BLOOMINGTON, Ill. – Farmers looking to save money during times of lower commodity prices may want to skip foliar fertilizers. 

That was the message in a discussion by by Dr. Rachel Vann, Extension soybean specialist with the University of North Carolina, during a recent “Field Talk” event hosted by the Illinois Soybean Association (ISA).

Farmers and agronomists with Science for Success, a multi-state collaboration of 25 university Extension specialists supported by the soybean checkoff program and United Soybean Board, have been working hand in hand to test different fertilizer products to improve yield. The efficacy of foliar fertilizer products in boosting soybean yield is one area of interest to farmers the team has been studying.

“We examined the most frequently used foliar fertilizers at the time of our study. What we found was that these foliar fertilizer products did not increase yield in all these diverse environments across the United States,” Vann said. “Knowing this could save growers $13 per acre if you look at these products’ prices. (Multiplied) over 500 acres of soybeans that savings could pay for a semester of college for your child or grandchild.”

“We conducted a national trial on many different soil types across the U.S., and I think that allows us in certain circumstances to make better recommendations,” said Vann, a Geneseo, Ill., native and Science for Success team leader. She explained farmers are interested in foliar fertilizers that usually combine a mixture of micronutrients and macronutrients and can be tank-mixed with insecticides and fungicides. These fertilizers are applied during early reproductive growth (R1-R4), corresponding with a period of high nutrient uptake for soybeans.

“Foliar nutrients enter the plant without touching the soil, which could be helpful under certain conditions,” Vann said. “Generally they are mixed with water and applied with a sprayer, usually at low application rates.”

The Science for Success team conducted small-plot field trials at a total of 46 sites in 16 states. Six foliar nutrient products were applied to plants at the R-3 growth stage – trademark brands FertiRain, Sure-K, Harvest More Urea Mate, BRANDT Smart B-Mo, BRANDT Smart Quatro Plus and MAXIMUM N-Pact K. Another small plot was left untreated. Yield data were collected via combine and adjusted to 13 percent moisture, as were grain protein and oil concentrations after measuring.

Vann concluded by advising growers that in times of low commodity prices, such as now, the Science for Success team could not endorse the use of foliar fertilizers on soybeans unless plants exhibit visual nutrient deficiency symptoms. The team published an Extension paper with full details on their foliar fertilizers trial that is available at https://doi.org/10.1002/agj2.20889.

In addition to their work on foliar fertilizer and yield, the team is researching the biological seed treatment market. Some bio seed products claim that they help with nitrogen fixation, increase phosphorus uptake, increase nutrient use efficiency, increase nutrient uptake, stimulate root growth, expand root absorption and-or control diseases and nematodes. With assistance from team member and University of Illinois professor emeritus and Extension agronomist Emerson Nafziger, they began by studying the validity of the claims at over 100 test sites.

“We found after testing at sites across the U.S. that these products had no impact on soybean yield in the first year of our research. We always do our research for multiple years, so we did research again at 52 stations the following year across 20 states. We looked at an expanded list of biological seed treatments and we saw very similar results – that there is minimal impact on yield from biological seed treatments,” said Vann, adding that future studies will focus on identifying geographical regions that could benefit from biological seed treatments more than others due to variations in soil types and climate.

Vann concluded her presentation by touching on late-season soybean desiccation decisions. She noted that due to climate shifting, soybean desiccation is getting more attention in Illinois. Possible reasons to consider late-season desiccation include earlier facilitation of fall soil management practices, mitigating seed quality declines, or to capitalize on maximum crop maturity or high prices for a crop.  

“The optimal time to desiccate is not the same all across the United States; you have a lot of variability in soybean growth habits. This is the reason we are doing some research on this. We are looking at the impacts of soybean desiccation on quality and yield all over the U.S. In Illinois, this could be of great interest in the coming years,” Vann said. 

The ISA’s Aug. 8 “Field Talk” event was at the Heartland Community College Ag Complex in Bloomington.