424 
Journal of Agricultural Research 
Vol. VII, No. io 
As shown above, i per cent of dried blood failed to be nitrified in the 
virgin soil and that from the control plot, but underwent active nitrifica¬ 
tion in the previously manured soil as in the preceding series. The 
larger quantities of bone meal and ammonium sulphate also failed to be 
nitrified, but the lower concentrations of each of these substances under¬ 
went active nitrification in every case. Dried blood in a concentration 
of 0.625 P er cent, which corresponds closely with that used in the field, 
underwent active nitrification in all cases. The percentages of nitri¬ 
fication, calculated after subtracting the amounts of nitric nitrogen 
found in the control portions, show that when corresponding amounts 
of actual nitrogen from the different sources are compared the rates of 
nitrification of dried blood, bone meal, and ammonium sulphate were 
quite similar in all cases with the single exception of ammonium sulphate 
in the manured soil. In this case ammonium sulphate was oxidized 
the most completely of any of the materials studied. 1 
Soils from other localities have also been studied. Two samples were 
obtained from the lemon groves of a ranch in Ventura County. One of 
these (A) is a light sandy soil; the other (B), a heavy adobe soil high in 
organic matter. A sample was taken from a young lemon grove on 
another ranch in Ventura County and is a heavy clay soil, containing 
considerable organic matter. Another sample of a light sandy character 
was taken from an orange grove opposite the Tark Ellen station near 
Covina. A sandy loam containing considerable gravel and organic 
matter was obtained from a 24-year-old orange grove in the Ta Verne 
section in southern California. 
Studies were made in duplicate with the use of the same materials as in 
the preceding series. Since a 2 per cent concentration of dried blood (8, 
13,18) has been previously used to some extent in studies on nitrification, 
this proportion was added in certain cases. The concentrations of bone 
meal were varied from 4 to 0.5 per cent, and of ammonium sulphate, 
from 0.3 to 0.075 per cent. The results are given in Table III. 
Table III .—Nitrification in soils from different localities 
Materials added. 
Nitro¬ 
gen 
added 
per 
100 
gm. 
of soil. 
Sespe soil 
(A). 
Sespe soil 
(B). 
Limoneira 
soil. 
Lark Ellen 
soil. 
La Verne 
soil. 
Nitric 
nitro¬ 
gen 
found. 
Per¬ 
cent¬ 
age 
nitri¬ 
fied. 
Nitric 
nitro¬ 
gen 
found. 
Per¬ 
cent¬ 
age 
nitri¬ 
fied. 
Nitric 
nitro¬ 
gen 
found. 
Per¬ 
cent¬ 
age 
nitri¬ 
fied. 
Nitric 
nitro¬ 
gen 
found. 
Per¬ 
cent¬ 
age 
nitri¬ 
fied. 
Nitric 
nitro¬ 
gen 
found. 
Per¬ 
cent¬ 
age 
nitri¬ 
fied. 
Mgm. 
P.p.m 
P.p.m. 
P.p.m. 
P.p.m. 
P.p.m, 
None.. 
0 
61.0 
38.5 
49.0 
86.0 
34*o 
Dried blood: 
2.0 per cent. 
264.0 
6. 5 
0 
2 A* < 
O 
x.o per cent. 
132.0 
736.0 
51-1 
360.0 
24-3 
468.0 
3i- 7 
IO7.O 
i* 6 
442* 5 
30-9 
0.125 per cent. 
16. 5 
170.0 
66.1 
129.0 
54*9 
163.0 
69.1 
I9I- O 
63.6 
144.0 
66.6 
Bone meal: 
4.0 percent. 
170.0 
220.0 
9.4 
224.0 
10. 9 
332.0 
16. 6 
76. O 
0 
1.0 per cent. 
42. 5 
196.0 
34**6 
< v w 
222* O 
0.5 per cent. 
21. 25 
186.0 
58.8 
136.0 
45- 9 
152.0 
48. 5 
168.0 
38.6 
140.0 
49*8 
Ammonium sulphate: 
0.3 per cent. 
63.0 
328.0 
26. 5 
hi. 5 
XI. 6 
128.0 
12. 5 
162.0 
12. X 
0. 75 per cent. 
15- 75 
206.0 
'92.1 
106.0 
42.9 
148.0 
62. 9 
172.0 
54*6 
124.0 
57* 1 
Original soil. 
37-o 
25-5 
3i-5 
45*5 
23. 0 
1 It should be stated that the addition of calcium carbonate exerts almost no effect on the nitrification 
of dried blood in this soil. A preliminary report on the above phases of this investigation has previously 
been issued (15). 
