When it comes to plant requirements, iron is needed in small amounts to facilitate proper plant growth and production.

Often it’s not a lack of iron in soils, but the plant-available level in soils or reduction to unavailable forms within the plant that results in yellowing, stunted growth, and even death (known as iron chlorosis).

Row crops sensitive to low iron levels include corn, beans, sorghum and potatoes. Wheat and alfalfa are the least sensitive.

How It Behaves

Iron helps plants stay healthy and green by aiding in key processes such as chlorophyll synthesis, photosynthesis, enzyme activation and energy transfer.

“The chlorophyll/photosynthesis role is one reason why iron deficiency will show as yellowing of leaves in susceptible plants, and deficiency can result in less plant growth and yield,” says John Sawyer, a soil fertility specialist at Iowa State University Extension.

The main uptake of iron occurs through the root tips. Young seedlings express the most severe symptoms.

“Typical symptoms of iron deficiency in soybeans are interveinal chlorosis of new leaves, with leaf tissue pale green, yellowish, to nearly white coloration,” Sawyer says. “The interveinal tissue can die and fall out, leaving tattered-looking leaves.

“Different crops have varying susceptibility to iron chlorosis, with soybeans being the most common. Even varieties within soybeans have different susceptibility.”

Iron intake can be disrupted by the presence of other nutrients, depending on the ratio in the root zone. Excessive amounts of soluble phosphorus, nitrogen, zinc and molybdenum, or low rates of potassium, may hinder iron…