420 
Journal of Agricultural Research 
Vol. XXX, No. 5 
These figures show that dicyano- 
diamide at the high rate of 40 pounds 
of ammonia per acre is only slightly 
toxic to wheat under the conditions 
used. On the sandy Norfolk soil the 
decrease in weight of the plants 
amounted to approximately 17 per 
cent and on the Chester loam to 13 
per cent, as compared with the control. 
Where sodium nitrate was used together 
with different quantities of dicyano- 
diamide, the green weights were prac- 
toxic to wheat to a slight extent at 
the high rate used but can not be con¬ 
sidered as a marked direct poison. It 
did not greatly lessen the fertilizing 
value of sodium nitrate or greatly 
affect the growth of the plants. 
The observations made during 
growth of the wheat corresponded 
rather closely to the final green weights. 
Dicyanodiamide caused a slight tip¬ 
burning at all rates of application on 
the Norfolk sandy loam, the burning 
23 
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&A/.40 40 40 40 40 O 
O S /O 20 40 40 
40 40 40 40 40 O 
1 
23 
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Fig. 1.—Diagram showing the yields of wheat from pots receiving various amounts of dicyanodiamide 
and sodium nitrate 
tically as large with the dicyanodiamide 
as without in the case of the lighter 
soil. The dicyanodiamide did cause 
a slight drop at the highest rate, but 
this was almost within experimental 
error. On the Chester loam the re¬ 
sults were similar, except that both 
20 and 40 pounds of ammonia as 
dicyanodiamide used with sodium ni¬ 
trate caused slight decreases as com¬ 
pared with nitrate alone. These results 
seem to show that dicyanodiamide is 
being greatest when the plants were 
about 2 weeks old. There was a par¬ 
tial recovery later. At the rates of 
20 and 40 pounds of ammonia, many 
of the leaf tips were burned back 2 
to 3 inches. The rate of growth did 
not appear to be greatly affected, 
however. The burning effect was 
not lessened by application of sodium 
nitrate. On the Chester loam there 
was practically no burning at any 
time. 
