Soybean response to foliar fertilizer and fungicide

A 2015 on-farm research trial showed foliar applied nutrients and fungicide effects on soybean yield were not significant but merit further investigation.

There is concern among soybean producers that micronutrient deficiencies and foliar diseases are causing yield reductions in Michigan. As such, there is a tendency among soybean producers to apply supplemental nutrient sources and fungicides even without sound experimental evidence to support these practices. In 2015, a farmer was interested in testing the effectiveness of a foliar spray containing Prudent Presto Red Label (6-18-5) plus boron (0.25 percent),manganese (1 percent), humic acids (0.01 percent) microbial fermentation extract (0.01 percent) and the fungicide Priaxor in a tank-mixed application.

This Michigan State University Extension research trial consisted of three treatments:

  • T1 – check treatment with no foliar applied nutrients or fungicide.
  • T2 – foliar applied Prudent Presto at the rate of 1 gallon per acre.
  • T3 – foliar applied Prudent Presto at 1 gallon per acre plus fungicide Priaxor at 8 fluid ounces per acre.

The trial was planted May 29, 2015. The plots were 16 rows wide at 15-inch row spacing. The treatments were randomized and replicated four times. The variety was Liberty Link DL 9261, the planting population was 160,000 seeds per acre and the previous crop was corn. Seed was treated with inoculant prior to planting. The soil was a loam with a pH of 6.7, Cation Exchange Capacity (CEC) of 7.2 meq/100g and soil organic matter of 1.5 percent.

This field received excess rain in June and July and flooded conditions slowed down initial growth and establishment. The Prudent Presto and Priaxor were foliar sprayed on July 27. The application date was originally planned for R1, but was delayed until R2-R3 due to wet field conditions. Soybeans were harvested Nov. 1.

Effects of foliar fertilizers and fungicide on soybean yield - Mason, MI 2015.

Treatment

Grain moisture* (%)

Soybean yield* (bu/A)

Untreated

13.3

52.5

Prudent Presto

13.5

52.6

Prudent Presto plus Priaxor

13.2

56.7

*Soybean yield differences were not significantly different (p<0.05). Yield adjusted to 13 percent moisture. CV = 5.1 percent.

The soybean yield differences between the treatments were not statistically significant (see table), although the treatment containing Pruden Presto and Priaxor combination produced the highest yield in three of the four replications. A point of interest was that there were no visible micronutrient deficiency symptoms in the untreated or treated plots during the growing season. Likewise, there were no visual differences in foliar diseases. All plots appeared to be equally affected by early season flood conditions but recovered well enough to produce acceptable yields. This year’s data support the general consensus that soybean yield responses to micronutrients or fungicides in Michigan are not consistent or predictable.

Michigan soybean farmers continue to show interest in using micronutrients and fungicides. So there is merit for continuing on-farm research towards identifying site-specific factors and practices that would contribute to more predictable yield responses. We intend to test the micronutrient and fungicide combination again in 2016.

This study was funded by the Michigan Soybean Promotion Committee. I’d like to thank Tony Igl, soybean producer from Mason, Michigan; Trevor Kraus, Technical Service Rep, Michigan and Ohio BASF The Chemical Company; Mike Staton, senior MSU Extension educator; and Martin Chilvers, MSU Extension specialist for their support and collaboration in this study.

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