Technical Abstract: For over two decades, technical experts and policy makers have been encouraging the use of cover crops throughout the Chesapeake Bay watershed as a way to reduce nutrient and soil losses and improve water quality. While such practices have been heavily adopted in some regions, the economic incentives have been inadequate across much of the watershed. With the advent of demand for cellulosic biomass, there is increasing interest in planting energy crops as double crops, intensifying production while enhancing environmental outcomes from management of existing row crop acres. In this study, we predicted biomass production from a winter rye cover crop on corn grain land and soybean land that did not currently have a small grain winter crop. Based on the 2007 USDA Census of Agriculture, the Chesapeake Bay watershed included 604,600 hectares of corn grain and 431,500 hectares of soybean production, of which approximately 489,500 and 370,300 hectares respectively had no cover crop in 2007. Rye yield was modeled using the Integrated Farm System Model (IFSM) adjusting for different typical planting dates and climate conditions across the region. Within the Chesapeake Watershed, the potential biomass from such a double crop strategy is substantial, on the order of 3,500,000 Mg of rye biomass dry matter, providing a significant contribution to sustainable energy, water, and soils.