High commodity prices have led growers to consider many novel soybean inputs. One input that has garnered considerable attention is the foliar application of sugar products to increase soybean yield.

The objective of this research was to evaluate soybean yield in response to various sources of foliar-applied sugar across four states in the Midwest. Field research studies were conducted at Arlington, Wisconsin; Urbana, Illinois; St. Paul, Minnesota; and West Lafayette, Indiana in 2010.

The four sources of sugar evaluated in this study were:

1. granulated cane sugar
2. high fructose corn syrup
3. molasses
4. blackstrap molasses

All treatments were applied at the equivalent rate of 3 lb sugar a-1 and applied at 15 to 20 gal a-1. The treatments consisted of an untreated check, all four sources of sugar applied at V4, granulated cane sugar and blackstrap molasses applied at R1, granulated cane sugar applied at V4 and R1, and blackstrap molasses applied at V4 and R1.

No positive or negative (phytotoxic) effects were visually observed on the soybean foliage at any location within 10 days following foliar applications (data not shown). Furthermore, sugar did not increase soybean yield within location (data no shown) or across locations [P = 0.60 (Figure 1)], regardless of source.

While this study cannot conclusively prove foliar applications of sugar will not increase soybean yield, the authors conclude that other management strategies to improve soybean yield should take precedence over applying sugar.