THE NITRIFYING EFFICIENCY OF CERTAIN COLORADO SOILS 
13 
and nearly every third tree in the twenty acres had been killed and 
removed. When I visited here in May, 1913, young apple trees had 
been set out where the old trees were missing. I have mot been back 
since to see if they survived the summer, but I should be surprised 
if they did. Red clover had been sown between the trees as a shade 
crop, but the stand was very scattering. 
My sample was collected about two feet from a hole where a dead 
tree, presumably killed by niter, had been taken out. When the nitric 
nitrogen was determined, I was very much surprised to find that it 
contained but 5 p. p. m. with 1000 p. p. m. of chlorin. That the ni¬ 
trates in this soil had been considerably above normal in 1910, there 
is no question, for at that time Dr. Headden found in the surface-three 
inches 4.902 per cent, of water soluble salts to be nitrates, the water 
soluble amounting to 2.92 per cent, of the air-dried soil. I am at a 
loss to explain the low figure that I obtained unless it is that I was mis¬ 
led by the hole where the tree was missing into thinking that it was a 
niter tree when, in reality, it had died from another cause, or else, 
I just happened to take the sample from a spot where the excessive 
nitrates had not yet developed. As mentioned before, there was no 
brown color apparent on this red soil, to guide one either in picking 
out or in avoiding the bad places. 
Sample No. 80 .—In our study of this question we are continually 
meeting land-owners who believe that the difficulty can be remedied 
by proper drainage. The present case is only one of several that 
could be cited to show that little relief follows the installation of a 
drainage system. It is difficult to see how it could be otherwise, since 
the accumulation of nitrates does .not appear to be a question of drain¬ 
age ; again, it has been found to be practically impossible to drain the 
heavier niter soils because of their sticky, gumbo character; and 
furthermore, in the majority of instances, draining is not indicated and 
is unnecessary. However, in the case at hand, the owner employed an 
experienced engineer to put in the 'necessary amount of tile at the 
proper depth and with the correct fall and distribution. 
A part of the orchard was manifestly seeped as indicated by the 
white alkali on the surface, and this condition was; remedied con¬ 
siderably by the drain, but so far as checking the progress of the niter 
destruction, nothing had been accomplished. 
When I collected my sample, on the thirteenth of May, 1913, 
about one-third of the trees were dead and the barren spots had been 
reset with young stock. The soil is a clay loam and where the sample 
was taken the surface was very fine and mealy. Because of this condi¬ 
tion, the surface-inch was removed and the second to fifth inch used. 
The nitric nitrogen present amounted to 13 p. p. m. and the chlorin 
to 10,400 p. p. m. As in the preceding orchard, we have observed 
here also in previous years that the burning was moderate and that 
the trees were succumbing slowly. This was probably due to the fact 
that the nitrates were accumulating more gradually than in other lo¬ 
calities where damage had been more acute. 
Sample No. 81. — This soil came from a field which had been 
