68 
WATER REQUIREMENT OF PLANTS. 
water independent of its leaf area. Further experimentation, using 
strains of other plants with high and low leaf areas, is desirable in this 
connection. 
EFFECT OF FREQUENT CUTTING ON THE WATER REQUIREMENT. 
von seelhorst's experiments. 
Von Seelhorst (1910) conducted an experiment to determine the 
water requirement of grassland and pasture. The pots used by Von 
Seelhorst (1902, p. 276) had a surface 1 square meter in area, a 
depth of 1.3 meters, and were mounted upon trucks in a trench run- 
ning east and west, which was provided with cement walls and floor 
Fig. 4. 
Apparatus used by Von Seelhorst (1902) in his later measurements of the water requirement of 
plants. 
(fig. 4). The bottom of the pot (a) was so constructed as to permit 
free drainage. The scales (b) for weighing the trucks were built in 
as a part of the trench (d). The rainfall was determined from the 
rain-gauge measurements or directly by weighing, and the drainage 
water was also collected. No correction was made for evaporation. 
The pots which represented pasture were cropped more often than 
those which represented grassland. This was apparently the only 
difference in treatment. Ordinary grassland and pasture grasses were 
grown. The results of two years' work are shown in Table LIX, 
from which it will be seen that the water requirement was higher 
under pasture-land conditions than under grassland conditions. From 
these results, one would conclude that the frequent and continued 
cropping as the result of pasturing increases the water requirement 
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