ACTION OF MANGANESE IN SOILS. 
13 
Table III. — Effect of manganese (50 parts per million) on growth and oxidation in 
extracts of a poor sandy loam soil. ( Untreated extract taken as 100.) 
Treatment. 
Relative 
growth. 
Relative 
oxidation. 
100 
114 
116 
108 
111 
100 
Extract+MnCl 2 
116 
Extract+MnSO< 
140 
Extract+Mn(N0 3 ) 2 
200 
Extract+MnC0 3 
196 
There was an increased oxidation power of the plant roots in the 
manganese cultures. Each of the salts caused an increase in oxida- 
tion and also an increase in the growth. The manganese chloride 
increased oxidation 16 per cent and growth 14 per cent. The sulphate 
increased oxidation 40 per cent and growth 16 per cent. The nitrate 
increased oxidation 100 per cent and growth 8 per cent. The car- 
bonate increased oxidation 96 per cent and growth 11 per cent. It 
should here be noted in connection with the last two compounds that 
root oxidation is also greatly increased by nitrates and by alkaline 
conditions, as shown by Schreiner and Reed. 1 The high oxidation 
here noted is therefore the summation of the effects of manganese and 
nitrate or carbonate, respectively. 
The greatest amount of oxidation in the solutions containing the 
different salts of manganese does not give the largest increase in 
growth. This suggests that the oxidation in the solutions contain- 
ing the nitrate and carbonate in the amounts of 50 parts per million 
was perhaps too great for the best growth in this culture medium. 
Another experiment with this soil extract was made using several 
concentrations of manganese sulphate, namely, 10, 30, and 50 parts 
per million. Two cultures were run in each treatment. The experi- 
ment continued from February 9 to February 19. The results are 
given in Table IV. 
Table IV. — Effect of manganese sulphate on oxidation and growth of wheat in extracts 
of a poor sandy loam. ( Untreated taken as 100.) 
Treatment. 
Extract untreated 
Extract + manganese 10 parts per million 
Extract + manganese 30 parts per million 
Extract + manganese 50 parts per million 
Relative 
oxidation. 
100 
133 
173 
210 
As seen in the table, the oxidation and growth increased as the 
amount of manganese in the solution increased. This experiment 
was repeated, the plants growing from February 25 to March 13. 
The results were very similar to those in the first test. With 10 parts 
per million, manganese oxidation was increased 35 per cent and 
Bui. 56, Bureau of Soils, U. S. Dept. Agr. 
