Fertilizer Treatment 305 
0 
results as measured by this test seemed to show the nitrifying power 
of these soils to be very similar. 
Comparing Tables 4 and 5 the results show that the nitrates in 
the ammonium sulphate treated samples were increased more for the 
fertilizer plots Nos. 7, 10, and 12 which received no nitrogen in their 
treatments, than were the nitrates for plots Nos. 4, 6, 8, and 11, which 
received nitrogen in their treatments. The average difference due to 
increase for the plots receiving no nitrogen in their treatments was 
15.98. But the average difference for the plots receiving nitrogen in 
their treatments was only 12.74. The average difference due to in- 
crease was a little lower for the check plots, it being 12.12. The 
greatest increase occurred in the case of the manure plots which had 
an average difference of 22.12. 
The results of this test seem to indicate that manure treated soil 
has the strongest nitrifying power because of the increased physiologi- 
cal efficiency of the bacteria. The check plot shows the lowest nitrifying 
power due to the lowered physiological efficiency of the bacteria. The 
treatment with phosphorus, potassium or both increased the nitrifying 
power of the soil. The nitrogen applied in the form of ammonium 
sulphate at the time this test was started made doubtful the effect of 
the original nitrogen treatments on the nitrifying power of the soils. 
TABLE 8. 
Table of Averages. 
Nitrate Parts Per Million Millions Per Gram of Dry Soil 
on Dry Basis Calculated on Dry Basis 
Plot Per Cent |Per Cent|— — 
No. Volatile | Moisture After 2 Weeks} After 2 Weeks 
Matter Fresh Soil Incubation Incubation Bacteria Molds 
Plus (NH,)280s 
1 6.10 16.13 14.26 29.42 38.10 4.880 .605 
2 6.15 18.29 18.97 42.62 64.12 6.543 641 
3 5.91 18.70 21.47 44.80 67.55 7.795 .726 
4 5.62 19.39 13.86 29.47 39.39 5.604 .521 
5 5.75 17.07 9.90 27.47 32.20 3.895 .584 
6 5.52 17.66 13.11 25.75 37.12 4.205 .903 
7 5.90 18.17 1s 25.19 39.82 4.899 .629 
8 5.68 Liva2 13.90 27.67 44.99 5.730 .645 
9 5.75 17.20 12.39 25.23 45.13 4.035 .428 
10 5.66 17.03 13.80 24.53 42.02 4.996 .613 
11 5.66 16.15 12.80 22.99 35.35 5.270 .469 
12 5.69 16.50 iB ly 21.56 37.38 4.230 .563 
13 5.86 16.82 11.50 22.51 37.47 3.964 . 661 
TABLE OF AVERAGES (Table 8). 
Since it seemed that the plot averages for the period were a more 
accurate measure of the nitrate producing ability of the plots than 
figures for any one month, these plot averages for all the tests were 
brought together in Table 8. A study of this table as illustrated by 
Figure I shows that there is a direct correlation between bacterial 
activities and nitrate production. The nitrates were low in the fresh 
soil and correspondingly higher in the incubated soil. The highest ni- 
trate production occurred in the ammonium sulphate treated soils. 
Bacteria and mold counts correlate closely, bacteria having the much 
higher count. 
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