12 BULLETIN 441, U. S. DEPARTMENT OF AGEICULTUEE, 



. The action of manganese was studied on the same plats, kept 

 neutrahzed with lime for the three succeeding years following the 

 experiment with the soil in an acid condition. 



The productivity of the soil was increased by manganese under 

 this neutral or slightly alkaline condition. With wheat, rye, timothy, 

 beans, corn, and cowpeas the yields were increased, while with 

 potatoes the yield was practically the same in the treated and the 

 check plats. 



The oxidative power of the neutralized soil was also increased by 

 manganese, which is in accord with the results of former investiga- 

 tions, which have shown that the oxidation by manganese salts is 

 greater under shghtly alkaline conditions. 



The action of manganese in decreasing the oxidation in the soil 

 while acid is in harmony with the decreased yield, and its action in 

 increasing the oxidation of the neutralized soil is in harmony with 

 the increased yield. The action of manganese in the acid soil was 

 probably to stimulate the life processes in the soil, acting on the 

 organic matter in such a way as to produce changes which resulted 

 in a lessened crop-producing power, while its action in the neutralized 

 soil was such as to stimulate oxidation and other biological processes, 

 acting on the organic soil constituents and producing changes 

 favorable to the growing plants. 



These results on the behavior of manganese as a so-called catalytic 

 fertilizer when acting under acid or neutral soil conditions show that 

 no profitable return is to be expected in soils of a persistent acid 

 tendency until such soils are limed. 



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