ACTION OF MANGANESE IN SOILS. 



Table II. — Effect of manganese on growth of plants in a -productive loam soil. 

 ( Untreated equals 100.) 



Manganese 













(parts per 



MnCl 2 . 



MnSO*. 



Mn(N0 3 ) 2 . 



MnC0 8 . 



Mn0 2 . 



million) . 

















100 



100 



100 



100 



100 



10 



103 



99 



104 



101 



103 



25 



100 



102 



105 



100 



99 



50 



101 



100 



100 



103 



100 



100 



102 



98 



97 



98 



102 



250 



97 



98 



98 



100 



99 



By an examination of the table it is seen that there is no apprecia- 

 ble increase with any of the manganese salts. There is a slight in- 

 crease in some cases and frequently a slight depression. The slight 

 differences may be due to experimental errors ; at least it seems fair 

 to conclude that manganese has no beneficial effect on this loam soil, 

 which is already productive. 



Investigators have invariably found that the action of manganese 

 was different on different soils. The beneficial effects secured in 

 most of the experiments were when the manganese was applied to 

 a deteriorated soil. This was especially so in the work of Katayama x 

 and Kakehi and Baba, 2 who secured large increases. On the other 

 hand, Gregoire, Hendrick, and Carpiaux, 3 among others who worked 

 with manganese on a rich soil, noticed no beneficial action. 



MANGANESE IN AQUEOUS EXTRACTS OF SOILS. 



Further studies were made on manganese salts in the aqueous 

 extracts of good and poor soils. The effect on growth was noted 

 and the oxidizing power of the plant roots in the solution as influ- 

 enced by manganese salts received especial attention. 



Some interesting work has been done with the action of manganese 

 in aqueous solutions. Aso 4 found that manganese stimulated growth 

 of radish, barley, wheat, and peas in nutrient solution when added 

 in amounts of 20 parts per million. He showed that the plants grown 

 in solution containing manganese yielded a juice which has a more 

 powerful oxidizing power than the plants without manganese. A 

 yellowing of the leaves of the manganese plants occurred and the 

 roots turned dark. Bertrand 5 had observed that the ash of oxidizing 

 enzymes contain manganese and that in the presence of manganese 

 the oxidizing effect of these enzymes is greatly increased. 



» Bui. Col. Agr. Tokyo, 7, 91 (1906-1908). 

 « Bui. Col. Agr. Tokyo, 7, 455 (1906-1908). 

 »Bul. Agr. (Brussels), 23, 388 and 764 (1907). 



4 Aso, K., On the physiological influence of manganese compounds on plants. 

 6, 177 (1902-3). 

 oCompt.rend., 124, 1032 (1897). 



25873°— 14 2 



Bui. Col. Agr., Tokyo, 



