Blog

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?