inches. This rather abrupt break 
in water content seems to indicate the feeding depth of the roots. 
A sufficient number of roots go down to this point to take out 
most of the available water. There are frequently indica- 
tions of loss of water from the section just below the drier soil. 
A few roots may have entered this lower depth and used some 
water, or the loss may be due to some water having moved by 
capillary action into the feeding zone of the roots. The amount 
of this water used by the roots from the lower depths is very 
small. 
It will be noted in the tables that the first foot and even the 
second foot sometimes show considerable water at harvest. This 
water has been retained from rains coming after the crop ma- 
tured and was not left there by the growing crop. The soil 
sampling marked "harvest" has not in all cases been taken im- 
mediately after harvest but has been taken before any water had 
reached the lower depths. In some cases a rain would come be- 
fore the crop was off the ground, but after it had matured. In 
the column showing average moisture content of each foot-sec- 
tion at harvest, the amount of water in the first and second foot 
cannot therefore be taken as the limit to which the moisture was 
reduced when the crop had matured. This is especially true of 
winter wheat and corn. These amounts were obtained by aver- 
aging the amount of water at harvest in that foot-section for all 
the years. 
From Table 20 it will be seen that oats, spring wheat, and 
barley feed to a depth of four feet or a little more. In some 
cases, as spring wheat in 1910. the available water has been 
used from the fifth foot. Taking the average, however, it shows 
the fourth foot dry and the fifth rather moist. Table 21 shows 
that corn does not take out as much water as do the small grain 
crops. This is probably due to the lesser number of plants on a 
