EFFECT OF SOIL FACTORS OX WATER REQUIREMENT. 
33 
Table XXII. — Effect of fertilizers on the water requirement of wheat, according to Maril- 
Davy {1875, pp. 305-309 i. 1 
Treatment. 
Dn- 
grain. 
Water 
require- 
ment of 
gram. 
Grams. 
2.32 
1,546 
5.40 
5.52 
4.9S 
968 
1,181 
1.393 
1.006 
4.20 
7.50 
4. IS 
4. 65 
9.72 
1.046 
988 
1,165 
9S1 
Not fertilized 
1.5 grams each per pot— 
CaHP04, KXOg, and XaCl 
KX0 3 , (XH ( )i P0 4 , and XaCl 
XajHP0 4 , KjCOi, and CaSO< 
KX0 3 , XaCl, and CaSO< 
Soil watered with, solution containing 94 milligrams (XH<} 3 PO<, 200 milligrams 
XH4XO3, 105 milligrams KXO3, and 16 milligrams XaCl per liter ' 
As above plus 10 per cent leaf mold 
10 per cent leaf mold 
20 per cent leaf mold 
40 per cent leaf mold 
1 Each treatment was repeated on six different soils. 1 See Table XIV, p. 25.) The treatment given for 
this experiment by Marie-Davy (1S74) does not conform exactly to the record here given. It is not clear 
which is correct. 
HELLRIEGEL S EXPERIMENTS. 
Heilriegel (1883) carried on several experiments to determine the 
effect of different amounts of fertilizer on the water requirement, 
using open pots containing 4 kilograms of quartz sand. His results 
(Table XXIII) show a great decrease in the water requirement as 
the amount of fertilizer is increased. The water requirement was 
doubled by the absence of potassium and trebled by the absence of 
nitrogen. A correction for direct evaporation from the soil had to 
be made, which introduced an element oi uncertainty into the results. 
An abnormally high water requirement would, however, be expected 
in the case of a plant growing in a soil which was deficient in any 
essential element of plant food. Its growth would be arrested, but 
transpiration would still go on. 
Table XXIII. — Effect of calcium nitrate and potash on the water requirement of barley, 
according to Heilriegel \1883, pp. 629-631 >. 
Period. 
Determination. 
Milligram equivalents of calcium nitrate. 
20 16 12 10 
Apr. 30 to Aug. 6, 1868, 98 
davs 
May'3to July 24, 1869,82 
days 
/Water requirement 33S 
\Drv matter grams.. 16.5| 
/Water requirement 292 302 
\Drv matter grams.. 25.5 23.0 
13.5 12.2 
345 347 
IS. 3 13.9 
42o 481 
9.5 'o.^, 
399 
8.5 
0.7 
:796±53 
: 1 . 1 _ 
Period. 
Determination. 
Milligram equivalents of potash. 3 
3.0 
2.2 1.6 1.2 
0.8 
0.4 

Apr. 30 ,0 Aug. 6, im, 9 8 days. . . . §™l^ m %ni\ \ 
330 
20.8 
_ 390 453 
IS. 4 17.3 ! 15.7 
422 
15.4 
525 
10.8 
615 
6.4 
1 Soil used: Four kilograms of quartz sand plus 2 KH2PO4, 1 KC1, and 1.6 MgSO< in milli gram equiva- 
lents. 
2 Mean of two measurements. 
J Soil used: Four kilograms of quartz sand plus 1.6 Ca (N0 3 )j and 1.6 MgS(J« in milligram equivalents. 
97991°— Bui. 28.5—13 3 
