42 
Bulletin 72. 
The presence of larger quantities of nitrites in the drain than in 
the ground water is more probably due to the deportment of the 
solution of these salts within the soil than to a reduction of the 
nitrates. This view is suggested by the facts stated above, and also 
by the fact that the off-flow water is poorer in nitrates than the 
ground water either before or after irrigation, while the nitrites in 
the off flow water amounted to more than 200 times as much as was 
found in the ground water, but the amount was less than that which 
was found in the drain waters. I do not maintain that there is no 
reduction of the nitric to nitrous acid taking place in this soil, but 
simply that the appearance of the nitrous acid in the drain and 
off flow water in excess of the nitrates does not necessarily indicate 
a reduction of the nitric acid, but is probably to be explained in 
this case by the different deportment of these salts after they have 
been formed, without regard to the method of their formation. I 
stated in a former paragraph that I had no reason to assume the 
formation of ferrous salts or the presence of other conditions favor¬ 
ing the reduction of the nitrates in any unusual degree, micro 
organisms not included. 
AMMONIA IN THE GROUND WATER. 
§ 120. The ammonia and ammonia salts in the soil were 
shown in Bulletin 65 to probably amount to a little more than 
0.00211 per cent, of the soil. The amount of these salts in the 
ground water is small, ranging from 0.0230 to 0.0850 part per mil¬ 
lion. Irrigation increased this amount to from 0 0570 to 0.5780 part 
per million. The drain waters were found to contain from 0.0496 
to 0.0944 part per million. 
§ 121. The albumenoidal ammonia present ranged from 
0.0674 to 0.3029 part per million in the ground water and was 
greatly increased by irrigation. The maximum found after irriga¬ 
tion was 3.1170 parts per million. This kind of ammonia does not 
pass into the drain very freely ; it amounted to 0.2299 part per mil¬ 
lion in the drain water from this plot. The comparatively small 
amount of ammonia found in the drain waters strengthen the state¬ 
ment made relative to the reduction of the nitrates to nitrites. The 
reader may be tempted to think that we intend to discuss the pota¬ 
bility of this water. Such is not the case. It is purely a matter of 
the soil conditions. It is for this reason that certain properties of 
the water are not discussed at all. 
AMOUNT OF NITRATES, ETC., REMOVED BY THE IRRIGATION WATER. 
§ 122. The question as to how much of the nitrates, nitrites, 
and ammonia of both kinds was taken from the soil by the water 
naturally suggests itself. This question is difficult to answer in re¬ 
gard to the ground water, for there are a number of considerations 
