The Soil. 
45 
TABLE XX —NITRATES IN THE SOIL. 
Water-Soluble. Nitrogen. Nitric Acid. Potassic Nitrate. 
A—First two inches... .39,314 0 7.075 31.746 50.930 
B—First two inches- 7,513 0 36.062 161.814 259.598 
O—First two inches-20,544.0 12.326 55.308 88.730' 
D—First two inches_ 8,000.0 19.200 86.152 138.214 
A—Second two inches. Trace Trace . 
B—Second two inches.. 3,890.0 0.389 1.745 2.800 
C—Second two inches.. 8,130.0 1.626 7.296 11.705 
D—Second two inches.. 8,640.0 2.073 9.306 14.929 
§ 93. This indicates that, at the time these samples were 
taken, a very small percentage of the total nitrogen existed in the 
soil in the form of nitrates, and that the first two inches of this soil 
was at the time very much richer in nitrates than the second, also 
that different portions of the plot contained very different amounts, 
of these salts. 
DO SOIL SAMPLES ABSORB NITROGEN ON KEEPING? 
I * 
§ 94. The most of the nitrogen determinations given in this 
bulletin were made on fresh samples, but occasionally we found it 
desirable to check a determination on an old sample, one that 
had been in the sample room for one or more years. The samples 
are kept with ordinary care, but not always sealed. The samples 
which suggested this question had been carefully stoppered and 
kept two years, but had not been sealed. In order to answer this 
question, a sample was taken and the nitrogen determined in dupli¬ 
cate. The remaining portion of the sample was dried as usual, bot¬ 
tled, corked and kept in the laboratory for fifteen months and the 
nitrogen redetermined in duplicate. The average of the first two 
determinations was 0.1058 per cent., that of the last two 0.1066 per 
cent. The difference is 0.0008 per cent., which is possibly to be 
attributed to analytical differences, rather than to the absorption of 
nitrogen in any form from the atmosphere of the laboratory. If r 
however, we accept the analytical results as correct, they show that 
the sample gained a quantity of nitrogen, due to increase of micro¬ 
organisms, corresponding to 28 pounds per acre, taken to a depth 
of one foot. 
HUMUS IN THE SOIL. 
§ 95. The humus in this soil is not especially low, as is the 
rule with our soils in general. The earlier determinations being 
slightly under one per cent., while the later ones average about one 
and one tenth per cent., a gain of about three tenths of one per cent. 
I thought that the physical condition of the soil and the presence of 
so large an amount of soluble salts would probably modify the 
character of the humus to a sufficient extent to cause some marked 
changes in properties or composition sufficient to justify its analysis. 
This was not found to be the case. The humus is very much like 
