EFFECT OF CLIMATIC FACTORS ON WATER REQUIREMENT. 59 
Table XL VIII. — Effect of different atmospheric conditions on the water requirement of 
oats, according to Fittbogen. 
Position. 
Number 
of deter- 
minations. 
Dry 
matter. 
Grain. 
Water requirement 
based on— 
Grain. Dry matter. 
Inside of plant house 
Outside of plant bouse, on south side. 
Grams. 
13.7 
12.7 
Grams. 
7.01 
6.46 
777 = 10 
810 ±3 
398±6 
413 ±1 
Calculated from Fittbogen's data (1S74, p. 145). 
HELLRIEGEL S EXPERIMENTS. 
Hellriegel (1883) determined the effect of seasonal differences upon 
the water requirement by a series of measurements. The re- 
sults are given in Table XLIX. Red clover was used in this 
experiment, croppings being made at four different times during a 
period of two years and the water requirement of each crop deter- 
mined. It will be seen from this table that the water require- 
ment was much higher for the crops harvested in September and 
January than for the crops harvested in June and July, owing to 
variation in the climatic conditions with different periods of the year. 
Hellriegel also conducted a series of experiments which show the 
effect of different years on the water requirement. (Table LXYII, 
p. 75.) The water requirement of barley in 1868 was almost 40 
per cent higher than hi 1870. Similar results were obtained during 
different seasons with other crops. 
Table XLIX. — Effect of the period of growth on the water requirement of red clover, 
according to Hellriegel (1883, p. 6 
Pot used. 
Date of cropping 
July 17, 1872. 
Sept. 14, 1S72. Jan. 8,183 June S 
Height. 
No. 
Dry 
matter. 
Water 
require- 
ment. 
Dry 
matter. 
Water 
require- 
ment. 
Drv Water 
Drv Water 
Wer. -Hf 
15 centimeters 
Grams. 
12.8 
302 
311 
Grams. 
12.8 
8.4 
435 
071 
Grams. 
0.5 1.588 
Grams. 
292 
315 
15.0 
1.2 
1,045 
18.2 
337±22 
553±100 
1,017±25 
3S0±76 
346 
347 
26.2 
14.3 
349 
401 
Note 
ropped. 
23.6 
2.5 
703 
854 
69.8 
50.8 
111.5 
98.4 
168.2 
157.0 
264 
14.3 
652 
302 
375 ±22 
809±39 
283±16 
348 
349 
30.0 
21.0 
25.8 
21.2 
Note 
17.4 
10.2 
293 
417 
439 
546 
451 
256 
5.2 649 
5454-79 
285 
\fpan 
355 ±53 
493 ±46 
271+13 
350 
351 
20.2 
25.0 
52.5 
11.0 
357 
410 
ropped. 
577 
680 
563 
243 
263 
Mean 
384 ±23 
622 ±50 
2534-8 
285 
