34 
WATER REQUIREMENT OF PLANTS. 
DEHERAIN S EXPERIMENTS. 
Deherain (1892) reported experiments on the effect of different 
fertilizers upon the water requirement of ray-grass and clover (Table 
XXIV). To determine the water consumed, the amount of water 
which drained through the soil was deducted from the amount which 
fell upon the soil as rain. No correction was made for differences 
in the water content of the soil at the time of planting and at harvest, 
or for the direct loss by evaporation. The results show a lower water 
requirement in a manured soil than in a poor soil not manured. 
Table XXIV. — Effect of different fertilizers on the water requirement of ray-grass and 
clover, according to Deherain (1892, pp. 471-473). 
Ray-grass. 
Clover. 
Soil and treatment. 1 
Dry Water re- 
matter, quirement. 
Dry 
matter. 
Water re- 
quirement. 
Grams. 
45 
39 
102 
04 
05 
630 
682 
2 266 
435 
449 
Grams. 
89 
05 
72 
99 
95 
322 
454 
398 
Poor soil and manure water in 1890; K, N, and P ferti- 
lizer in 1891 
255 
Poor soil and manure water in 1890 and 1891; K, N, and 
P in 1891 
272 
1 The water loss included evaporation. Each pot contained about 60 kilograms of soil, and the water 
content was assumed to be the same at the time of harvest as at the time of planting. The amount of K, N, 
and P was practically the same in the last three pots; the first contained N in the form of nitrate of soda 
and ammonium sulphate, while the last two contained organic nitrogen. The experiment continued from 
Apr. 7 to Sept. 4, 1891 (?). 
2 Deherain erroneously gives 233. 
KING S EXPERIMENTS. 
King (1894) investigated the effect of fertilizers on the water 
requirement of potatoes and corn, using large open pots. In the 
work with the potato, 6 galvanized-iron cylinders, 18 inches in 
diameter and 42 inches deep, were used. These stood above ground 
and were protected on the south side by a screen of boards. Each 
pot was watered through a 3-inch draintile set vertically in the pot 
against one side. The level of standing water in the pots was not 
allowed to rise over 6 inches from the bottom. The pots were pro- 
tected at night and during rainy weather by a tent of heavy duck. 
The fertilized pots each received 5.3 grams of potassium nitrate 
before planting and the same amount the preceding year, during 
which time the pots were kept fallow. The results, which are given 
in detail in Table XXV, indicate that the use of potassium nitrate 
does not affect the water requirement of potatoes. In the case of 
corn the use of manure apparently reduced the water requirement 
markedly, but the result is affected with a large probable error. 
285 
