60 
WATER REQUIREMENT OF PLANTS. 
KINGS EXPERIMENTS. 
King (1905) measured the water requirement of corn in several 
different places in the United States. (Table XV, p. 27.) Different 
types of soil were employed, and the differences in the water require- 
ment can not therefore be entirely attributed to varying climatic 
conditions. 
VON SEELHORST S EXPERIMENTS. 
In his experiments with pasture and grassland plants Von Seelhorst 
(1910) found that the water requirement varied greatly at different 
periods of the year. His results (Table LIX, p. 69) show that the water 
requirement of the pasture crop was the lowest from April 1 to May 16; 
from May 16 to June 20 it was 58 per cent higher; from June 20 to July 
29, 350 per cent higher; and from July 29 to September 16, 110 per cent 
higher. The results of the following year show the water require- 
ment of pasture plants to be over 90 per cent higher for the period 
June 4 to June 28 than for the period April 6 to June 4. Similar 
results were obtained with the grassland pots. 
BRIGGS AND SHANTZ'S EXPERIMENTS. 
The writers in their work at Akron, Colo., have found that the 
water requirement of alfalfa (Table L) was the lowest for the period 
from September 18 to October 22. From May 13 to July 19 it was 
94 per cent higher, and from July 19 to September 18, 160 per cent 
higher. With sweet clover the water requirement for the period 
from July 19 to September 21 was 17 per cent higher than for the 
period from May 13 to July 19. 
Table L. 
-Effect of the period of growth on the water requirement of crops, according to 
Briggs and Shantz (1913, p. 31.) 
Crop. 
Period of growth. 
Water 
require- 
ment. 
Crop. 
Period of growth. 
Water 
require- 
ment. 
Alfalfa 
(May 13 to July 19 
{July 19 to Sept. 18 
[Sept. 18 to Oct. 22 
1,008±26 
1,354±22 
520±9 
Sweet clover 
/May 13 to July 19 
\July 19 to Sept. 21 
675 ±5 
793 ±12 
A comparison of the writers' measurements of the water require- 
ment of wheat and sorghum grown in northeastern Colorado and in 
the Panhandle of Texas during the seasons of 1910 and 1911 is given 
in Table LI. The results show a higher water requirement for the 
crops grown in Texas, but the difference is relatively much greater 
for wheat than for sorghum, indicating that at least one of the crops 
is better adapted to one region than to the other. 
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