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
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
Converting the sun’s energy into growing biomass helps our soils’ ability to turn excess carbon into organic matter
Deep-rooting covers lead to deeper rooting cash crops
Addition of residue helps lessen evaporation
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?
The Illinois Soybean Association (ISA) checkoff and membership programs represent more than 43,000 soybean farmers in Illinois. The checkoff funds market development and utilization efforts while the membership program supports the government relations interests of Illinois soybean farmers at the local, state, and national level, through the Illinois Soybean Growers (ISG). ISA upholds the interests of Illinois soybean producers through promotion, advocacy, and education with the vision of becoming a market leader in sustainable soybean production and profitability.