43 ^ 
Journal of Agricultural Research 
Vol. VII, No. 10 
solution of the soil was made up as usual. To an aliquot portion, io c. c. 
of a i per cent solution of ammonium sulphate was added, then evap¬ 
orated on the water bath, and the determination completed as usual 
with the phenol-disulphonic-acid method. During the evaporation the 
ammonium sulphate brings about complete decomposition of the nitrite 
through the formation of ammonium nitrite, which decomposes at the 
temperature employed. 1 The nitrite was determined by the Griess- 
Ilosvay method. 
The following data (Table VII) will show the wide range of results 
obtained by the use of different methods: 
Tabu® VII .—Effects of nitrite on the determination of nitrate (in parts per million) 
Nitrite 
nitrogen. 
Nitrate 
nitrogen by 
modified 
coloro- 
metric 
method. 
Nitrate 
nitrogen by 
the usual 
coloro- 
metric 
method. 
Nitrate 
nitrogen by 
aluminum 
reduction 
method. 
Soil plus i per cent of dried blood incu¬ 
bated for 46 days. 
275 
22 
30 
283 
The above data show that nitrite becomes reduced to ammonia under 
the conditions employed in the aluminum reduction method. It is 
reasonable to infer, therefore, that unless allowance be made for the 
nitrite present the results obtained by the reduction method from incu¬ 
bations with high concentrations of nitrogenous materials will represent 
the total nitrite and nitrate present rather than the nitrate only (22). 
It has been found that with the use of 1 per cent of dried blood nitrites 
may accumulate in large amounts in soils of various types and that the 
nitrite may persist without undergoing further oxidation, at least for 
a period of 105 days, as shown in Table VIII. 
Table VIII .—Accumulation of nitrite as affected by concentration (in parts per million) 
Original 
soil. 
After 
28 days. 
After 
42 days. 
After 
56 days. 
After 
71 days. 
After 
ios days. 
Soil. 
Ni¬ 
trite 
nitro¬ 
gen. 
Ni¬ 
trate 
nitro¬ 
gen. 
Ni¬ 
trite 
nitro¬ 
gen. 
Ni¬ 
trate 
nitro¬ 
gen. 
Ni¬ 
trite 
nitro¬ 
gen. 
Ni¬ 
trate 
nitro¬ 
gen. 
Ni¬ 
trite 
nitro¬ 
gen. 
Ni¬ 
trate 
nitro¬ 
gen. 
Ni¬ 
trite 
nitro¬ 
gen. 
Ni¬ 
trate 
nitro¬ 
gen. 
Ni¬ 
trite 
nitro¬ 
gen. 
Ni¬ 
trate 
nitro¬ 
gen. 
Control plot untreated. 
0 
1.4 
0 
12.0 
0 
11.2 
0 
12 
0 
is 
0 
18 
Control plot plus 0.0625 per 
cent of dried blood. 
0 
1.4 
Trace. 
60.0 
0 
70.0' 
0 
70 
0 
67 
0 
68 
Control plot plus 1 per 
cent of dried blood. 
0 
1.4 
20 
19*5 
87*5 
26.0 
is© 
19 
iso 
24 
265 
29 
Manured plot untreated.... 
0 
3* 2 
0 
14.0 
0 
17.0 
0 
17 
0 
26 
0 
25 
Manured plot plus 0.0625 
per cent of dried blood,.. 
0 
3*2 
Trace. 
So-o 
0 
60.0 
0 
72 
0 
74 
0 
70 
Manured plot plus 1 per 
cent of dried blood. 
0 
3*2 
107 
160.0 
56*0 
272.0 
75 
390 
0 
46s 
0 
416 
1 This procedure was suggested by the method formerly employed for the determination of nitrate in 
the presence of nitrite by Frankland (6). 
