Suitability of Winter Canola (Brassica napus) for Enhancing Summer Annual Crop Rotations in Iowa

Project Overview

Project Type: Graduate Student
Funds awarded in 2013: $10,000.00
Projected End Date: 12/31/2015
Grant Recipient: Iowa State University
Region: North Central
State: Iowa
Graduate Student:
Faculty Advisor:
Dr. Mary Wiedenhoeft
Iowa State Univ

Annual Reports


  • Agronomic: canola, corn, rapeseed, soybeans


  • Crop Production: cover crops, crop rotation
  • Production Systems: general crop production

    Proposal abstract:

    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 the performance of conventional summer annual rotations. However, winter survival represents a challenge in the climates of the Upper Midwest. We have recently initiated a series of field trials to test the viability and short-term profitability of incorporating winter canola into corn (Zea mays L.) - soybean (Glycine max (L) Merr.) rotations, as winter cover crop or as cash crop frost seeded with red clover (Trifolium pratense L.). The experiment is being conducted on land following soybean in a split plot design with four seeding date treatments for whole plots in four complete blocks and two alternative rotation treatments for subplots: 1) soybean > winter canola (winter cover crop) > corn (2-year rotation); and 2) soybean > winter canola (cash crop) & red clover > corn (3-year rotation). In addition a control plot has been established in each block for a conventional corn-soybean rotation: soybean > winter fallow (no winter cover) > corn (2-year rotation) (see Figure 1). Preliminary analysis suggests that the ideal seeding date window dates in central Iowa may be the first two weeks of September. We will examine the effect of seeding date on winter survival, determine canopy cover, and calculate nitrogen uptake of winter canola. We will compare the costs, income and risks of the alternative cropping systems with a conventional corn-soybean system. The 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. Ultimately, this would contribute to efforts promoting winter cover crops and alternative crops as viable tools not only for improving soil conservation practices, but also for sustaining profitability of cropping systems.

    Project objectives from proposal:

    -Establish reliable seeding dates for winter canola in Iowa

    -Test the effect of seeding date on the viability of winter canola (Brassica napus) as cover crop and cash crop integrated into corn-soybean rotations

    -Assess the suitability of winter canola for providing short-term economic benefits and for aiding to build long-term cropping systems resilience

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.