52 
Journal of Agricultural Research 
Vol. VII, No. a 
agency of nitrification. Out of 49 foreign soils, about 9 of which should 
be reckoned as arid rather than humid, 30, or about 61 per cent of the 
whole number, contain more than 0.1 per cent of total nitrogen (only 
in very small part, including nitrates). If allowances are made for the arid 
or semiarid soils among the foreign soils, about three-quarters of the soils 
from the humid region are found to contain more than 0.1 per cent of 
nitrogen. Only 8 soils, or about 14 per cent of the total of 49, contain 
less than 0.05 per cent of nitrogen each, and 4 of these belong properly 
to the arid or semiarid class. Only 2 soils contain less than 0.03 per 
cent total nitrogen, but neither of these is an arid soil. These figures 
are very interesting and worth remembering for comparison later with 
similar statistics anent the California soils. The second column of 
figures in Group I of Table I can be made to show percentages of total 
nitrogen by moving the decimal point three places to the left. 
With respect to the absolute quantities of nitrate produced, only 16 
out of 47 soils tested produced from their own nitrogen less than 10 
mgm. of nitrate nitrogen, and only 2 of them produced less than 5 mgm. 
of nitrate nitrogen in the same period. No relationship whatever is 
discernible between the total amount of nitrogen present in the soil 
and the amount which was rendered into nitrate. About two-thirds of 
the soils tested were therefore able to produce in every case more than 
10 mgm. of nitrate nitrogen in a month's incubation period. Likewise, 
nearly two-thirds of the soils tested rendered more than 10 per cent of 
the nitrogen present in the soil into nitrate, and several more approached 
the 10 per cent mark very closely. Moreover, nearly 40 per cent of the 
soils tested transformed in every case more than 15 per cent of the 
total nitrogen present into nitrate. If the few characteristically arid 
or semiarid soils among the foreign soils are disregarded, less than 35 
per cent of the soils would fall in the class last named. It is also of 
great interest to note that over 12 per cent of the soils tested trans¬ 
formed more than 30 per cent of the nitrogen in them into nitrate 
under the circumstances noted; and two of the soils, the Delaware and 
Nebraska samples, transformed into nitrate more than 50 per cent 
of the nitrogen which they contain. It may be purely a matter 
of coincidental interest but possibly worthy of note that of the 9 soils 
which transformed between 20+ per cent and 38+ per cent of their 
nitrogen into nitrate, thus placing them in a class next to the two very 
exceptional soils just referred to, 7 belong to the Southern or South Atlan¬ 
tic group of States, and the other 2 are from New Mexico and Nevada, 
which more properly belong with the arid or semiarid group. 
The results obtained when sulphate of ammonia is added to the soil 
nitrogen and the whole incubated are found to be opposite to that taken 
by the data for soil nitrogen. The addition of sulphate of ammonia to the 
foreign soil has not induced, as might be expected, an increase in the 
production of nitrate over that produced from the soil's nitrogen alone, 
