56 
Journal of Agricultural Research 
Vol. VII, No. 2 
Table III .—Nitrification in types from the Bay area series 
Soil type. 
Soil nitrogen 
(Group I). 
Soil nitrogen and 
sulphate of am¬ 
monia (Group II). 
Soil nitrogen and 
dried blood 
(Group III). 
Soil nitrogen and 
cottonseed meal 
(Group IV). 
Ni¬ 
trate 
pro¬ 
duced. 
Total 
nitro¬ 
gen 
in 
soil. 
Ni¬ 
tro¬ 
gen 
nitri¬ 
fied. 
Ni¬ 
trate 
pro¬ 
duced. 
Total 
nitro¬ 
gen 
in 
soil. 
Ni¬ 
tro¬ 
gen 
nitri¬ 
fied. 
Ni¬ 
trate 
pro¬ 
duced. 
Total 
nitro¬ 
gen 
in 
soil. 
Ni¬ 
tro¬ 
gen 
nitri¬ 
fied. 
Ni¬ 
trate 
pro¬ 
duced. 
Total 
nitro¬ 
gen 
in 
soil. 
Ni¬ 
tro¬ 
gen 
nitri¬ 
fied. 
Mgm. 
Mgm, 
P.ct. 
Mgm. 
Mgm. 
P.ct. 
Mgm. 
Mgm. 
P.ct . 
Mgm. 
Mgm. 
P.ct. 
Tidal marsh clay. 
Tr. 
1+ 
Tr 
5-oo 
9 - 75 
Altamont heavy loam. 
2-35 
112.00 
2+ 
7 - 75 
152.00 
5+ 
14- 75 
244.00 
64 - 
159-00 
64 - 
Yolo silty clay loam... 
1.20 
93.80 
1+ 
.80 
133-80 
Tr. 
. 60 
225.80 
Tr. 
*45 
140.80 
Tr. 
Dublin clay adobe.... 
1*50 
65.80 
2+ 
4 - 00 
105.80 
3 + 
4.00 
197.80 
2-h 
6.00 
112.80 
5 + 
Dune sand. 
.80 
35 *oo 
2+ 
.72 
75 -oo 
Tr. 
167.00 
1. 20 
82.00 
1+ 
Oakley light sandy 
loam. 
3-oo 
51-80 
5 + 
4.00 
91.80 
4+ 
—1.00 
183.80 
3-50 
98.80 
3 + 
Altamont clay adobe.. 
•30 
50.40 
Tr. 
.40 
90.40 
Tr. 
182.40 
97-40 
Diablo clay adobe. 
2.00 
6s-80 
3+ 
12.00 
105.80 
1+ 
7.80 
197.80 
3 + 
8.00 
112. 80 
7 + 
Residual day adobe... 
3 *oo 
116.20 
2+ 
3*00 
156.20 
1+ 
3.00 
248.20 
1+ 
2. 50 
163.20 
1+ 
Santa Rosa loam. 
• 9 c 
86.80 
1+ 
4 * 50 
126.80 
3 + 
9.50 
218.80 
44 - 
7 - 50 
133- 80 
5 + 
Altamont light types.. 
3.00 
72.80 
4 + 
3-oo 
112.80 
2+ 
204.80 
7.00 
119.8c 
5 + 
No. 150 Brown type 
heavy loam. 
5 - 50 
183.40 
2-f 
20.90 
223-40 
9 + 
x8. <0 
3 * 5 - 40 
5 + 
II- 50 
230.40 
4 + 
Tuscan stony loam.... 
•43 
32.20 
1+ 
•43 
72.20 
Tr. 
2.13 
164.20 
14 - 
- 63I 
79. 20 
Tr. 
Do. 
I.40 
138,60 
1+ 
5-30 
178.60 
2+ 
4.80 
270.60 
1 4 - 
4-30 
185.60 
24 * 
Santa Rosa loam. 
i -57 
61.60 
1.28 
roi. 60 
2 + 
193.60 
.48 
to8 . 60 
Tr. 
No. 150 Gray phase 
loams. 
1.80 
82.60 
2+ 
1.80 
122.60 
1 + 
.60 
214.60 
Tr. 
5-10 
129.60 
3 + 
Newark loam. 
4.10 
75.60 
5 + 
4*30 
115.60 
3 + 
25.90 
207.60 
12+ 
6.10 
122.60 
4 + 
Antioch loams and 
clay loams. 
4-36 
72.80 
5 + 
6. 56 
112. 80 
5 + 
15.96 
204.80 
7 + 
16.96 
119. 80 
14+ 
No. 12 black phase_ 
1.60 
99.40 
1+ 
6.40 
139 - 40 
• 4 + 
12.00 
231.40 
5 + 
7.60 
146.40 
5 + 
Auburn clay loam. 
.80 
32.20 
£+ 
•50 
72. 20 
Tr. 
i. 00 
164.20 
Tr. 
. 10 
79. 20 
Tr. 
Coming loam. 
2+ 
11+ 
Pleasanton. 
4.00 
64.40 
6+ 
2. 80 
104.40 
2+ 
3 J 
-30 
196.40 
Tr. 
20.00 
111.40 
17+ 
Montezuma clay loam. 
. 20 
32.20 
Tr. 
•30 
72. 20 
Tr. 
166.20 
79. 20 
Montezuma clay adobe 
2. 20 
86.80 
2+ 
8. 20 
126.80 
6+ 
25. 20 
218.80 
11+ 
16. 20 
133-80 
124- 
Yolo clay. 
3-70 
113-40 
3 + 
153-40 
5 + 
245.40 
160.40 
Tr. 
Yolo light type silt 
loam. 
4.00 
131.60 
3 + 
18.20 
171.60 
10+ 
19. 20 
263.60 
7 + 
23. 20 
178. 60 
124- 
Coming loam. 
58.80 
4+ 
98. 80 
— .06 
5 + 
Yolo gravelly loam.... 
2.18 
82.60 
2 + 
4-68 
122.60 
3+ 
33-68 
214.60 
iS+ 
23.68 
129. 60 
i 84 - 
Antioch loam. 
•50 
64.40 
Tr. 
•50 
104.40 
Tr. 
196.40 
.40 
ill.40 
Tr. 
Antioch light sandy 
loam. 
2.84 
105.00 
2+ 
14.04 
145-00 
9 + 
12.04 
237.00 
5 + 
21.04 
152.00 
13+ 
BAY AREA SOILS 
The figures for total nitrogen in the second column of Table III show 
that only 8 soils out of 30, or approximately 26 per cent, contain more 
than 0.1 per cent of nitrogen, and that only one of them contains more 
than 0.14 per cent of nitrogen. In other words, the foreign soils contain 
relatively 2% times as many soils which contain nitrogen in excess of 0.1 
per cent as do the soils of the Bay area; and, moreover, many of the 
first-named group contain very much more nitrogen than 0.15 per cent. 
The effects of the arid climate are therefore quite evident on soils of the 
Bay area and are only emphasized by comparison with the foreign soils 
existing under a humid climate. It must be further remarked that the 
comparison gains in significance from the reflection that while the Bay 
area soils are subjected to a long season of drought, they receive annually 
between 20 and 30 inches of rainfall, depending on the part of the area 
concerned, and are in addition protected from excessive oxidation influ¬ 
ences by much fog and cool weather. In respect to the number of soils 
