What micronutrient strategy is most effective?

May 11, 2021
Devin Wirth, a CHS agronomy technical specialist, discusses the benefits of timely, efficient micronutrient applications to promote plant health and optimize yield potential. 

Is your crop getting the full benefit of micronutrient applications? Although used in small amounts, micronutrients play an outsized role in plant health. Application timing and rate will determine how beneficial micronutrients will be, leading to some debate over the most effective strategies.

Crop responses to micronutrient applications are complex, says Devin Wirth, agronomy technical specialist with CHS. They are affected by many factors, including soil fertility, growing conditions and the characteristics of each micronutrient.

“Micronutrient impact is typically most observed in crops that are either deficient in a certain micronutrient or being pushed for higher yields and need more nutrition to keep up with increased demand,” he says. “Adding to the complexity, some micronutrients are taken up better by the roots, so it makes sense to apply them during spring planting. However, applying micronutrients to soil runs the risk of reducing nutrient availability, rendering them useless for plant uptake.”

Untangling micronutrient efficacy

Mixing a chelate into the micronutrient application is one solution to improving nutrient availability.

“Chelates surround the micronutrients we apply and bond with them so dynamic soil factors can’t affect the nutrients,” says Wirth. One example is an ortho-ortho EDDHA chelate, commonly used to protect and increase uptake of micronutrients in the soil.

Chelates may not be needed with an in-season post application, since micronutrients are applied in their most-available form so foliar uptake is optimized, says Wirth.

Preventive vs. corrective micronutrient applications

While some growers want the insurance policy a preventive micronutrient application can provide, others opt to wait to apply micronutrients until deficiencies are shown in the plant or with a tissue test. While both methods have merit, Wirth says preventive micronutrient applications helps maintain plant health to reduce yield loss from deficiency and nutrient tie-up. He likens preventive micronutrient applications to applying a fungicide.

“By applying a fungicide preventively, you help ensure a disease doesn’t enter the plant and immediately start reducing your yield potential,” he notes. “It’s the same principle when you apply micronutrients before a limiting deficiency occurs. Many farmers know from year to year what their nutrient deficiencies are or rely on regular tissue tests. If not, they’ll see the signs show up later in the season. However, by the time tissue tests identify a micronutrient deficiency, the damage is done. A preventive approach gives you many more benefits.”

close up of young corn