Micronutrients can maximize crop performance
Andrea Rice, Director of Research, Education, and Outreach, Missouri Fertilizer Control Board
How is manganese used by the plant?
Manganese (Mn) plays a vital role in the enzyme systems in plants. It is responsible for activating several metabolic reactions and has a direct role to play in photosynthesis by aiding in chlorophyll synthesis. Correct manganese levels also increase availability of phosphorus (P) and calcium (Ca).
How can a manganese deficient field be identified?
Manganese is very immobile in plants, so deficiency symptoms appear first on younger leaves, with yellowing between the veins. Sometimes a series of brownish-black specks appear. Deficiencies are most common in high organic matter soils and in those soils with naturally low Mn content and neutral to alkaline pH.
Manganese deficiencies typically occur in soils with a high pH, but can also result from other nutrients such as calcium (Ca), magnesium (Mg), and iron (Fe) being imbalanced.
Manganese deficient soybeans. Image credit: Michigan State University Extension
How should manganese be applied?
Manganese can be applied by broadcasting it along with other fertilizer to increase soil test levels, but many situations will require foliar applications. Due to an increase of Mn deficiency in sandy soils, there is also an increase in leaching potential. Foliar application will decrease chances of leaching and maximize plant utilization.
Manganese sulfate is the most efficient form of manganese fertilizer. In foliar application, the sulfate form or chelated manganese should be used. Manganese oxide may be appealing because it is a cheaper form of Mn fertilizer, but it contains less available manganese and is less cost-effective.
Manganese deficient wheat. Image credit: Washington State University Extension
Is manganese more useful in specific areas of crop production?
Soybeans and wheat require more Mn than many crops.