Answers are from the Indiana certified crop adviser panel: Gene Flaningam, Flaningam Ag Consulting, Vincennes; Carl Joern, Pioneer, Lafayette; and Greg Kneubuhler, G&K Concepts, Fort Wayne.

 

My daughter learned in her agronomy class that I can help my soybeans pull up more nutrients by topdressing trace elements link zinc and copper at R1. Is that worth it? And is R1 the best time to make that application?

 

Flaningam: Zinc and copper on soybeans may be necessary if you are striving for high yields. We seem to apply most of our trace elements to our corn crop and forget about trace element needs of the soybean crop. Zinc doesn’t move in the soil very well and has limited availability in dry soil conditions. Applications need to be placed into the root zone. Copper can enhance the chlorophyl process in seed production and can also help reduce sudden death syndrome in soybeans. If you apply at R1, a foliar-grade trace element may be more practical than topdressing with a dry fertilizer.

 

Joern: Independent research has shown that high-yielding soybeans are often associated with higher concentrations of micronutrients such as zinc, manganese and copper. Notably, these nutrients tend to appear in higher concentrations in tissue samples taken later in the reproductive stages compared to R1. This suggests that applications of these trace elements should be made before peak uptake to ensure the plant accumulates enough to avoid yield limitations.

 

However, Science for Success, a land-grant research collaboration on soybeans, found that prophylactic foliar feeding did not consistently produce a positive return on investment across all trials. This reinforces the idea that intensive micronutrient management should be based on plant need rather than applied as a standard practice.

 

Consider pulling tissue samples to determine whether your field is deficient in these trace elements. If the plants aren’t showing a need, would you expect a meaningful yield response from a supplemental application?

 

Kneubuhler: The micronutrients soils tend to be short on are manganese, zinc and boron. Most soils are not sufficient in these elements, and we don’t put them back in most cases. Copper is also important for chlorophyll production and seed development. Generally, these minor elements are most economically treated with a foliar application in the reproductive stages. It takes large amounts of broadcast to get a crop response if we try and build soil levels. That can be quite cost prohibitive.

 

Not all soils will create micronutrient deficiencies, but many in Indiana do. A series of tissue samples can reveal the need and potential response to foliar micronutrients like zinc, copper, manganese, boron and others. But I highly recommend following a tissue sampling schedule. Otherwise, you can misinterpret the true needs of plants.