104 
Journal of Agricultural Research 
Vol. II, No. a 
0 ./<T 
0 ./+ 
O.iZ 
a/o 
course, recognized that records of fertilizer practice in California are 
meager and unsatisfactory. Somewhat extensive greenhouse experi¬ 
ments have been carried on in Washington, and although laboratory 
results can not be directly translated into field conditions, the results 
again indicate that nitrate 
nitrogen in excess produces 
the typical symptoms of 
malnutrition. In the ex¬ 
periments reported in detail 
in Tables I, II, and III both 
greenhouse soil and virgin 
California soil from typical 
orange-growing areas were 
used. Moderate quantities 
of nitrate gave no apparent 
result, but it has been noted 
in earlier publications (Moore 
and Kellerman, 1905) that 
toxic limits established in 
the laboratory may be ex¬ 
pected to be much higher 
than will be found to exist under a natural and favorable environment. 
If the hypothesis of overstimulation in southern California is accepted, a 
wide variation between the low inhibiting or toxic limits in the field and 
comparatively high toxic limits found in the greenhouse in Washington 
is therefore to be expected. 
0.06 
GO? 
1 
C77I 
. .. ...1 
1 
1 
! 
1 
J 
! 
1 
* 
1 1 
1 
(1 
1 
; 
B ! 
■ H ! 
- 
■i 
1 
ji 
■ J 
j |l 
1 1 
i 
11 
II 
1 
JL 
Fig. 4— Diagram showing quantities of salts found in crust 
samples of soil from the same areas illustrated in figures i, 
3, and 3. 
Table I .-—Effect of certain salts and combinations of salts on grapefruit seedlings grow¬ 
ing in greenhouse soil at the Department of Agriculture , Washington , D. C. a 
Lab¬ 
oratory 
No. 
Soil treatment. 
Condition of trees after 74 
days. 
Condition of trees after 144 
days. 
770 
771 
772 
773 
774 
775 
776 
Check.. 
Normal.. 
Normal. 
.do . 
.do. 
Do. 
CaCO? (5 per centl. 
.do. 
Slight leaf burning (?). 
. .. do . . 
.do... 
Normal. 
N as KNO3 (0.04 per cent). 
.do . 
Leaves shed. 
Leaves burning. 
Leaves shed. 
Leaves burning. 
CaCC>3 (1 per cent) + N asKNCb 
Leaves shed. 
New leaves; chlorotic. 
777 
778 
779 
(0.04 per cent), 
do . 
.do. 
Do. 
Cl as NaCl (a.e >4 per cent). 
Normal. 
Leaves burning. 
.do. 
Do. 
a Grapefruit seedlings 2 years and 4 months old, about 24 inches in height, were transplanted into 6-inch 
pots of soil mixture consisting of equal parts of sand and sod composted in rather stiff clay soil. 
