24 
BULLETIN 835, U. S. DEPARTMENT OF AGRICULTURE. 
The figures within the small circle.- give in liters the quantity of 
water removed from the tanks by the soil columns at the ends of 
as periods of time. 
Table 11 gives the percentages of water used in 1. 3. 5. 10. 15. and 
20 days of the total quantity used in 30 days. 
- 11.— Wat* 
from tanks by days • 7 in percentages of 
amount ren 3 J days. 
Number 
c: isr?- 
_-:•— e. 
s: 
:: 
Pa 
Per 
Per 
Per 
Pa- 
cent. 
cent. 
cent. 
cent. 
cent. 
1 
17 
22 
26 
IS 
17 
3 
30 
36 
42 
30 
29 

38 
,: 
51 
3o 
- 
10 
53 
afl 
" 
r : 
53 
15 
67 
:: 
n 
64 
67 
20 
si 
a 
86 
-.- 
a 
30 
100 
100 
100 
100 
1AC 
Table 11 shows the relatively great use of water the first few 
days of the experiment. In all cases more than one-half the total 
quantity of water used in 30 days was used the first 10 days or one- 
third of the time. From 17 to 26 per cent of the total quantity used 
in 30 days was used the first day and in two-thirds of the B0 days more 
than SO per cent of the water was used. The lighter the soil the 
smaller the relative percentage of water used the first few days, and 
the heavier the soil the greater the relative use of water during the 
first few day-. However, the lighter the soil the greater the total 
quantity that will be used in long periods of time. This is the op- 
posite of the conditions with the vertical flumes and is worthy of 
note. The heavier the soil the less extended will be the wetted area 
with the lapse of time, which condition is as would be expected. 
That is, a sandy soil or a light soil will " sub " much farther in a 
horizontal direction than a heavy soil. The results indicate also 
that a heavy soil loses more water through evaporation when the soil 
is 10 or more inches deep than a sandy soil. This can be accounted 
for from the fact that the capillarity of the sandy soil is not suf- 
ficiently great to keep the surface wetted to the optimum capillary 
capacity for evaporation. It shows also the influence of gravity 
in these horizontal flumes 10 inches in depth. Table 12 gives the 
nl g : f the total distance moved and the percentage of the total 
iter used in ; . 3 days for different periods of tune. 
