Tue Errect oF MANGANESE CoMPOUNDS ON SOILS AND PLANTS 377 
According to Schreiner, Sullivan, and Reid (1910:37), “ soils may have 
practically the same amount of manganese and still vary greatly in oxidiz- 
ing power, so oxidation in soils, if due to manganese, depends on the nature 
of the manganese as much as on the amount.” The salts of manganese 
added to soils which were low in this element and had “ very little oxidiz- 
ing power,” did not increase their power to oxidize aloin. Experiments to 
learn the effect on oxidation of the addition of hydroxy acids and salts to 
manganese compounds in the soil, led these authors to state (page 56 of 
reference cited): ‘This oxidation appears to be mainly nonenzymotic, 
the result of interaction between inorganic constituents and certain types 
of organic matter. It may also be brought about by organic matter in 
a state of autoxidation and by inorganic oxygen carriers, such as man- 
ganese and iron. Both processes activate oxygen.” 
- According to Sullivan and Reid (1912:28), ‘‘ That the catalytic power 
of the soil is correlated to some degree with the manganese content of 
the soil is evident.”” A comparison of soils of varying manganese content, 
and the failure of the addition of manganese salts to increase the catalytic 
power of soils that were poor catalyzers even tho the content of manganese 
was high, led these investigators to state that factors other than the “ total 
amount of manganese must be the determinants.” They suggest that 
either the nature of the manganese compound or the nature of the associ- 
ated organic matter is more important than the amount of manganese. 
Experiments with soil fungi and bacteria 
Altho the experimentation is meager, the weight of evidence supports 
the conclusions of Bertrand (1909) that manganese stimulates the growth 
of fungi. Loew and Sawa (1902-03), however, found no stimulation, and 
they have written at length on the difference of the behavior of manganese 
on the growth of phanerogams. 
Kelley (1912) concluded that nitr Geation took place more rapidly in the 
soil high in manganese, while ammonification was about equal in soils 
ef either high or low manganese content. Leoncini (1910) and Montanari 
(1914) have found that manganese increases the activity of nitrifying 
bacteria. 
Brown (Brown and Minges, 1916) applied various salts of manganese 
to soil cultures, and concluded from his data that ‘‘if manganese salts 
in small quantities increase crop yields on a soil, that increase may be 
