EFFECT OF SOIL FACTORS ON WATER REQUIREMENT. 
31 
Leather adopted for his later experiments jars containing about 
50 kilograms of soil. Plants like maize and juar (jowar) were found 
to develop much better in these large jars than when grown in jars 
holding one-fourth as much soil. 
Table XX. — Effect of the amount of soil used on the water requirement of wheat and 
maize, according to Leather {1910). 
Crop. 
Year. 
Number 
of jars 
used. 
Amount of 
soil used 
per jar. 
Water re- 
quirement. 
Wheat 
1906-7 
1907-8 
1907 
12 
<i 
9 
Kilograms. 
1 15 
\ 22 
1 15 
\ 27 
15 
21 
31 
722 
454 
719 
590 
415 
441 
Do 
393 
CONCLUSIONS. 
Leather's data are conclusive in showing the influence of the soil 
mass on the water requirement. An insufficient soil mass increases 
the water requirement, probably as a result of an insufficient supply 
of plant food. 
EFFECT OF FERTILIZERS ON THE WATER REQUIREMENT. 
Soil Cultures. 
LA-WES S EXPERIMENTS. 
The earliest investigations regarding the effect of plant food on 
the water requirement were carried on with water cultures and will 
be considered in a subsequent section. Lawes (1850) appears to 
have been the first to use fertilizers in connection with soil cultures 
in investigating the water requirement. His results, which were 
obtained at the Kothamsted Station, England, are shown in Table 
XXL 
Table XXI. — Effect of fertilizers on the water requirement of different crop plants, 
according to Lawes (1850, p. 54)- 
Fertilizer and crop. 
Dry 
matter. 
Water 
trans- 
pired. 1 
Water 
requ ire- 
Mean water 
requirement. 
Wheat, 
barley, 
and 
clover. 
All 
plants. 
Unmanured: 
Wheat 
Barley 
Clover 
Beans 
Peas 
Mineral manure: 
Wheat 
Barley 
Clover 
Beans 
Ammoniacal and mineral manure: 
Wheat 
Barley 
Clover 
Grams. 
29.7 
30.2 
13.3 
34.8 
27.3 
28.6 
32.5 
15.2 
34.8 
29.6 
17.6 
'jo.;? 
6.0 
Kilograms. 
7.35 
7.78 
3.57 
7.27 
7.07 
6.35 
8.32 
3.48 
7.64 
6.24 
3.63 
5.52 
247 
258 
259 
222 
256 
229 
219 
211 
206 
272 
148 
258 
248 
227 
209 
285 
Data recalculated to metric units. 
