Scott Wohltman from La Crosse Seeds explains the role that cover crops play in soil health. He will also discuss how growers can integrate cover crops into their operation.

  • What does soil health mean?
    • Continued capacity of soil as a vital living system whereby plant and animal growth, and environmental quality are sustained or regenerated; a holistic approach in which plant, animal and human health are promoted
  • Soil health can be impacted
    • Maximize biodiversity (enhance the rotation)
    • Maximize soil cover with continuous living roots (versus 6-7-month alternative)
    • Minimize disturbance (with less unnecessary tillage)
      • Increased tillage = increase risk of erosion
      • Tillage causes soil collapse
      • Tillage destroys any advance in SOM—cutting water-infiltration rates by half and destroying microorganisms needed to maintain OM levels
  • Winter cover crops catch potential losses between harvest and spring planting
  • Continuous living roots
    • Feedthe soil “food web”
    • Without continuous living roots, soil organisms are short on food
    • Growing plants slow wind & water erosion
  • Erosion
    • Our most productive soil rests near the surface
    • Increased biological activity
    • Greater nutrient availability and organic matter
  • What if we had a cover crop?
    • Biomass would intercept droplets
    • Root channels and earthworm passages increase water-holding and infiltration
    • Roots from covers keep soil in place
  • Tolerable soil losses
    • For most of Illinois, allowable soil losses (or the amount of topsoil that can be replaced) are set between 3 – 5 tons/acre/year
    • Recent data from the Midwest shows we may only be replacing about .5 ton per year
      • It would take a long time to build back an inch, or even half an inch of top soil
  • Effect of Tillage
    • Tillage ecosystems destroy earthwork activity
  • Concepts of Soil Health Improvement
    • Stabilizing, if not improving, soil OM
    • Improving aggregate stability
    • Improving nutrient cycling
    • Increasing water infiltration
    • Increasing water-holding capacity
  • Plant Available Nitrogen (PAN)
    • Legumes provide up to 100 lbs. PAN, but must be killed at bud stage to maximize benefit
    • Cereals immobilize up to 50 lbs. PAN
    • Total N as a % of Dry Matter is a good predictor of PAN
    • PAN can be released as soon as 4 – 8 weeks after cover crop kill, depending on C:N ratio
  • Increasing Water-holding & Infiltration
    • Carbon
    • Converting the sun’s energy into growing biomass helps our soils’ ability to turn excess carbon into organic matter
    • Short term?
      • Deep-rooting covers lead to deeper rooting cash crops
      • Addition of residue helps lessen evaporation
      • Mycorrhizae hyphae
  • Integrating cover crops into the rotation
    • What is my goal and or what am I trying to accomplish?
    • Can I plant a cover crop to achieve my goal given my current cropping system (and when is my current planting window)?
    • Am I willing to make the changes necessary (a real commitment) in order to succeed with this added cover crop?

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