Wrong. Switchgrass does not fix nitrogen like members of the legume family http://www.extension.iastate.edu/Publications/AG200.pdf. Moreover, corn is rotated with soybeans (and winter wheat in areas such as where I live) so that the corn does not deplete the fields so rapidly. Even with rotation nitrogen must be applied for corn.
Wrong. Switchgrass does not fix nitrogen like members of the legume family http://www.extension.iastate.edu/Publications/AG200.pdf. Moreover, corn is rotated with soybeans (and winter wheat in areas such as where I live) so that the corn does not deplete the fields so rapidly. Even with rotation nitrogen must be applied for corn.
You're correct, Switch Grass is a C4 Carbon Fixer, not a nitrogen fixer.