THE EFFECT OF MANGANESE COMPOUNDS ON SOILS AND 
PLANTS 
E. P. Deatrick 
Experimental evidence has shown that phosphorus, sulfur, potassium, 
calcium, magnesium, iron, carbon, hydrogen, oxygen, and nitrogen are 
essential to the normal growth and development of plants. Other elements, 
including manganese, are almost universally found in soils and plants, 
and this fact has led some investigators to assume that they perform 
important physiological functions. The weight of evidence, however, 
seems to indicate that the benefit following applications of a manganese 
compound to soil is due to its stimulative, indirect action either on the 
plant or on the soil, and manganese is therefore usually designated as 
a catalytic fertilizer. 
The investigation here recorded was undertaken for the purpose of 
acquiring information regarding the specific effect of manganese com- 
pounds in increasing plant growth; in other words, to determine whether 
manganese is a direct plant stimulant, whether it increases the available 
food supply in the soil, or whether both these factors are operative. The 
direct stimulative or deleterious effect of a substance on plant growth 
may be determined by growing the plant to be studied in water cultures 
of a pure nutrient solution. When the same kind of plant is grown in 
soil to which the substance to be studied is added, the effect is usually 
very much modified. In the soil culture the action must be considered 
as the sum of the effects directly and indirectly on soil and plant. 
REVIEW OF LITERATURE 
Experiments with water cultures 
The effects of manganese on plants have been studied by growing 
seedlings in distilled water alone, and in distilled water to which nutrient 
salts were added. 
Working with the distilled water cultures, investigators have observed 
both stimulative and toxic effects. Loew and Sawa (1902-03)! found 
that in the presence of manganese in toxic quantities the leaves lose their 
1Dates in parenthesis refer to Literature cited, page 399. 
otl 
