Manganese byproducts produced in the course of manufacturing electrolytic manganese dioxide provide a novel manganese fertilizer having a fertilizer response that can operate both instantaneously and slow-release. A manganese fertilizer contains manganese byproducts and has 3 to 20 wt % citric acid-soluble manganese (C-MnO) and 0.5 to 7.0 wt % water-soluble manganese (W-MnO).
