20 
WATER REQUIREMENT OF PLANTS. 
LEATHERS EXPERIMENTS. 
Leather (1910) has also investigated the influence of the soil- 
moisture content on the water requirement of wheat and corn at 
Pus a, India. His determinations are given in detail in Table XXXIX 
(p. 51), each determination being based upon a single open jar. 
From these measurements the writers have computed the mean water 
requirement obtained for each soil-moisture content when different 
fertilizers were used. These means are to be found in the last columns 
of the tables referred to and are, of course, comparable only in so far 
as they apply to jars of the same size and to the same series of ferti- 
lizers. A summary of the observations for each soil-moisture content, 
obtained by averaging the mean values found with pots of different 
capacity, is also given in Table X. The results are seen to be in 
agreement within the limits of experimental error. In other words, 
an increase in the moisture content of Pusa soil from 10 to 20 per cent 
of the saturation content did not affect the water requirement by an 
amount exceeding the experimental error. 
Table X. — Effect of soil-moisture content on the water requirement of ivheat and corn at 
Pusa, India, according to Leather (1910, p. 133). 
Year. 
Total pots 
used with 
each water 
content. 
Water requirement with— 
Crop. 
10 per cent 
water. 
15 per cent 
water. 
20 per cent 
water. 
Wheat 
/ 1906-7 
\ 1907-8 
1907 
8 
6 
9 
747 
562 
414 
707 
737 
404 
436 
KIESSELBACH S EXPERIMENTS. 
Kiesselbach (1910) has measured the effect of soil-moisture content 
on the water requirement of corn at Lincoln, Nebr., using covered 
4-gallon glazed stone jars, containing 14.5 kilograms of dry loam. 
Water was added through a tube to a reservoir formed by inverting 
a 4-inch flower pot in the bottom of the jar. Surface evaporation was 
prevented by the use of gravel and paraffined parchment paper. 
The plants were grown in a cornfield, one plant to a jar. An oilcloth 
cover was used on each jar to keep out rain, and a temporary canvas 
cover was put on during rainstorms. The jars were weighed once 
in 48 hours and sufficient water added each time to restore the original 
weight. The variation in degree of saturation during this period 
ranged from 5 to 10 per cent. The plants were harvested shortly 
after the silking stage. The results are shown in Table XL The 
plant grown in soil 20 per cent saturated wilted when the conditions 
gave rise to high transpiration. This may be associated with the 
slightly lower water requirement recorded in the case of these plants. 
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