308 Proceedings Indiana Academy of Science 
least correlation. Plot No. 3 has the highest efficiency factor and its 
corn yield was lowest of all the plots. Again in Plot No. 4 the effi- 
ciency factor goes down and the corn yield is highest of all the plot 
yields. However, for the remainder of the plots the yield and the 
efficiency factor show a close agreement. 
SUMMARY. 
A general study of the results of this experiment seem to show that 
the manure plots which were high in mold counts; highest in_ bac- 
terial numbers; highest for fresh nitrates; equally high in incubated 
nitrates and very high in the ammonium sulphate treated samples, had 
the greatest efficiency for nitrate production. The cow manure treat- 
ment seemed to be somewhat more efficient than the horse manure 
treatment since the results of all tests were slightly higher in its favor. 
Check plot No. 1, seemed to have been influenced by the manure 
treatment due to its nearness to those plots. The results from plot 1 
usually were as high or higher than the average for all the plots and 
on the whole higher than the other check plots. 
The use of nitrogen with phosphorus or potassium was superior 
to either of the treatments used alone for bacterial count and all ni- 
trate tests except the ammonium sulphate treated samples where the 
difference was slight. Phosphorus and potassium treatments increased 
mold and bacteria growth, fresh nitrates and ammonium sulphate 
treated samples. 
The results of ammonium sulphate treated samples which were 
least influenced by crop growth and seasonal variations seem to show 
that the greatest nitrifying power of a soil is in May, June and July. 
This power seems to decrease during the latter part of the summer and 
increase in the late fall and spring. 
There seems to be a general correlation, when averages are taken 
for the entire season, between the amount of nitrate found in the soil 
under natural conditions with growing crops and the amount accumu- 
lating under optimum conditions. Purdue University. 
BIBLIOGRAPHY. . 
1, Gibbs, W. M. 1919 
The Isolation and Study of Nitrifying Bacteria Soil. Science Vol. VIII, No. 6. 
2. King, P. H. and Whitson, A. A. 1901 
Development and Distribution of Nitrates and Other Soluble Salts in Cultivated 
Soils. Wisconsin Agr. Experiment Station Bulletin 85. 
3. Voorhees, E. B. 1907 
A review of Investigations in Soil Bacteriology. U. S. D. A. Bulletin 194. 
4. Brown, P. E. 1913 
Methods of Bacteriological Examination of Soil, Iowa State College Research 
Bulletin 11. 
5. Lyon, ,T. L.; Bizzell, J. A., and Conn, H. J. 1913 
An examination of Some More Productive and Some Less Productive Sections 
of a Field. Bulletin 338, Cornell University. 
6. McLean, H. C., and Wilson, G. W. 1914 
; Ammonification Studies With Soil Fungi. New Jersey Agricultural Exp. Sta. 
Bulletin 270. 
