Relay and sequential cropping corn with winter oilseed crops in northern climates

Winter oilseed crops camelina [Camelina sativa (L.) Crantz] and field pennycress (Thlaspi arvense L.) are potential candidates for diversifying the corn–soybean rotation in the upper Midwest U.S.; however, little is known about their performance in double cropping with corn. A 2-year study of relay- and sequential-cropping corn with winter camelina and field pennycress was conducted to evaluate such a strategy. Cropping systems did not affect the biomass and grain yield of winter oilseed crops. Overall, biomass, N uptake, and grain yield of winter camelina were, respectively, 3.1, 2.5, and 2.3 fold higher than field pennycress. Over the 2-year study, grain yield of corn in relay was decreased by 18.5% compared to its control; corresponding to 18 and 19% reduction when relayed with winter camelina and field pennycress, respectively. Relative to mono-crop, total grain yield (corn + oilseed crop) and net income of corn in relay with winter camelina decreased 12.9 and 22.9%, respectively, while total grain yield and net income of corn in relay with field pennycress decreased 16.7 and 40.1%, respectively. Over the 2-year study, grain yield of sequential corn increased 13.9% compared to its control; corresponding to 16 and 12% increase following winter camelina and field pennycress, respectively. Sequential cropping maintained or increased total grain yield and net income compared to its control. Our results support winter oilseed crops as candidates to diversify the corn–soybean rotation in northern climates; however, the development of technologies aiming at maximizing grain yield and economic value in double cropping is needed.