10 



BULLETIISr 441, U. S. DEPAETMENT OF AGRICULTURE. 



Table VIII. — Relative oxidation in plats treated with manganese sulphate and in the 

 corresponding check plats growing the same crops. 



Plats. 



Wheat. 



Rye. 



Timothy. 



Beans. 



Com. 



Cowpeas. 



Potatoes. 



Untreated 



100 

 2S3 



100 

 132 



100 

 75 



100 

 109 



100 

 76 



100 

 107 



100 



Treated with manganese 



105 



With the exception of the timothy and corn plats, the addition 

 of manganese sulphate has increased the oxidizing power of the soil. 

 In general, however, this increased oxidation agrees with the increased 

 yields in the limed soil. This is in contrast to the action of manga- 

 nese in this soil while under acid conditions, which caused less oxida- 

 tion in the soil and a decreased growth. Under acid conditions the 



Flu. 2.— Kye on a plat treated with manganese. 



effect of oxidizing compounds, such as manganese salts, is much 

 lessened or entirely inhibited, while under neutral or slightly alkaline 

 conditions this oxidizing power is stimulated. The soil under study 

 is of an acid character, naturally poor in its oxidizing power, and is 

 physically bad. Methods of cultivation which loosen and aerate 

 the soil and chemicals which increase its oxidizing power should 

 increase its crop-producing power. With the acid soil, where manga- 

 nese gave decreased yields, conditions were such that stimulating 

 action on plants and microorganisms of the soil did not come into 

 play; or, possibly on account of the acidity of the soil, the effect of 

 the manganese led to a stimulation of other biological processes, 



