EFFECT OF SOIL FACTORS OX WATER REQUIREMENT. 
53 
MONTGOMERY AND KIESSELBACH S EXPERIMENTS. 
Montgomery and Kiesselbach (1912) measured the water require- 
ments of corn grown in three types of soil, which they characterized 
as infertile, intermediate, and fertile. Each soil was used in its orig- 
inal condition and also with the addition of manure. Twenty-three 
cans were used in all, lour being used for each treatment, with a single 
exception. The cans were 16 inches in diameter and 36 inches high. 
A single corn plant was grown in each can. The potometers were 
covered, as in their earlier experiments. Modeling clay was used to 
make a tight joint between the stalk of the corn and the oilcloth cover. 
A summary of the experiments is given in Table XLI. 
The marked reduction in water requirement with the increase in 
soil fertility is definitely indicated. Another striking fact is the uni- 
formity in the water requirement of corn obtained in all three soil 
types when manure was used. The ratios obtained in the three 
experiments in which manure was used differ by less than the prob- 
able error, either when based upon total dry matter or upon the dry 
weight of the ears. 1 
Table XLI. — Water requirement of corn as influenced by soil fertility, according to 
Montgomery and Kiesselbach (1912, pp. 10-11). 
Average dry weight 
Water requirement based on- 
Soil. 
per plant. 
Total dry matter, i Dry ears. 
No 
manure. 
Manure. 
No 
manure. 
Manure. 
No 
manure. 
Manure. 
Infertile 
Grams. 
113 
184 
270 
Grams. 
376 
414 
473 
550±16 
479±11 
392 ± 6 
350±8 
341 ±4 
347±6 
2,136±436 
1,160± 59 
799 ± 39 
692 ±45 
Intermediate 
679 ±36 
Fertile 
682 ±18 
PFEIFFER, BLANCK, AND FLUGEL S EXPERIMENTS. 
Pfeiffer, Blanck, and Fliigel (1912), experimenting with the effects 
of different amounts of nitrogen on the water requirement of plants, 
found that for the particular soil used the addition of nitrogen did not 
measurably lower the water requirement. The experiment is dis- 
cussed in connection with the effect of soil-moisture content on the 
water requirement and the results are shown in Table XIII (p. 24). 
CONCLUSIONS. 
Almost without exception the experiments herein cited show a 
reduction in the water requirement accompanying the use of ferti- 
lizers. In highly productive soils this reduction amounts to only a 
1 The writers are indebted to Prof. Kiesselbach for an advance proof of this paper, and also for detailed 
information concerning earlier experiments, which has made the calculation of probable errors possible. 
285 
