Metal ions selected from the group consisting of Fe.sup.+3, Mn.sup.+2, Cu.sup.+2 and Zn.sup.+2 are administered to plant roots in a composition comprising citric acid, whereas the molar ratio of citric acid to metal ions in this composition is about 0.8 to 2.5.

A plant nutrient composition and a method of its administration is disclosed, providing plants with one or more metal ions in a form in which said metal ions can be absorbed by plants. The composition comprises a product obtained by mixing said one or more metal ions with a reducing sugar following heating of the sugar under alkaline conditions.

An aqueous manganese micronutrient solution comprising between 0.1 and 2.0 wt. % of ferrous ion, about 5 wt. % manganous ion, between 1 and 1.5 moles of citric acid anion per mole of manganous ion and ammonia in an amount to maintain the pH of the solution between 7.5 and 12.

Methods for rendering high concentrations of manganese safe for plant growth, comprising the steps of, mixing one or more alkyl glycosides with Mn resulting in a mixture comprising Mn at a concentration of between about 20 to 75 ppm, and applying a suitable volume of the resulting mixture to one or more plants; and formulations for same.