I'm fixing to find out. I planted Austrian Field peas with my winter rye. I ran peas only last year and plowed them in; no fert added, just peas. Came back with a Sudan-sorghum hay crop, no fert and made a good showing. This year I'm going to see if baling the combo is an option, but I did add some NPK this time. Since folks run Alfalfa along with a grass for hay, I don't know why peas wouldn't do just as well to up the TDM and protein.