THE ACTION OF CERTAIN NUTRIENT AND NON-NUTRIENT 

 BASES ON PLANT GROWTH — II 



THE TOXICITY OF MANGANESE AND THE ANTIDOTAL RELATIONS 

 BETWEEN THIS AND VARIOUS OTHER CATIONS WITH RESPECT TO 

 GREEN PLANTS * 



M. M. McCooL 



{Received for publication July 1, 1912) 



Manganese is widely distributed in nature. It occurs in various soil 

 types, in some instances in sufficient amount to be injurious to certain 

 crops. It is likewise present in a variety of plants. The role of man- 

 ganese in plant nutrition is not clearly understood, but the metal is con- 

 sidered to be of importance in connection with the oxidizing enzymes. 

 The salts of manganese have been shown to have a stimulating action on 

 plants when applied to soils in small quantities ; but in larger quantities the 

 effect is of course detrimental. 



The studies that are included in this report consider two chief relations: 

 (1) the toxicity of manganese in distilled water, in full nutrient solution, 

 and in soil cultures; and (2) the antidotal relations that exist between 

 manganese and each of the bases calcium, potassium, sodium, and mag- 

 nesium. 



OCCURRENCE OF MANGANESE IN SOILS 



As stated above, m.anganese occurs in various soil tjqoes. Fertile soils 

 as a rule contain less than one per cent of this element reckoned as oxid. 

 The following table from Wolff (1870-1880) is cited in order to indicate in 

 general the amounts of manganese and iron found in soils: 



Kind of soil 



Percentage 

 of Mn304 



Percentage 

 of Fe203 



Loam 



.135 

 .180 

 .080 

 .042 



2 096 



Clay 



3 173 



Sand 



1 039 



Humus 



406 







* Laboratorj' of Plant Physiolog>-, Cornell Univer.sity, Contribution No. 10. 



171 



