26 
Colorado Experiment Station 
and as round as a circle. Inside this circle there is more nitrogen and 
ttiiore nitrates than outside of it. These spots are not always small; 
they may cover a whole section of land or several sections. In such 
cases the nitrates are, of course, not evenly distributed forming one 
continuous bed of nitrates, still last year, 1916, I saw a section of land 
that had been planted to peas in which the nitrates were abundant 
enough to kill practically all of them. As said in the quotation given 
above, from our Bulletin No. 155, these spots and larger areas are not 
confined to one particular geological formation, nor so related to any 
given one that we can say that the formation has anything to do with 
them. Shales occur in great quantities within our State and some 
of our valleys are both bordered and underlaid by them, so it is quite 
proper to speak of shales in this connection, 'but I have met with these 
nitre spots, both above and below the shales and where there are no 
shales at all, so we could not, without leaving out part of the facts, say 
that they come from the shales, even if we had some good reason for 
believing that they really are present in the shales. I pointed out in 
Bulletin No. 155 that some shales carry nitrates and explained how 
these nitrates could have got there; in fact, they ought to be there, and 
we would have to explain how it happened if they were not. These 
nitrates occur in the surface portions of some sandstones, also of lime¬ 
stones and volcanic rocks. Some ammonic compounds have been found 
in the gases which accompany volcanic eruptions and these may later 
be converted into nitrates by certain living organisms, but the proper¬ 
ties of these nitrates forbid their being an original part of a molten 
rock, especially if the rock is acid or contains quartz. If we find ni¬ 
trates in such rocks, as well as in sandstones or in limestones, they do 
not belong to the rock proper and they are not in the deeper portions 
of the rock, but only in the surface portions. 
We know that the small amounts of nitrates found in soils are 
formed there. It has been worked out that if we put animal matter, 
fish, or dried blood, for instance, containing nitrogen, on the soil, the 
nitrogen contained in it is broken out, converted into new forms 
and, while some of it may go off into the atmosphere as nitrogen gas, 
most of it is oxidized or burned to nitric acid. If we added enough 
fish or blood or other nitrogen-carrying matter, and kept our soil con¬ 
ditions favorable, we could make the soil carry several percent of ni¬ 
trates. 
The question is not how the nitrates may be formed in the soil but 
Where does the nitrogen contained in them come from? This is the 
question that bothers us. 
I have stated in the preceding some reasons why I do not believe that 
the nitrates come from the rocks or from the waters. In fact, it would 
