Dec. 4,1916 
Nitrification in Semiarid Soils 
427 
Tabi,E V.— Effect of alkali salts on the nitrification of dried blood and ammonium sulphate 
Nitric nitrogen (per million). 
Alkali salt added. 
Control plot. 
Manured plot. 
0.1 per 
cent of 
dried 
blood. 
0.0625 per 
cent of 
ammonium 
sulphate. 
0.15 per 
cent of 
ammonium 
sulphate. 
1.0 per 
cent of 
dried 
blood. 
0.1 per 
cent of 
dried 
blood. 
0.15 per 
cent of 
ammonium 
sulphate. 
None. 
108. 0 
98. O 
89. 0 
172. 0 
106. O 
170.0 
Sodium carbonate: 
0.05 per cent. 
0.1 per cent.. 
104. 0 
160. 0 
s6. 0 
33 * 5 
31.0 
19. O 
108. O 
102. 0 
129. O 
62. O 
0.5 per cent. 
i* 5 
1.9 
1. 1 
7.6 
a no. 0 
5 * 6 
Sodium sulphate: 
0.1 per cent. 
115.0 
96. O 
60. 0 
296. O 
103.0 
174.0 
0.5 per cent. 
98. 0 
95 *o 
41. 0 
48. 0 
102. 0 
134.0 
a 0.4 per cent of sodium carbonate was used in this case. 
Considering the results from the control plot, it is interesting to note 
that 0.1 per cent of sodium carbonate produced no effect upon the 
nitrification of a concentration of 0.1 per cent of dried blood, was dis¬ 
tinctly toxic to the nitrification of a concentration of 0.15 per cent of 
ammonium sulphate, and markedly stimulating to the nitrification of 
a concentration of 0.0625 per cent of ammonium sulphate. A concen¬ 
tration of 0.5 per cent of sodium carbonate was toxic in all cases. 1 
With a 1 per cent concentration of dried blood in the soil from the 
manured plot, the addition of a concentration of 0.05 per cent of sodium 
carbonate was quite toxic to nitrification, causing a reduction in the 
yield of the nitrate from 172 to 31 p. p. m. A 0.1 per cent concentration 
of sodium carbonate was still more toxic, while a concentration of 0.5 
per cent totally inhibited nitrification. (The original soil contained 
6.7 p. p. m.) With the use of 0.1 per cent dried blood no effects were 
produced by any of the concentrations of sodium carbonate employed. 
With the use of a concentration of 0.15 per cent of ammonium sulphate 
the addition of 0.05 or 0.1 percent sodium carbonate retarded nitrifica¬ 
tion considerably, especially in the case of the latter, but not so markedly 
as was found in the case of 1 per cent dried blood. 
The addition of a concentration of 0.1 per cent of sodium sulphate was 
without effect on the nitrification of 0.1 per cent dried blood or an equiv¬ 
alent amount of ammonium sulphate in the control plot, and upon the 
nitrification of concentrations of 0.1 per cent of dried blood or 0.15 per 
cent of ammonium sulphate in the manured plot; but it produced marked 
stimulation with 1 per cent dried blood in the manured plot and was 
toxic with 0.15 per cent ammonium sulphate in the control plot. A con¬ 
centration of 0.5 per cent of sodium sulphate was somewhat toxic with 1 
1 The chemistry of the action of sodium carbonate and other sodium salts on this soil will be discussed in 
a subsequent paper. Suffice it to say that considerable light has been thrown on the above results from 
a study of the pure chemistry involved. 
