Understanding Micronutrients: Iron

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What does iron do in the plant?

Iron plays a vital role in chlorophyll production, catalyzing how light energy is absorbed to produce the plant’s food source. A heavy iron application in corn can give plants an almost black color as it enhances chlorophyll formation. This micronutrient is also crucial to plant respiration, carrying oxygen in the roots of legumes such as soybeans and peanuts. It also works to enhance other enzymatic processes within the plant.

What does iron deficiency look like?

Because of iron’s vital role in chlorophyll production, chlorosis is the critical marker for deficiency. Plants deficient in iron often show a pale green leaf color with yellow interveinal tissues. In corn, this can have a striping effect on the leaves. Because iron is immobile in the plant, a deficiency will show up in the new growth.

What conditions lead to iron deficiency?

Iron deficiencies tend to occur in soils with high pH. Iron is water-soluble and is quickly taken up by roots when soil pH ranges between 5.0 and 6.5. As soil pH increases, iron converts to an insoluble form unavailable for plant uptake. Soils with low organic matter levels are also more susceptible to iron deficiency.

In many cases, there is plenty of iron in the soil, but its availability to the plant is reduced due to soil conditions. These conditions can include low soil oxygen levels caused by compaction and water-logging or high temperatures. Metal imbalance can also be a factor in soil unavailability of iron, with high levels of copper, phosphorus, manganese, molybdenum or zinc.

How can you address micronutrient concerns around iron?

Soil sampling and analysis are essential for assessing your crop’s iron needs early. Because iron deficiency often isn’t the result of a lack of iron in the soil but an issue of balance and availability, soil testing can help you make the right decisions around your overall crop fertility plan.

Regular in-season tissue sampling is also an excellent tool for assessing your crop’s iron needs. Keeping a close watch on in-season nutrient deficiencies can help your crop perform consistently throughout all its growth stages. With micronutrients, by the time you see the outward signs of deficiency, your crop is likely already experiencing issues that can impact growth, reproduction and overall yield success, so consistent analysis is vital.

If the soil shows an imbalance that can affect a crop’s access to iron, a soil-applied micronutrient fertilizer can help you lay the foundation for success. As with any fertility decision, timing and placement are critical for responsible use. Always remember the 4Rs of Nutrient Stewardship — applying the right fertilizer source at the right rate, the right time and the right place.

Don’t let a preventable deficiency be your yield-limiting factor. Give your crops the right rate of iron at the right time and place to maximize crop potential with WOLF TRAX™ Dry Dispersible Powder™ (DDP) micronutrients. Iron DDP provides iron oxide and an iron amino acid complex, providing your crop's source for easy access and availability.

To learn more about iron and how to prevent iron deficiency, contact a Koch Agronomic Services (KAS) representative or visit the KAS Knowledge Center.

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