THE AVAILABILITY OF VARIOUS MANGANESE OXIDES TO PLANTS

A number of oxides of manganese were prepared and their crystalline structures were indentified by X-rays. They were added to four soils on which plants suffered from manganese deficiency. Oxides of the structures manganite, manganous manganite, and pyrolusite cured manganese deficiency of oats and peas. All the successful oxides consisted of very small particles, as shown by electron micrographs. The amount of the oxides dissolved by aqueous quinol during an hour at room temperature was correlated with their ability to supply plants with manganese.