Micro-Nutrient Feature: Manganese

Micronutrients are just as important for plant growth as the primary and secondary nutrients, but are required in smaller quantities and the amount required varies by crop.  All plants need 8 micro-nutrients to grow: Iron, Copper, Chloride, Boron, Manganese, Molybdenum, Nickel, Zinc. Of these essential micronutrients, manganese is particularly important for soybeans and wheat.

Manganese is important for photosynthesis, chlorophyll production and is essential for phosphorus and magnesium uptake into the plant.  It plays a significant role in disease prevention also. You can often reduce the incidence of sclerotinia white mold by having good levels of Manganese. Soybeans, wheat, and edible beans are particularly responsive to manganese.  

Manganese Deficiency photo source: University of Minnesota

If you know that your soils are low in Manganese it is a good practice to foliar apply Manganese fertilizer in-season.  Plants deficient in Manganese will have yellowing between the veins of the youngest (top) leaves, while the veins will remain dark green.  Once leaf yellowing is observed yield loss has already occurred, and although a foliar application will help the plants green-up, it will not bring back the lost yield. In low Manganese fields plan for a foliar application early (about canopy closure timing in soybeans) to be proactive against yield loss. 

Factors that Reduce Manganese Availability:

• Low soil manganese (less than 35 ppm)

• Dry weather (drought)

• Poorly drained soils

• High soil pH

• Sandy soils

Resources: Ontario Publication 611 - Soil Fertility Handbook;

A&L Micronutrients Factsheet