Rafael A Martinez-Feria, Department of Agronomy, Iowa State University, Des Moines, IA, Mary H. Wiedenhoeft, Iowa State University, Ames, IA and Thomas C. Kaspar, USDA-ARS National Laboratory for Agriculture and the Environment, Ames, IA
Current practices of summer annual crop rotations in Iowa often leave soil bare and unprotected from erosion and losses of organic matter and nutrients during fall, winter, and spring. Winter canola (Brassica napus) might be a suitable crop for providing ground cover and living roots during the winter fallow period and for oilseed production in Iowa, thus enhancing conventional rotations. However, winter survival represents a challenge in the cooler climates of the Upper Midwest. We are investigating the viability and short-term profitability of incorporating winter canola into the corn (Zea mays L.) - soybean (Glycine max (L) Merr.) rotation, as winter cover crop and as cash crop frost seeded with red clover (Trifolium pratense L.). We are testing the effect of seeding date on winter survival, tracking canopy cover and calculating nitrogen uptake of winter canola. We will compare the costs, income and risks of the alternative cropping systems with a conventional corn-soybean system. Preliminary one-year data suggest that delaying seeding beyond 1-September may greatly decrease winter survival, percent canopy cover, N uptake, and biomass and seed yields of winter canola. The final results of this project will serve to increase the information available about the use of winter canola as both a grain crop and as a cover crop, which will be useful for designing strategies that increase the diversity and resilience of cropping systems in Iowa.