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. 



Relative 



Relative 



growth. 



oxidation 



100 



100 



120 



136 



113 



150 



124 



130 



131 



166 



120 



114 



119 



115 



152 



175 



170 



200 



Extract untreated 



Extract+MnCl2 20 parts per million 



Extract+MnCl 2 50 parts per million 



Extract+MnS04 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 

 Extraet-i-MnC03 20 parts per million. . . 

 Extract+MnC0 3 50 parts per million. . . 



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). 



