Professional Development Program






PAGE 61 / 102

Unit 2: Applying Ecological Principles

Selecting the Best Cover Crops. Despite the many benefits of cover crops, they can present challenges and problems if not managed correctly. Agroecosystem managers need to particularly look at the types of cover crops best suited to their location, the effects of the cover crop on the soil water balance, the risks of attracting unwanted pests and the overall cost-to-benefit of planting the cover crop. The following are some important guidelines to assist farmers and ranchers making decisions about cover crops (click on each item for a fuller explanation):

Identify your goals for planting a cover crop. Some of the most common goals expressed by growers include:

  • provide nitrogen
  • add organic matter
  • improve soil structure
  • reduce soil erosion
  • provide weed control
  • manage nutrients
  • furnish moisture-conserving mulch
  • provide habitat for beneficial insects

To plan how and where to use cover crops, look at your rotation, add other key environmental and management information (e.g. rainfall, frost free period, time of heavy labor or equipment in the field), and then look for open periods in each field that correspond to good conditions for cover crop establishment. Consider ways to extend or overlap cropping windows. Some typical niches for cover crops are: winter fallow, summer fallow, small grain rotation with companion-seeded cover crop, and full-year fallow to improve soil.

Refer to your rotation sequence and ask questions such as:

  • How will I seed the cover crop?
  • What’s the weather likely to be then?
  • Should the cover be low-growing and spreading, or tall and vigorous?
  • What weather extremes and field traffic must it tolerate?
  • Do I want it to be naturally killed by winter cold?
  • If not, how do I kill it and plant into it?
  • Do I have the needed equipment and labor?

Based on these questions, some of the key traits to consider are: the cover crop’s growing season (temperature tolerance), its water needs, growth habit, type of root system, soil requirements, shade tolerance, seeding rate and method, days to flowering and maturity, effect on soil nutrients and pest effects.

Once the farmer has identified a goal and niche, and has identified the traits they are looking for in a cover crop, they are ready to select the cover crop that will best suit their situation. There are many resources available to help with this process (see Cover Crop Resources next page). Keep in mind that the best solution may actually be a mix of cover crop species.

After identifying the cover crops that would be best suited for their particular situation, growers are advised to start small and experiment with their choices to see which works best.

Finally, evaluate a cover crop’s impact as you would any other crop, balancing costs against returns in all forms. Don’t limit your calculations, however, to the target cover crop benefit. A cover often has several benefits. Many cover crops offer harvest possibilities as forage, grazing or seed that work well in systems with multiple crop enterprises and livestock.

PAGE 61 / 102