430 
Journal of Agricultural Research 
Vol. VII, No. 10 
However, nitrite may accumulate to a considerable extent under poorly 
aerated conditions, especially when artificial applications of nitrate fer¬ 
tilizers are made, but under such conditions it is highly probable that the 
nitrite is formed in part at least through the reduction of nitrates rather 
than from the incomplete oxidation of ammonia. The writer (12) has 
shown, for example, that the application of sodium nitrate to rice soils 
immediately preceding or during the time of submergence may result in 
an accumulation of considerable amounts of nitrite. The addition of 
large amounts of carbohydrates may also bring about a similar reduction 
of nitrates, even under aerobic conditions. In general, it may be said 
that the accumulation of notable amounts of nitrite in soils is an indica¬ 
tion of the existence of unfavorable soil conditions. 
Notable amounts of nitrite have previously been found in laboratory 
incubation experiments on nitrification. In experiments with the use of 
asparagin Withers (35) found considerable amounts of nitrite in certain 
soils in North Carolina, while only slight nitrate formation took place. 
On the other hand, ammonium sulphate was oxidized to nitrate without 
the accumulation of more than a trace of nitrite. In sterilized portions 
of this soil, which were later exposed to reinoculation, notable amounts 
of nitrite were formed within four weeks’ time from both asparagin and 
ammonium sulphate, but practically no nitrate was formed from either. 
The amounts of nitrogenous materials used in these experiments were 
not stated. 
Sackett (28) also found considerable amounts of nitrite in laboratory 
experiments. He used 100 mgm. of actual nitrogen in the form of ammo¬ 
nium sulphate, ammonium chlorid, ammonium carbonate, and dried 
blood per 100 gm. of soil, which corresponds, in the case of ammonium 
sulphate, to a concentration of about 0.5 per cent, and in that of dried 
blood approximately to 0.75 per cent. The incubation period was six 
weeks. It is notable that in certain soils he found that nitrite formation 
took place much more rapidly than nitrate formation, and in other soils 
there was evidence of nitrite formation through the reduction of nitrate. 
In the control portions to which no nitrogenous materials were added 
the concentrations of nitrite did not amount to more than 1 to 2 p. p. m. 
It is probable that the results obtained by Sackett would have been 
greatly different had he employed a lower concentration of the nitroge¬ 
nous materials. 
The writer (13) has also previously found considerable amounts of 
nitrite in laboratory experiments with the use of excessive amounts of 
magnesium carbonate. In these experiments a concentration of 2 per 
cent of dried blood was employed with the light, sandy soil from Anaheim, 
Cal. In discussing this point it was tentatively suggested that the 
nitrite found arose from the reduction of nitrate, and that the magne¬ 
sium carbonate was more toxic to the nitrifying bacteria than to the 
denitrifiers. In the light of evidence obtained more recently it seems 
