Researchers from several Midwestern universities collaborated on a project, funded by the soy checkoff, clarifying several issues ranging from the regional protein concentration of soybeans to the relationship between protein concentration and yield.
Link: https://www.unitedsoybean.org/article/study-builds-on-existing-data-to-confirm-strategic-priorities
Full Research Paper in Nature: Scientific Reports : https://www.nature.com/articles/s41598-018-32895-0