Manganese is a micronutrient that punches above its weight in maintaining the health and vigor of various crops. A manganese deficiency can affect overall crop performance nearly as much as a deficiency of the Big 3 macronutrients: nitrogen, phosphorus and potassium

Crops with high manganese requirement include soybeans, wheat, barley and oats. Corn has a medium manganese requirement. 

Koch Industries writes manganese is vital to the reactions responsible for photosynthesis, is an activator for enzymes in the growth process and supports conversion of nitrate, which is readily used by crops. In addition, manganese assists iron in chlorophyll formation. Other research indicates manganese plays a part in the root zone to assure lignin formation on the roots to help prevent soil-borne pathogen damage there. Also, the element is active in combating environmental stress in plants, such as drought, extreme temperatures, and insect and disease damage.

Cornell University agronomists say while manganese is usually available in adequate amounts for cash crop production, certain soil conditions — such as recently limed fields, soils with pH readings above 6.0 and heavy, high-organic matter muck soils — can tie up manganese chemically, leading to deficiencies.

Deficiency Environments

In high pH soils, manganese can precipitate, lowering its plant availability in over-limed fields or those of weathered calcareous parent material. Manganese is most available at soil pH levels of 5-6.5. Below 5.0 pH, manganese may become too available, leading to toxic accumulation within the plant.

Organic muck soils are more likely to show manganese deficiencies as the…