Dual Purpose Oilseed Cover Crops for Sustainable Bioenergy Production.

Sustainable bioenergy production requires innovative cropping strategies to balance food, feed, and fiber production. Dual or double crop strategies might be a way to produce dedicated bioenergy feedstock with food and/or feed crops under highly productive agricultural systems such as those in the Corn Belt region. Camelina (camelina sativa) and field pennycress (Thlaspi arvense) are being developed as relatively low input oilseed feedstock for advanced biofuels. Both have proven to be extremely winter-hardy when grown as winter annual cover crops in the northern U.S. In addition to serving as a cover crop, they can be harvested as a cash crop and mature early enough to allow good potential for double- or relay-cropping (i.e., interseeded) with short-season food and forage/biomass crops such as soybean and sorghum. Winter camelina and pennycress seed yields of around 1000 to 1500 kg ha^-1 are typically achievable and soybean and sorghum following camelina in a dual crop system produce yields as high as 2800 kg ha^-1 and 11 Mg ha^-1 (DW), respectively, in the same season. This type of dual cropping system is a way to integrate dedicated energy crops into agricultural systems without jeopardizing food security. Although dual crop systems are generally more land-use intensive, requiring more agricultural inputs than a single-crop per year system, the environmental benefits offered by incorporating a cover crop may offset the additional inputs. Agronomics of this dual cropping system including economics and in-field energy balance will be discussed.