31 
matter reacted with the nitrate solution, as the effect of this solution 
on the soil was quite marked. 
The series showing the relation of the fixing power of soil and sub- 
soil, and the effect of drying in the air, gave only slight differences. 
It was found, however, that phosphoric acid was fixed more strongly 
by the fresh soil, but there was scarcely any difference between the 
soil and subsoil. This is probably due to the fact that there is little, 
if any, difference in the mechanical condition of soil and subsoil in 
this red clay type, and also very little difference in chemical compo- 
sition. The fixation of potash was higher in the air-dried soil, as 
previously explained, and higher in the subsoil than the soil. The 
ammonium nitrogen, strange to say, unlike the potash, was more 
strongly fixed by the fresh soil, which indicates the possibility of cer- 
tain organisms affecting the fixation. The subsoil had a higher fixing 
power than the soil. There probably are also organisms acting as 
fixing agents for the nitrates, as the fresh samples had a higher fixing 
power than the air dry, while there was no difference in that of the 
soil and subsoil. 
The most striking results are those obtained from the series in which 
a solution of mixed fertilizer was used. From the data at hand the 
conclusion is thought justified that the least waste is to be had by 
application of fertilizer salts singly rather than in mixtures. When 
the salts were applied singly there was a marked loss of potash, a 
decrease in amount of ammonium nitrogen fixed, a decrease in nitrate 
nitrogen, and a decrease in phosphates in case of the red clay, but 
scarcely any difference with the organic soil. However, there was no 
deflocculation of the soil when the salts were added in mixtures, except 
to a small extent in the mixtures which contained potassium phos- 
phate. In this instance the percolates came through cloudy — that 
is, they contained deflocculated clay. On the other hand, the extracts 
in which the calcium salt was used were perfectly clear and colorless. 
Again, all the percolations proceeded quite rapidly, while several of 
the salts, the phosphates in particular, when used alone, would not 
allow a solution to pass through a column of soil. Solutions contain- 
ing potassium phosphate percolated more slowly than those contain- 
ing calcium phosphate. 
The effect of heat and antiseptics was not very striking and the 
results were not very consistent. In one instance, a highly organic 
soil, heat decreased the fixing power for phosphoric acid, while in 
general it decreased the fixing power for potash, ammonium nitrogen, 
and nitrate nitrogen. The effect of chloroform on the fixation of the 
first three elements was negligible, while it increased the fixing power 
for nitrates. 
