Jarrod Miller, Amy Shober, Phillip Sylvester
In the summer of 2018, we sampled tissue and soil samples from University of Maryland (Salisbury, Clarksville, Keedysville) and University of Delaware (Georgetown, Marydel) corn variety trials. The goal of the project was to observe whether corn tissue samples across the region were above critical nutrient contents as described by past literature. Two varieties each from the early, middle, and late maturity groups were sampled at each site.
Of thirty tissue samples tested, only two were above the critical nitrogen (N) level of 3%. This may be proof of the wet spring/summer causing losses of N before the roots could take it up. For phosphorus only two samples were below critical concentrations, while potassium (K) had nine tissue samples below a concentration of 2%. A majority of the tissue samples had low values for both calcium and magnesium (Mg), but none were low in sulfur. Interestingly, corn yield decreased as tissue Mg concentration increased, although the relationship was not strong (r2=0.24). With so many tissue samples coming up low for Mg, further research on critical Mg levels are needed. For micronutrients, only zinc had a few samples below critical concentrations, while boron (B) was lacking for almost all samples.
Two nutrients, K and B, had significant, positive relationships with yield across the region. It was evident that some coastal soils lacking in K were holding yield back, but the relationship showed no signs of reaching a maximum at higher yielding sites either. This may point to the need of K across all soils in Maryland and Delaware. As a micronutrient, B can leach easily from soil surfaces before roots can access it. If not added as a fertilizer, most crops obtain B from organic matter. Like K, it is evident that B may be lacking in corn fields across Maryland and Delaware.
Manganese (Mn), a micronutrient, and aluminum (Al) had negative relationships with yield. Aluminum is not an essential nutrient, but plants will take it up from the soil. Both Mn and Al become more available as pH drops, which matches soil pH’s observed across the sites sampled. This can easily be overcome by maintaining a pH that is at least above 5.5.
This project will require several seasons of work before consistent patterns may emerge. However, research in both K and B fertility would probably benefit corn yields in both Maryland and Delaware.
This research was funded by the Maryland Grain Producers Utilization Board (http://www.marylandgrain.org/)
