12 
Colorado Experiment Station 
We will assume that the plants take up all of their nitrogen in 
the form of nitrates so that the total amount of nitrogen is not so 
much the question as the rate of nitrification or the rate at which the 
nitrogen present may become available as plant food. Experiments 
made with this soil indicate a high power in this direction. The 
nitric nitrogen was determined at the time of planting and at inter¬ 
vals throughout the season of 1913, i. e., during the growth of the 
crop. We found at the time of planting very varying results, so 
much so that any statement relative to the amount of nitrates present 
not be correct for any other than the particular area taken. With 
this understanding it may be stated that the approximate amount of 
nitric nitrogen present at the time of planting was, for 'the two feet 
for which the phosphoric acid and potash has been calculated, about 
35.16 pounds, corresponding to 211 pounds of sodic nitrate per acre. 
This amount of nitrogen was at that time available and capable of 
being appropriated by the young plants. 
We used the three conventional solvents in our endeavor to ob¬ 
tain some data pertaining to the availability of the phosphoric acid 
and potash: hydric chlorid, 1.115 specific gravity; citric acid, 1 per¬ 
cent solution; and one-fifth normal nitric acid. These solvents, in 
the order given, indicated the presence of the following quantities of 
these two substances in the first two 1 feet of the soil. 
Hydrochloric acid 
Citric acid . 
N-5 Nitric acid . 
Potash Phosphoric 
Pounds acid—Pounds 
51,520 9,880 
1,960 1,440 
3,080 5,560 
These quantities indicate a sufficiency of available plant foods to 
grow a large number of maximum crops, and explain the fact 
that the addition of phosphoric acid and potash, even in very liberal 
quantities, did not produce any observable effects upon the growing 
plants and only very small effects upon the yield of grain. These are 
so small that it is only by adhering to a very literal interpretation of 
the results that we can justify ourselves in claiming any advantage 
in crop from their use. There is no big, decisive and easily inter¬ 
preted result produced by their application. 
These analytical data are the basis of all of our experiments. 
They are as satisfactory as any others that we would be likely to ob¬ 
tain, for the mineralogical character of our soil makes it practically 
impossible to obtain any better or more concordant results, or others 
which might be more easily interpreted. This soil is exceedingly rich 
in felspathic sand. The felspar present is for the most part an ortho- 
clase with some microcline. These minerals are readily attacked by 
decomposing agents, the action of water and carbon dioxide being 
