Evaluating Canola and Winter Cover in Alternative Cropping Systems in Iowa

Project Overview

Project Type: Graduate Student
Funds awarded in 2010: $9,922.00
Projected End Date: 12/31/2013
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, soybeans, wheat


  • Crop Production: cover crops, crop rotation, double cropping, intercropping, multiple cropping, nutrient cycling, organic fertilizers
  • Farm Business Management: new enterprise development
  • Production Systems: agroecosystems
  • Soil Management: green manures


    The overall purpose of this research project is to provide demonstrations of and more information about practical alternative and sustainable cropping systems for farmers in Iowa. These cropping systems include oilseed, cereal, and perennial legume species uncommon to current Iowa crop rotation, which is primarily dependent on two species, corn and soybean. Improving farmer economic stability and reducing the negative ecological impacts of current Iowa farming practices are additional goals of this project. Three different crop rotations are being evaluated on an Iowa State University research farm. The first rotation (Rotation A) represents a corn-soybean system common to Iowa. The two other rotations represent alternatives to the common and include ‘third’ crops, double-cropping, and legume interseeding. In one alternative rotation (Rotation B), a corn crop will be succeeded by a double- crop of spring wheat and winter canola. In the other alternative rotation (Rotation C), corn will be succeeded by a double-crop of spring canola and winter wheat. The winter annual is planted shortly after the spring annual is harvested, thus providing ample time for the winter annual to establish and the best opportunity for winter survival. Red clover is then frost-seeded into the winter annual (canola or wheat) the following late winter/early spring. The red clover remains after harvest of the winter annual and over-winter into the following spring before being terminated for another corn crop completing the rotation. These latter two rotations ensure winter cover (in the form of a winter annual or perennial legume) in two of the three winters in each rotation. Moreover, these alternative rotations include three cash crops (corn, canola, and wheat) as well as a green manure legume crop (red clover) that may also increase farmer profitability by reducing farm input costs incurred by pest control and fertility requirements. The reduced reliance on these inputs may play a role in reducing the ecological footprint of farming practices. Furthermore, the increased winter cover can serve to reduce system leakages contributing to farm ecological footprint in the form of soil erosion and nutrient leaching.


    The typical Iowa corn-soybean rotation is detrimental to the ecological sustainability of
    Iowa’s soils and agriculture. In this rotation 1) ?elds remain open during the winter, increasing
    the potential for wind and water erosion of soil 2) soybeans host a number of pest management
    problems reducing pro?tability and 3) the crop rotation lacks plant diversity that could enhance
    pest management. The purpose of this research project is to increase crop species diversity on
    the Iowa farming landscape. This will be achieved by developing longer crop rotations that
    include summer and winter annual species as well as perennial species. Oilseed crops such as
    canola and cereal grains such as wheat exhibiting summer and winter annual life cycles as well
    as perennial legumes such as red clover could possibly ?t into an Iowa crop rotation providing
    growers with alternative options. Additionally, the inclusion of summer and winter annual crop
    species in rotations increases the potential of economically viable double-cropping scenarios.
    The inclusion of species with different life cycles such as these can also serve to improve
    cropping systems by increasing the amount of ground cover throughout the year and help
    disturb life cycles of problematic weed species. Incorporating multiple species into a crop
    rotation may also improve yields of other crops such as corn and improve a farmer’s economic
    stability, while at the same time reduce the ecological footprint as a result historical land
    cultivation. The potential to reduce the amount of off-farm, synthetic inputs also exists when
    longer, more diverse crop rotations that include legumes are employed. Before growers can
    reap the bene?ts of alternative crop rotations, the ecological and economical viability of ‘third’
    crops and double-cropping systems must be evaluated with a strong emphasis on making any
    information as a result of this research readily available to growers.

    Project objectives:

    The main objectives of this project are to:
    1. increase the amount of information available to growers regarding canola as an alternative
    oilseed or ‘third’ crop in Iowa;
    2. increase the amount of information regarding winter canola, winter wheat, and red clover as
    cover crops in Iowa; 
    3. assess the ecological and economical impact of the alternative cropping systems to be studied.

    Ecological implications, such as entire-system fertility and mechanical input requirements among the rotations are being assessed. These implications will surely impact the financial competitiveness of the rotations. The diverse rotations generally require more passes through the field, yet costs of seed and fertility may in fact be greater in the conventional rotation making them more expensive. We continue to hypothesize that the reduction of synthetic fertilizer and weed control methods due to the inclusion of the alternative crops, compared to conventional cropping systems, will result in the economical competitiveness of rotations incorporating alternative crops.

    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.