56 
WATER REQUIREMENT OP PLANTS. 
Table XLIV. — Water requirement of oat plants grown in culture solutions of different 
concentrations, according to Heinrich (1894, p. 173). 
Concentration of culture solution. 
Dry 
matter. 
Grain. 
Water 
tran- 
spired. 
Water requirement 
based on— 
Grain. 
Dry 
matter. 
3 grams per liter.. 
1 gram per liter... 
0.5 gram per liter. 
0.25 gram per liter 
0.1 gram per liter. 
Grams. 
134.3 
74.4 
41.5 
27.8 
17.6 
Grams. 
5.42 
2.71 
.59 
1.07 
1.41 
Kilos. 
69.2 
40.9 
28.4 
19.1 
11.3 
12.800 
15, 100 
48,200 
17,900 
8,020 
515 
550 
688 
642 
CONCLUSION. 
The water requirement of plants grown in water cultures is increased 
if the solution is lacking in a sufficient amount of plant food. 
EFFECT OF A PREVIOUS CROP ON THE WATER REQUIREMENT. 
von seelhorst's experiments. 
The effect of a previous crop on the water requirement of rye is 
shown in a series of determinations made by Von Seelhorst (1910a). 
These determinations were made in the large pots shown in figure 4 
(p. 68). The results of the determinations are given in Table XLV. 
The experiments were conducted with two series of pots, one series 
having received a light application of manure each spring from 1904 
to 1907 and the other a heavy application of manure each fall during 
the same period. A crop was grown in each pot from 1905 to 1908. 
In the fall of 1908 all pots were planted to rye and the crop harvested 
in 1909. 
Table XLV. 
-Effect of a previous crop on the water requirement of rye, according to Von 
Seelhorst (1910a, p. 91). 1 
Crops, 1905 to 
1908. 
Rye, 1908-9. 
Application of manure, 1904 to 1907. 
Number 
of pots. 
Yield. 
Water re- 
quirement. 
(Potatoes 
JRye 
3 
2 
1 
Grams. 
426 
393 
526 
743 ±23 
759 ±4 
[Barley 
589 
697 
fPotatoes 
jRye 
3 
2 
1 
421 
374 
482 
748 ±18 
801 ±33 
IBarley 
666 
738 
Rye 
1 
339 
900 
i The water requirement includes evaporation. The soil was sandy. The results were compiled from 
Von Seelhorst's data. In the late summer and fall of 1906 each pot, with the exception of the unmanured 
set, produced a crop of lupine. 
285 
