4 
Journal of Agricultural Research 
Vol. XXVI, No. f 
However, treatment with calcium carbonate checked the loss of nitrites 
so that appreciable amounts were present after thirty days. 
Soils No. 11079 and 11080 are strongly acid, and, consequently, the 
former lost most of the nitrite, and the latter all of the nitrite, in 48 
hours. These soils provide conclusive evidence that the nitrites are 
not changed to some other form and retained, since immediately after 
the addition of sodium nitrite, fumes of escaping nitrous acid could 
easily be detected by their characteristic odor. The high acidity of 
these soils also furnishes equally definite evidence that the loss of nitrites 
is a natural consequence, owing to the reaction between the sodium 
nitrite and the acid soil. Considered from the standpoint of a chemical 
reaction the results are in accord with theoretical conclusions. When 
sodium nitrite is added to an acid soil it reacts with the soil minerals, 
causing an excess of acidity or hydrogenions in the soil solution. The 
reaction may be represented by the following equation: 
NaN 0 2 + HR - NaR + HN 0 2 
Subsequently the nitrous acid, which is very unstable, and exists only 
under abnormal conditions, rapidly escapes after decomposition, de¬ 
pending upon the degree of acidity formed. 
In order to prove definitely whether the nitrites were actually lost 
from the soil by decomposition, an endeavor was made to collect the 
escaping nitrous acid fumes in standard potassium permanganate. An 
absorption tower and two bottles containing o. 1 N potassium permanga¬ 
nate were connected in series with a flask containing the soil. Washed 
air was then drawn through the apparatus. The excess potassium per¬ 
manganate not reduced by the nitrous acid was then titrated with 
sodium thiosulphate after the addition of potassium iodid, and the 
amount of nitrous acid estimated. In this manner all but a small 
amount of the escaping nitrous acid was recovered. This result sub¬ 
stantiates the conclusion inferred from the results given in the table that 
the nitrites were not oxidized to nitrates, but were lost by decomposition. 
Attention is called to the effects of calcium carbonate and calcium 
hydroxid in retarding the decomposition of nitrites. In the case of 
soil No. 11080, although both calcium carbonate and calcium hydroxid 
had been added in sufficient amounts to neutralize the acidity of the 
soil, it will be observed that most of the nitrite had disappeared in 48 
hours and only a trace was detected after six days. After the disap¬ 
pearance of nitrites these same pots were again treated with similar 
amounts of calcium carbonate and calcium hydroxid, or a total of 4.0 
grams and 3.0 grams, respectively, for each pot. After standing 24 
hours 0.4 gram of sodium nitrite was again added. To the pot receiving 
calcium carbonate 0.5 gram of monocalcium phosphate was also added, 
to observe whether the phosphate would prevent decomposition of the 
nitrites. Determinations made after 48 hours and after six days indi¬ 
cate that the acid condition had been neutralized, since the loss of 
nitrites was comparatively low. Monocalcium phosphate did not pre¬ 
vent loss of nitrites, and probably was converted into the tricalcium 
phosphate form in the pot where calcium carbonate was added. 
In the second series particular care was taken to select soil types that 
were neutral and alkaline. A brief description of the soils is as follows: 
Soil No. 9673 is classified as a gravelly clay loam, and is practically 
neutral, as indicated by the Veitch (7) method. It contains 3.4 per cent 
