Mar. 1 , 1925 
Toxicity Studies with Dicyanodiamide on Plants 
421 
Table I. —Green weights of wheat from pots receiving various quantities of dicyano¬ 
diamide in the presence of a constant nitrate supply 
Norfolk sandy loam 
Chester loam 
Treatment a 
Fertilizer ratio 
NH 3 -P 2 O 5 -K 2 O | 
Green 
Aver- 
Increase 
or de- 
Green 
Aver- 
Increase 
or de- 
; 
weight 
age 
crease 
over 
weight 
age 
crease 
over 
check 
check 
Grams 
Grams 
No fertilizer 
0 - 0-0 
/ 8 . 4 
\ 8.0 
]• 8.2 
/ 12 .7 
\ 12.6 
} 12.7 
9.2 
16. 3 
9.0 
15.8 
No nitrogen _ . _ . 
0-8-4 
9.3 
8.0 
■ 8.9 
14.4 
17.9 
16.7 
9.2 
22.1 
8.5 
13.9 
18.2 
22.4 
Sodium nitrate 40..... 
4-8-4 
17.8 
18.9 
■ 19.2 
10.3 
21.4 
23.0 
■ 22.8 
6.1 
21.7 
24.2 
Dicyanodiamide 40 _ 
4-8-4 
j 6.8 
\ 7.9 
} 7 - 4 
-1.5 
f 14.9 
\ 14.3 
} 14.6 
- 2.1 
Sodium nitrate 40, dicyanodiamide 
5_____ 
| 4.5-8-4 
/ 18.8 
\ 18.9 
} 18.9 
10.0 
/ 22.8 
\ 21.5 
| 22.2 
5.5 
Sodium nitrate 40, dicyanodiamide 
10 . ___ 
| 5-8-4 
/ 18.4 
l 19.4 
} 18.9 
10.0 
/ 21.2 
\ 22.8 
} 22.0 
5.3 
Sodium nitrate 40, dicyanodiamide 
20 _ 
| 6-8-4 
/ 20.4 
\ 18.0 
} 19.2 
10.3 
/ 21.5 
\ 18.4 
| 20.0 
3.3 
Sodium nitrate 40, dicyanodiamide 
40___ 
} 8-8-4 
J 17.6 
\ 19.0 
} 18.3 
9.4 
/ 20.6 
\ 20.4 
j 20.5 
3.8 
r « In this table and those which follow the figures refer to pounds of nitrogen per acre expressed as NHj 
(2,000,000 pounds of soil). 
Table II.— Green weights of wheat from pots receiving various quantities of sodium 
nitrate in the presence of dicyanodiamide 
Treatment 
Fertilizer ratio 
NH 3 -P 2 O 5 -K 2 O 
No fertilizer.. 
No nitrogen_ 
Sodium nitrate 40. 
0 - 0-0 
0-8-4 
4-8-4 
Dicyanodiamide 40_ 
Dicyanodiamide 40, sodium nitrate 
Dicyanodiamide 40, sodium nitrate 
10 .___.... 
Dicyanodiamide 40, sodium nitrate 
20 .... 
Dicyanodiamide 40, sodium nitrate 
40.---- 
4- 8-4 
4.5-8-4 
5- 8-4 
6- 8-4 
8-8-4 
Norfolk sandy loam 
Chester loam 
Increase 
Increase 
Green 
Aver¬ 
or de¬ 
Green 
Aver¬ 
or de¬ 
weight 
age 
crease 
over 
weight 
age 
crease 
over 
check 
check 
Grams 
8.2 
Grams 
12.7 
8.9 
16. 7 
19.2 
10.3 
22.8 
6.1 
/ 6.8 
l 7.9 
} 7 - 4 
-1.5 
/ 14.9 
\ 14.3 
} 14.6 
- 2.1 
/ 10.2 ! 
\ 8.9 
} 9.6 
. 7 
/ 16.0 
\ 15.7 
} 15.9 
-.8 
/ 9.5 ! 
\ 10.9 i 
| 10.2 
1.3 
/ 18.9 
\ 19.1 
} 19.0 
2.3 
/ 11.6 
\ 13.6 
}• 12.6 
3.7 
/ 18.7 1 
l 18.7 
} 18.7 
2.0 
/ 17.6 
\ 19.0 
} 18.3 
9.4 
/ 20.6 
l 20.4 
| 20.5 
3.8 
B. Dicyanodiamide Constant; Sodium 
Nitrate Variable 
The green weights of wheat from 
pots receiving dicyanodiamide at a 
rate equivalent to 40 pounds of 
ammonia per acre with 0 to 40 pounds 
of sodium nitrate are given in Table II 
and in Figure 1. The data show that 
in the presence of sodium nitrate 
dicyanodiamide continues to exert an 
injurious, although not very noticeable, 
effect on the plants. Considering the 
pots receiving dicyanodiamide alone 
