Jarrod O. Miller, Extension Agronomist, jarrod@udel.edu and Amy Shober, Extension Nutrient Management and Environmental Quality Specialist; ashober@udel.edu
In 2021, we studied how small additions of sulfur (S) to starter and combinations of S and boron (B) to sidedress applications affect nutrient uptake and yield in corn as a part of a Maryland Grain Producer and Utilization Board sponsored fertility study. Both S and B are important nutrients to study in Delaware, as our sandier, low organic matter soils may possibly lack both nutrients. In past studies, we have seen strong relationships between nitrogen (N) and S in corn, where both are increasing in corn ear leaf tissue together. Because all three nutrients (N, S, and B) are most likely negatively charged ions in the soil, we tested whether additions of S (4 lb starter and 18lbs sidedress) and B (0.5 lbs) would affect overall uptake into the corn plant.
Although we have observed S deficiencies in our past studies, additions of S did not increase S concentrations in plant tissue or have any effect on corn yield (Figure 1). Adding B at sidedress in combination with S increased tissue concentrations (Figure 2) but had no effect on yield. Interestingly, additions of B also increased K within the plant tissue (minor effect), while applying higher rates of N and S decreased K uptake. Based on drone imagery, this effect was stronger after sidedress of N+S+B occurred, where corn “greenness” increased with K uptake, but decreased with Ca and Mg uptake.
These results reflect the first year of the study and, as such, results may not be repeatable in future years. However, if you are considering B additions to your corn fertility, it may be possible that applying B with Nsol or ammonium sulfate can improve B uptake. All micronutrients, including B, can be toxic when added at excessive concentrations. Follow your label recommendations (typically 1lb or less) based on the product you have purchased.
Figure 1. Yields from the treatments where N+N = starter + sidedress.
Figure 2. Corn earleaf tissue concentrations of B by starter + sidedress applications of N, S, and B.