20 BULLETIN 1139, TJ. S. DEPARTMENT OF AGRICULTURE. 
The differences in the number of eases in the different foot sec-' 
tions are in a large measure the result of the limitation of sampling 
due to the limitation of depth of feeding in certain soils. If the 
samples had all been taken to a depth great enough to make the 
table entirely symmetrical, the condition of the sixth foot would have 
been expressed by the symbols OW or OD in nearly all of the 63 
cases when determinations were made in the first foot section but not 
in the sixth. 
Consideration of the table will be confined largely to the portion 
where the results are expressed as percentages. The most striking 
feature of the table is the closeness with which plats A and B ap- 
proximate each other. In the first foot of soil both were filled to 
capacity, and all of the water was used about three-fourths of the 
time. About 10 per cent of the time the soil was not entirely filled 
with water at any time during the growing season, but all available 
water was used. In only 1 per cent of the time, which represents 
the year 1915 at North Platte, was the soil filled with water at 
harvest. There has never been a case where no available water was 
present in the first foot during the growing season. In one year, 
1911. at Belle Fourehe, very little available moisture was present in 
the first foot of plats A and B. This year was necessarily omitted 
in Table 1, as the soil was so dry that the wheat did not come up. 
Summing up the results for the first foot, it is found by adding the 
percentages under the symbol PD to those under the symbol F that 
the available water in both plats A and B was entirely depleted 
at harvest in 89 per cent of the cases studied : the water content was 
reduced but not entirely exhausted (the condition represented by 
the symbol PTT) in 10 per cent of the cases; and the soil was still 
full of water at harvest time (classed as the condition T »T) in 1 per 
cent of the cases. 
The second foot section of plats A and B, when compared with 
the first, shows a sharp reduction in the number of times full use 
of water was made (F). This is accounted for by the great increase 
in the percentage of cases when the soil was only partly filled with 
moisture and all of it used (PD) and in the appearance of a few 
cases where the soil was dry all the season (OD) . The proportion of 
the time that moisture present in the soil was only partly used (PW) 
remains nearly constant. 
Summing up the results for the second foot section, it is found 
that it was dry at harvest 89 per cent of the time on plat A and 87 
per cent of the time on plat B. This is the sum of the percentages 
under symbols F, PD, and OD. The moisture content was reduced 
but not exhausted in 10 per cent of the cases on plat A and in 13 per 
cent of the cases on plat B. This condition is represented by the 
symbol PTT. There was only 1 per cent of the time on plat A when 
the moisture content of the soil was not reduced when available 
moisture was present. This is the condition shown by the symbol 
OW. All of the available water in the second foot of the two 
plats was removed practically the same proportion of the time as 
in the first foot. The aggregate quantity of water obtained by the 
wheat crop from the second foot must have been considerably less 
than that obtained from the first foot, as it has been filled with water 
less frequently. 
