Location: Soybean and Nitrogen Fixation ResearchTitle: Nitrogen fertilizer effect on soybean physiology, yield components, seed yield and protein content in the Southeastern US
Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2022
Publication Date: 7/25/2022
Citation: Epie, K.E., Bauer, P.J., Stone, K.C., Locke, A.M. 2022. Nitrogen fertilizer effect on soybean physiology, yield components, seed yield and protein content in the Southeastern US. Journal of Plant Nutrition. https://doi.org/10.1080/01904167.2022.2084106.
Interpretive Summary: Increasing soybean seed protein concentration is an important goal for farmers and end-users of soybean meal. Although nitrogen fertilizer application may benefit soybean, it is often not used because of soybean’s ability to fix nitrogen in its nodules. We tested whether nitrogen application can benefit soybean seed protein concentration in multiple genotypes on varied soil in the Southeast US, and we simultaneously investigated how nitrogen application affected plant physiology in ways that could be linked with agronomic responses. In our study, there was no variation among soybean varieties in how physiology and harvest responded to nitrogen application. Nitrogen application benefitted yield and seed protein concentration at some locations, indicating that environment-specific management recommendations will be important for increasing soybean protein in the Southeast US.
Technical Abstract: Soybean physiology, seed yield and composition can vary greatly and are a function of genetics, environment, and management practices. N fertilizer is not often applied to soybeans, but it can affect yield and seed composition, and the outcome of N fertilization has varied widely among studies. To test if certain physiological responses might be linked with positive agronomic responses to N fertilizer, a field study was conducted in varied environments unique to the Southeast US. Five genotypes from maturity groups V-VII were evaluated. Although the environment and genotype had significant effects on most of the physiological characteristics and yield components measured, nitrogen application interacted significantly with year for yield, seed oil concentration, and percent of nitrogen derived from the atmosphere in the seed. Nitrogen application interacted significantly with location for yield, seed protein concentration, seed oil concentration, pods per plant, and percent of nitrogen derived from the atmosphere in leaves. Nitrogen application effects did not vary among the genotypes included in this study. A tailored nitrogen recommendation to environment is the best option for improving seed protein in this region with diverse environmental conditions.