EFFECT OF SOIL FACTORS OX WATER REQUIREMENT. 
21 
Xo differences in the water requirement greater than the probable 
error occur in the case of the plants grown at other degrees of satura- 
tion. 
Table XI. — Influence of soil-moisture content on the water requirement of corn, accord- 
ing to Kiesselbach {1910. p. 125). 
Water requirement 
Average 
based on dry weight. 
Saturation. 
dry weight, 
without 
roots. 
Excluding 
Including 
roots. 
roots. 
Per cent. 
Grams. 
9S 
91.1 
270 
242±S 
80 
93.1 
272 
239 ±9 
60 
100. G 
256 
227 ±10 
40 
92.9 
270 
233±7 
20 
83.2 
239 
201±5 
KIESSELBACH AND MONTGOMERY S EXPERIMENTS. 
Kiesselbach and Montgomery (1911) extended Kiesselbach's 
investigation with corn, using large pots in which the plants were 
brought to maturity. Single plants 
were grown in galvanized-iron pots 16 
inches in diameter and 3 feet deep. 
The construction of their potometer 
is shown in figure 2 . "Water was added 
through a perforated f -inch brass pipe 
15 feet long bent in the form of a heli- 
cal coil. Evaporation from the soil 
was minimized .by a layer of gravel 3 
inches deep . R ain was excluded with 
the aid of a galvanized-iron lid having 
a 4-inch opening in the center for the 
plant, the opening being covered with 
oilcloth closely fastened about the 
cornstalk. The potometers were lo- 
cated in a cornfield and were appar- 
ently sunk in trenches so that the tops 
of the pots were level with the surface 
of the surrounding field. The potom- 
eters were mounted on small, indi- 
vidual trucks and were run on 
tracks to a platform scale which was mounted on a cross track. 
Five different degrees of soil saturation were maintained, namely, 
100, 80, 60, 45, and 35 per cent. Saturation was regarded as the 
amount of water retained by the soil when drainage had ceased after 
pouring water on the soil surface. One hundred pounds of water 
285 
/S" 
Fig. 2 
Pot employed by Kiesselbach and 
Montgomery (1911) in measuring the water 
requirement of corn. 
