The reaction can be reversed by the addition of a reducing agent. Dehydration will cause the following split of the dehydrated oxide:

(MnO)x(MnO₂)y.(H₂O)z>xMnO+y MnO₂+,H₂O.

The reaction is considered to be reversible. Thus the treatment of manganese deficiency can be approached by using these fundamental reactions.

First, the deficient condition can be corrected by direct applications of manganous salts. If the soil has a high capacity for the fixation of manganese, their efficiency will be low.

Secondly, the fixation capacity of the soil can be reduced by applying acid-forming material, which reduces the hydroxyl concentration. The formation of the hydroxide is the first step in the fixation, and subsequent oxidation of the manganese to the hardly soluble hydrated oxide can be reduced by decreasing the hydroxyl concentration of the soil through its acidification.

Lastly, manganese deficiency can be corrected by the application of reducing agents. The application of hydroquinone, stannous chloride, hydrazine sulfate, and sodium azide have corrected manganese-deficient soil by increasing the available manganese.

Likewise the correction of manganese toxicity can be accomplished by taking advantage of the manganese cycle in soils. The soluble and available manganese can be reduced by increasing the hydroxyl concentration in soil by the application of lime and by using mulches to prevent dehydration through exposure to wind and sun.

SEVERAL METHODS for the correction of manganese-deficient soils have been discovered and are recommended for use by farmers, gardeners, and greenhouse operators. The methods recommended include the direct application of manganese and indirect methods, which are based on the reversion of the manganous-manganic equilibrium.

The common method of correcting manganese deficiency is to apply manganese salts to the soil. The rate of application is determined by the type of soil and by its fixation capacity.

Applying 50 to 100 pounds per acre of manganese sulfate to mineral soils, in which the manganese deficiency has been caused by overliming, generally will give adequate results. On soils having a slightly acid to neutral reaction, 50 to 100 pounds of manganese sulfate may be applied; 100 to 200 pounds may be put on those having a neutral to slightly alkaline reaction, and 200 to 400 pounds on soils having a strongly alkaline reaction.

At 1957 prices, manganese sulfate was the most economical means of applying soluble manganese. The use of insoluble manganese compounds, such as pyrolusite, was not considered economical because heavy applications of those compounds, finely ground, are needed to produce the same effect as smaller amounts of manganese sulfate.

An early method of correcting unproductive manganese-deficient soil was to change its reaction with the application of sulfur and other acid-forming materials. The method was economical and gave good results on organic soils. Sulfur should be used only on soils where it will bring about a relatively permanent change in reaction. Some organic and sandy soils can be economically treated in this way; among them are peat soils; soils in Michigan, Indiana, and New York; and the soils of the Coastal Plains.

To apply manganese directly to a soil with a high-fixation capacity is an inefficient way to correct a manganese-deficient condition. Two other methods are more efficient and economical. The first is to apply manganese sulfate and sulfur together. The sulfur increases the availability of the manganese by retarding its oxidation through the reduction of the hydroxyl ion concentration. Plants growing on a manganese-deficient soil that got 400 pounds of manganese sulfate and 500 pounds of sulfur had 2.5 times more manganese in their tissues than plants growing in similar soil that got 400 pounds of manganese sulfate alone.

The other method is to apply manganese sulfate as a spray to the foliage. This method was used at the Rhode Island Agricultural Experiment Station in 1925. Many citrus growers have used it. It is economical wherever it is possible to spray the plant. The sprays have been successful on general crops, such as potatoes and cereal crops.

Manganese deficiency in a soil may be corrected temporarily by steam or sterilization by dry heat. This treatment causes a great increase in soluble manganese in the soil. The explanation for this phenomenon lies in the dehydration of the hydrated oxides, especially MnO.MnO₂. The aftereffects of steam sterilization can be explained by its effect on the solubility of manganese. When a soil containing large amounts of oxides of manganese is sterilized by this means, a manganese toxicity condition is produced in respect to plant growth. This effect will disappear eventually.

The improvement of soils that have a content of soluble manganese toxic to plant growth requires a treatment that will cause the oxidation of the soluble manganese. This is done by using lime and mulch to protect hydrated oxides from dehydration.