Jan. 31,1916 Bacterial Activity in Soils and Crop Production 
861 
TESTS ON ROTATION PEOTS IN 1912 
The same series of plots was used in 1912 in the study of the relative 
effects of different rotations on bacterial activities and on crop produc¬ 
tion, but in some cases different individual plots were employed, as again 
only those which were cropped to corn were examined. 
Ammonification tests were carried out by the dried-blood-air-dry-soil 
method with inoculum from fresh soil, the casein-fresh-soil method, and 
the dried-blood-fresh-soil jnethod. The nitrifying power was tested by 
the ammonium-sulphate-air-dry-soil method and the ammonium-sul¬ 
phate-fresh-soil method. These methods were under investigation at 
the time of this study, and comparative tests of their efficiency have been 
reported in the work already referred to. 1 
Four samplings were made during the year—on August 9, August 19, 
October 7, and October 26. The variations in moisture content of the 
soils at the various dates were so slight that the differences observed 
could not be attributed to that factor, and the results of the determina¬ 
tions are not included here. 
The crop yields were obtained from the plots as in the previous year. 
The ammonification results appear in Tables VII, VIII, and IX, the 
nitrification results in Tables X and XI, and the crop yields are given in 
Table XII. 
Table VII. —Ammonification of dried blood in air-dry soil of rotation plots in 1912 
Quantity of ammonia (in milligrams of nitrogen). 
Plot No. 
Test 1. 
Test 2. 
Test 3. 
Test 4. 
601. 
148. 33 
157- 55 
170. 69 
172. 6c; 
168.53 
151.27 
161. 08 
54. 93 
66.31 
79* 77 
82. 40 
75* 73 
64.15 
71. 61 
124.78 
130.27 
138.71 
141.85 
136- 95 
125. 17 
13 I. 06 
122. 42 
127.92 
138. 71 
143. 42 
' I3°* 67 
119. 09 
138. 21 
602. 
605. 
608. 
610. 
002. 
004.. 
Table VIII. —Ammonification of dried blood in fresh soil of rotation plots in 1912 
Quantity of ammonia (in milligrams of nitrogen). 
Plot No. 
Test 1. 
Test 2. 
Tests. 
Test 4. 
106. 34 
68. 66 
5°. 81 
54-74 
no. 66 
80. 05 
65. 14 
62.39 
117.32 
86. 70 
73* 77 
71. 02 
120. 87 
88.28 
74. 02 
74.66 
US-95 
78.87 
72. 59 
71.41 
109. 67 
73- 38 
58. 86 
62.19 
114. 14 
82. 9O 
68. 28 
69.17 
1 Brown, P. E- Op. cit. 
