22 
The above results show the low fixing power of this type of soil 
for nitrates. This fact strongly indicates the r61e of organic matter 
in the absorption of this salt. The organic matter content of the 
previous series of soils was much higher than that of the red clay. 
There was apparently no difference between the fixing power of the 
soil and the subsoil, but it was stronger in the fresh than in the air- 
dried samples. 
ABSORPTION OF FERTILIZER SALTS WHEN APPLIED IN MIX- 
TURES, AND THE EFFECT OF HEAT AND ANTISEPTICS. 
A third series of experiments was made with the idea in mind of 
applying a solution containing a mixture of fertilizer salts and at the 
same time determining the effect of heat and volatile antiseptics 
upon the absorbing power. The soils chosen for this series were No. 
428, a highly organic soil used in the first series, and No. 517, the red 
clay soil used in the second series. Three fertilizer mixtures were 
used and applied to the soil in series of three, namely, untreated, 
heated (230° C. in air bath), and partially sterilized (5 cubic centi- 
meters chloroform to 100 grams soil kept in a closed fruit jar 48 
hours, then spread out in the air 24 hours before placing in the glass 
tubes). The mixtures were as follows: (1) ammonium sulphate, 
potassium phosphate, and potassium sulphate; (2) ammonium 
sulphate, calcium phosphate, and potassium sulphate; and (3) 
sodium nitrate, calcium phosphate, and potassium sulphate. The 
solutions were allowed to percolate through the soil at the rate of 100 
cubic centimeters in 24 hours, and the percolates were analyzed. 
ABSORPTION OF PHOSPHORIC ACID. 
The table following shows the fixing power of these soils for phos- 
phoric acid when applied in mixtures. 
