ACTION OP MANGANESE IN SOILS. 



17 



The effect of manganese was also tested in the extract of Sassafras 

 sandy loam taken from a productive field. In this test the manga- 

 nese was used in concentrations of 20 parts per million. The chloride, 

 sulphate, nitrate, carbonate, and dioxide were used. The experiment 

 ran from November 12 to November 27. The results are given in 

 Table VIII. 



Table VIII. 



-Effect of manganese on growth and oxidation in productive Sassafras sandy 

 loam. ( Untreated = 100.) 



Treatment. 



Relative 



Relative 



growth. 



oxidation. 



100 



100 



79 



125 



90 



106 



88 



120 



95 



150 



105 



200 



Extract untreated.. 



Extract+MnCl 2 



Extract+MnS0 4 ... 

 Extract+Mn(N0 3 ) 2 

 Extract+MnC0 3 . . . 

 Extraet+Mn0 2 



The effect of the various manganese salts on this good soil was to 

 increase the oxidation by the plants; the growth, however, was even 

 decreased. The experiment was repeated with the same soil and 

 same manganese salts. The plants grew from December 1 to Decem- 

 ber 14. The results are given in Table IX. 



Table IX.- 



-Effect of manganese on growth and oxidation in productive Sassafras sandy 

 loam. ( Untreated =100.) 



Treatment. 



Relative 



Relative 



growth. 



oxidation. 



100 



100 



82 



106 



90 



100 



95 



116 



90 



140 



92 



150 



Extract untreated.. 



Extraet+MnCl 2 



Extract+MnS0 4 ... 

 Extract+Mn(N0 3 ) 2 

 Extract+MnCOs. . . 

 Extract+Mn0 2 



Again it is shown that manganese is not beneficial to this good soil. 

 In both experiments the oxidation by the plants was increased by 

 addition of the salts. Other experiments were made with this soil, 

 using varying amounts of several salts of manganese. The action, 

 however, was similar to those recorded above. There was no stimu- 

 lation of growth with any of the salts varying in amount from 5 to 

 100 parts per million. In each of the tests with this soil the plants 

 were affected, and after 10 days' growth the tips became yellow and the 

 leaves showed indications of drying up. These effects are the result 

 of excessive oxidation and probably show the cause of the harmfulness 

 of manganese in this and certain other good soils. The oxidizing power 

 of plants in these productive soils was already good, and they needed 

 nothing to stimulate this function. When manganese was added 

 the oxidation was increased and became even too great, thus causing 

 a harmful action. 



