20 
The Colorado Experiment Station, 
the ocean, and with the gradual rising of the western coast, these 
bodies of water became inland seas, which could be replenished only 
at high tide. Quantities of sea-weed are supposed to have grown 
in these shallow basins, and after decomposing, their nitrogen was 
changed by nitrifying bacteria into nitrates. The high tempera¬ 
ture, the lack of rainfall and the absence of an outlet all assisted 
in the concentration of the nitrate in these areas until the material 
which accumulated reached into the millions of tons. 
Thus, through the agency of microorganisms by the processes 
of ammonification and nitrification, the unavailable nitrogen of 
decomposing organic matter is changed into nitrates and restored 
to the soil in a form which is indispensable to all plant life. 
Nitrification* in Colorado soils is a topic to which we have 
given considerable attention during the past year because of its 
relation to the niter trouble which is discussed on page — of this 
paper. The results of the investigation indicate that this process 
goes on much more actively in our soils than in many soils from 
other parts of the United States. Work which is in progress at 
the present time may shed some light upon this point, but just 
now we cannot say whether it is due to peculiar soil conditions 
which are especially suited to the development of the nitrifying 
organisms, or possibly, to the presence of new species of bacteria 
which are exceptionally alert biochemically. This difference in 
nitrifying efficiency is illustrated very well in Table 2 which gives 
the net gain in nitrates made by Colorado and foreign soils when 
supplied with ammonia nitrogen in the form of ammonium sul- 
phat and ammonium carbonate. 
Table No. 2. Nitrification of Ammonium Sulphate and Ammonium 
Carbonate by Colorado and Foreign Soils. 
Source and character Net gain in nitrates per million 
of soil. parts of air-dried soil from 100 
m. g. ammonia nitrogen as: 
Ammonium Ammon i uni 
sulphate. carbonate. 
Colorado; wheat field; clay; normal. 3258 2899 
Colorado; peach orchard; heavy clay ; 
normal .. 3681 . 2620 
Colorado; apple • orchard; heavy clay; 
niter .,.. 4302 2 798 
*The detailed account of this investigation has been published as Bulletin 193, Colo. Exp. 
Sta., “The Nitrifying Efficiency of Certain Colorado Soils,’’ January. 1914. 
