ACTION OF MANGANESE IN SOILS. 
15 
An experiment with this soil extract was started April 2 and run 
until April 16. The manganese chloride, sulphate, nitrate, and car- 
bonate were used in two concentrations, 20 and 50 parts per million. 
The results of this test are given in Table VI. 
Table VI. — Effect of manganese on growth and oxidation of wheat plants in extract of a 
poor lawn soil. ( Untreated extract = 100.) 
Treatment. 
Extract untreated 
Extract+MnCl 2 20 parts per million 
Extract-j-MnCl 2 50 parts per million 
Extract+MnS0 4 20 parts per million. . . 
Extract+MnS0 4 50 parts per million. . . 
Extract+Mn(N0 3 ) 2 20 parts per million 
Extract+Mn(N0 3 ) 2 50 parts per million 
Extract+MnC0 3 20 parts per million.. . 
Extract+MnC0 3 50 parts per million.. . 
Relative 
Relative 
growth. 
oxidation 
100 
100 
120 
136 
113 
150 
124 
130 
131 
166 
120 
114 
119 
115 
152 
175 
170 
200 
Manganese considerably increased oxidation and growth of the 
wheat in this soil solution, as shown by the table. The effect of each 
salt was quite marked and the beneficial action is greater with this 
soil than any previously reported. This experiment was repeated, 
but with only the manganese chloride and sulphate. The plants 
grew from April 16 to April 28. Manganese sulphate in amounts of 
20 parts per million increased oxidation 33 per cent and growth 21 per 
cent; with 50 parts per million oxidation was increased 50 per cent 
and growth 20 per cent. With manganese chloride in amounts of 20 
parts per million oxidation was increased 30 per cent and growth 22 
per cent; with 50 parts per million oxidation was increased 66 per 
cent and growth 21 per cent. In this experiment, as in the preceding, 
manganese in the solution greatly increased the oxidation and con- 
sequently made the solution a much better medium for the growth of 
plants. 
The experiments with these poor soil solutions indicate that the 
manganese, by increasing oxidation, has overcome their harmful 
properties. Treating the extracts of poor soils with carbon black is 
beneficial to growth and increases oxidation. Whatever increases 
root oxidation enables the plant to offset more or less the ill effects of 
injurious substances. Thus the harmfulness of dihydroxystearic acid 
is overcome by nitrate fertilizers and others which tend to increase 
root oxidation. 1 Dihydroxystearic acid interferes greatly with the 
normal root oxidation and nitrates stimulate this oxidation. The 
presence of other toxic organic substances in solution have been shown 
to be extremely deleterious to the oxidizing power of plants. This 
oxidizing power of the plants, especially in the presence of nitrates, 
i Schreiner, O., and Skinner, J. J., Some effects of a harmful organic soil compound. Bui. 70, Bureau of 
Soils, U.S Dept. Agr (1910), 
