934 
Journal of Agricultural Research 
Vol. XXIV, No. II 
XabIvB XIII. CoYYip(iris 071 of the preseficc of A-zotobocter, fiitrogofi fixed, and reaction 
of same soils collected 2 years apart 
Soil No. 
Azotobacter. 
Nitrogen fixed. 
Colorimetric 
Ph. 
Electrometric 
Ph. 
1918 
1920 
1918 
1920 
1918 
1920 
1918 
1920 
1918 
1920 
Mgm. 
Mgm. 
I. 
lOI 
+ 
4 ~ 
10.3 
10. 7 
6.9 
6.7 
6.71 
2. 
102 
— 
— 
2.0 
6.3 
5.4 
5.0 
3-78 
3 . 
103 
— 
— 
3-0 
5-4 
5*6 
5*4 
5-27 
4. 
104 
-f 
6.8 
10. g 
6 0 
*7 T 
5 . 
105 
4 - 
4 - 
5-4 
II.8 
7*1 
7.2 
7.08 
6. 
106 
— 
— 
4.4 
6.1 
5.7 
5*7 
5.25 
15. 
133 
+ 
+ 
10.3 
13.5 
7*4 
7.3 
7.45 
16. 
136 
— 
+ ? 
4.0 
10.5 
5.6 
5-4 
4.88 
17. 
137 
— 
— 
3-0 
4.3 
5-5 
5.8 
5.58 
18. 
138 
— 
— 
3*7 
3-0 
5.6 
5.4 
5.05 
31. 
107 
4 - 
4 - 
10.6 
10.2 
7-5 
7.4 
7.71 
7.70 
32. 
108 
— 
4 -? 
5.6 
8.5 
5.9 
5.6 
5-85 
5.48 
33 . 
109 
— 
4 - 
4.0 
9*5 
6.7 
6.6 
6.56 
6.47 
34 . 
no 
— 
4 - 1 
4.5 
7*9 
6.8 
7*4 
6.74 
7.61 
35 . 
III 
4 - 
4 - 
6.8 
9.1 
7.6 
6.6 
7.62 
6.39 
36.. 
II3 
4 - 
4 - 
9.2 
8.9 
6.0 
5.6 
6.12 
5.85 
37 . 
114 
— 
4 - 
5.4 
8.9 
6.2 
5.8 
6.07 
5.59 
38. 
II5 
— 
4 - 
3-9 
8.6 
5*6 
5.4 
5-59 
5.51 
39 . 
II6 
4 - 
4 - 
8.6 
10.0 
6.1 
6.0 
6.05 
5.90 
40. 
II9 
4 - 
4 - 
8.1 
9.8 
7.0 
7*1 
6.72 
7.00 
49 . 
126 
— 
2.7 
8.0 
5.5 
5-5 
5.03 
519 
50. 
127 
— 
— 
4.0 
6.6 
5.8 
5-5 
5.32 
5.10 
SI. 
128 
— 
3-2 
5.1 
5-3 
5-9 
5-41 
5.78 
52. 
129 
4- 
4- 
5.5 
10.8 
7-3 
7.6 
7.27 
7.30 
S 3 . 
130 
4- 
4- 
9.0 
7.3 
7.7 
7'4 
7-79 
7.52 
54 . 
131 
4- 
— 
7-4 
7.7 
6.0 
5.8 
6.08 
5.47 
61. 
120 
— 
4- 
3-7 
6.0 
5-5 
5-8 
5.51 
5.68 
63. 
124 
+ 
4- 
II.0 
9.0 
7-4 
6.9 
7.43 
7.06 
64. 
122 
4- 
4-? 
8.3 
8.6 
6.1 
5-8 
6-35 
5.51 
65. 
123 
— 
4- 
5.2 
8.8 
5.7 
5-9 
S -94 
5.64 
66. 
I 2 I 
— 
— 
3.8 
7.6 
5-7 
5.7 
5.81 
5.24 
77 . 
134 
— 
— 
4.2 
7.2 
5-6 
5-4 
5-34 
4.88 
79 . 
143 
+ 
4- 
7.6 
7.0 
7.7 
8.1 
8.48 
8.77 
80.. 
144 
4- 
4- 
9.2 
8.8 
7.6 
7.3 
7.84 
7.72 
82. 
142 
+ 
4- 
8.2 
9.7 
7-7 
7.8 
7.60 
7-59 
83 . 
145 
4- 
4 * 
9.9 
7-5 
7.6 
7.2 
7.72 
7.94 
TabIv^ XIV .—The nurriber and percentage of soils of various reactions containing A zotohacter 
Electrometric. 
Colorimetric. 
Ph reaction. 
Num¬ 
ber of 
soils. 
Azotobacter, 
Num¬ 
ber of 
soils. 
Azotobacter. 
Present. 
Absent. 
Present. 
Absent. 
Above 7.50. 
57 
No. 
57 
Per 
cent. 
100 
No. 
0 
Per 
cent. 
0 
32 
No. 
32 
Per 
cent. 
100 
No. 
0 
Per 
cent. 
0 
7.00 to 7.49 .... 
49 
45 
92 
4 
8 
60 
58 
97 
2 
3 
6.50 to 6.99 .... 
33 
27 
82 
6 
18 
45 
39 
90 
6 
10 
6.00 to 6.49 .... 
38 
30 
80 
'8 
20 
47 
37 
80 
10 
20 
5.50 to 5.99- 
64 
22 
34 
42 
66 
122 
24 
20 
98 
80 
5.00 to 5.49 .... 
75 
7 
9 
68 
91 
43 
6 
14 
37 
86 
4.50 to 4.99 . . . . 
42 
5 
12 
37 
88 
44 
3 
7 
41 
93 
Below 4.50. 
16 
0 
0 
16 
100 
3 
0 
0 
3 
100 
Total .... 
374 
193 
181 
396 
199 
197 
