Oct. 9, 1916 
Nitrifying Powers of Humid and Arid Soils 
7i 
TablB VII .—Percentage of California soils transforming more than 10 per cent of 
nitrogen present in culture into nitrate 
Form of nitrogen. 
Soil area. 
Riverside. 
Pasadena. 
Bay. 
Ukiah. 
Soil nitrogen alone.,.. 
47 
34 
0 
0 
Soil nitrogen plus ammonium sulphate . 
47 
47 
6 
10 
Soil nitrogen plus dried blood. 
30 
28 
10 
14 
Soil nitrogen plus cottonseed meal. 
70 
50 
20 
iO 
It appears, therefore, that in the Riverside, Pasadena, and Bay areas 
the cottonseed-meal nitrogen gives the best results in the largest number 
of soils. In the Ukiah area cottonseed meal takes second place and 
divides honors with sulphate of ammonia. Sulphate of ammonia takes 
second place in the Riverside, Pasadena, and Ukiah area soils, but third 
in the Bay area soils. The soil nitrogen does, however, contend with it 
for second place in the Riverside soils. Dried blood is last in both the 
Pasadena and Riverside soils, but first in the Ukiah soils and second in the 
Bay area soils. Soil nitrogen is either second or third in the Riverside 
soils, is third in the Pasadena soils, and last in the other two areas. 
Table VIII gives relative values on another basis than that employed 
in Table VII. This latter criterion consists in computing the percentages 
of soils which produce with every form of nitrogen more than 15 mgm. 
of nitrate in the foreign soils and is based on the amounts of total nitro¬ 
gen present in corresponding quantities in the other soil areas. Thus, 
the figure is 11 instead of 15 for the Ukiah area, 10 for the Bay and 
Pasadena areas, and 5 for the Riverside area. 
TablU VIII .—Percentages of soils producing more than 15 mgm. of nitrate in foreign 
soils with every form of nitrogen 
Form of nitrogen. 
Soil area. 
Riverside. 
Pasadena. 
Bay. 
Ukiah. 
Foreign. 
Soil nitrogen alone. 
Soil nitrogen plus ammo¬ 
24 
18 
0 
0 
52 
nium sulphate. 
Soil nitrogen plus dried • 
71 
71 
16 
25 
25 
blood.. 
Soil nitrogen plus cottonseed 
41 
42 
30 
31 
81 
meal. 
75 
80 
23 
21 
63 
Similar relations appear to hold in this manner of computation as in 
that previously employed. Some minor differences, however, are appar¬ 
ent. Ammonium sulphate very definitely takes second place in all the 
California soils except the Bay area. Cottonseed meal is still first in 
the Riverside and the Pasadena soils, but blood is first in the Ukiah and 
Bay area soils. The soil nitrogen is fourth in all the California soil areas. 
