44 
WATER REQUIREMENT OF PLANTS. 
VON SEELHORST AND BUNGER S EXPERIMENTS. 
Von Seelhorst and Biinger (1907) measured the water requirement 
of summer wheat grown in pots containing 12 kilograms of soil. 
Different fertilizers were used. The results are given in Table XXXII. 
The experiments were conducted in open pots. It is not clear from 
Von Seelhorst and Biinger's description of their experiments whether 
the data as given in the table have been corrected for evaporation 
from the soil. The fertilizer scheme followed is stated to be the same 
as that used in one of the experiment fields at Gottingen, but details 
are not given. Both the increased yield and lower water requirement 
accompanying the use of nitrogen indicate that nitrogen is the defi- 
cient food element in the soil used in this experiment. The higher 
mean water requirement obtained with five plants in a pot as com- 
pared with a single plant also indicates a deficient supply of some 
food element. 
Table XXXII.— Effect of different fertilizers on the water requirement of summer wheat, 1 
according to Von Seelhorst and Biinger (1907, p. 247). 
Lew water content. 
High water content. 
Fertilizer. 
One plant. 
Five plants. 
One plant. 
Five plants. 
Mean 
water 
require- 
ment. 
Dry 
matter. 
Water 
require- 
ment. 
Dry 
matter. 
Water 
require- 
ment. 
Dry 
matter. 
Water 
require- 
ment. 
Dry 
matter. 
Water 
require- 
ment. 
K 
10.6 
24.4 
9.3 
27.7 
10.5 
28.7 
10.8 
21.7 
26.5 
229 
217 
197 
222 
217 
217 
197 
211 
227 
13.1 
31.9 
12.9 
36.0 
12.5 
41.2 
13.9 
39.4 
40.3 
269 
255 
240 
233 
272 
225 
261 
228 
236 
14.1 
49.6 
12.3 
467 
227 
405 
15.3 
72.5 
15.9 
74.1 
12.5 
68.5 
16.6 
76.2 
82.6 
N 
255 
368 
257 
239 
P 
303 
KNP 
Check 
13.2 
56.2 
12.5 
46.2 
52.6 
309 
259 
344 
237 
240 
KN 
278 
362 
267 
245 
245 
KP 
291 
PN 
236 
CaKNP 
237 
18.9 
215 
26.7 
247 
48.2 
Mean water re- 
quirement for 
all but K. 
KNP, and 
211 
241 
285 
296 
The pots contained 12 kilograms of loam soil. 
ohlmer's experiments. 
Ohlmer (1908) measured the effect of different fertilizers on the 
water requirement of squarehead wheat. Open pots were used and 
no correction was made for evaporation from the soil. The results 
(Table XXXIII) show a reduction in the water requirement when 
nitrogen is added. The addition of phosphorus, potash, and calcium 
slightly increased the water requirement. 
285 
