Cover crops are grown outside of the cash crop growing season, usually seeded in the fall and killed before spring planting.
Keeping living roots in the ground year-round can improve water management, soil protection and nutrient scavenging, but they need to be given the same attention as a cash crop to ensure success.
Try cover crops on a small scale at first, and look into cost-share from state and local governments.
Some of the best opportunities are with early-harvested cash crops like corn silage, small grains, and canning crops like beans and peas, as you’ll get more vigorous fall growth if you plant in late summer and early fall.
In fields where wheat was just harvested, simply allowing the wheat to reseed itself without tilling the land would work as a cover crop. But cover crops can work with standard corn-soybean rotations as well.
Learn more about reducing tillage and incorporating cover crops in the Soil Health Series:
Minnesota cover crop recipes
For a quick way to get started, Minnesota cover crop recipes provide step-by-step guidance to some of the lowest-risk starting points for cover crops. These recipes don’t cover all possibilities, but they can help beginners get most pieces in place to incorporate cover crops into a farm operation.
Cover crops reduce erosion in a few different ways.
- Aboveground, living cover crops protect the soil from rainfall impact and reduce the effect of wind. Runoff is reduced along the way.
- Belowground, roots hold soil in place during active erosion events and build structure. Better soil structure means that soil is less likely to erode even if it’s left bare later in the season, such as between harvest and cover crop planting.
- Runoff sediment also contains soil P, so reducing runoff is an important strategy for reducing P loading in surface water.
Infiltration and water management
Cover crop root systems create large channels through the soil to allow increased infiltration. This effect is especially significant for species that have large taproots, but increasing infiltration is reported for other cover crop species as well.
- Increased infiltration means that fields are less likely to stay saturated during Minnesota’s rainy springs.
- Many farmers report dry field conditions more quickly after a rain event when they use cover crops.
Cover crops can also help soil store water by building structure and creating a network of large and small pores.
- Once water enters the soil through infiltration, this pore network retains water for plants to take up as necessary.
- This increase in soil water holding capacity can be especially beneficial in dry years.
Soil nitrate reduction is well-established in Minnesota for a variety of cover crops.
- Nitrate is often left in the soil after fall harvest of corn.
- A winter cover crop takes up soil nitrogen, so less nitrogen is available to be leached. This is an important benefit for reducing groundwater nitrate contamination.
- Farmers should expect some nitrate drawdown by cover crops and plan the subsequent season’s fertility accordingly.
- Soil testing prior to applying N to cash crops can help with field-specific recommendations.
- Benefits of cover crops.
- Choosing a cover crop (consider crop rotation, harvest timing, overwintering, etc.).
- Benefits of biomass production
- How termination date affects biomass production
- Recommended planting dates and seeding rates for cover crops.
- Comparison of cover crop benefits by crop.
- Timing of fall seeding
- Termination timing on biomass production
- How and when fallow syndrome occurs.
- How it affects crops.
- How cover crops can help.
- How to manage fallow syndrome.
Midwest cover crops (available for purchase)
- Research summary: Interseeding cover crops into V7 corn using several species and planting techniques.
- Potential for interseeding cover crops into corn.
- Managing cover crops to reduce competition with corn.
- Optimum seeding time.
- Interseeding strategies.
- Residual herbicides can impact cover crop establishment and growth.
- Considerations for grazing or harvesting cover crops for forage.
- Cover crop sensitivity to herbicide carryover.
- Guidance on mechanical and chemical termination, including carbon-to-nitrogen ratios of common crops.
- Factors affecting residue.
- Pest management tips.
- How to time spring termination for cash crop planting.
Update on latest research
In Cover crop virtual field day: Setting up for success, researchers and educators highlighted research projects that can help farmers and ag professionals successfully incorporate cover crops into Minnesota cropping systems.
Topics & speakers include:
- Cover crops as a tool in waterhemp management?
Ethan Ley, graduate assistant and Gregg Johnson, Associate Professor, Biomass Cropping Systems, Southern Research and Outreach Center, Waseca
- Balancing the pros and cons of planting green in Minnesota
Lizabeth Stahl, Extension Educator – Crops, Worthington Regional Extension Office, Worthington
- Strategies for interseeding cover crops into corn
Axel Garcia y Garcia, Associate Professor, Cropping Systems, Southwest Research and Outreach Center, Lamberton
- Cover crop roundtable
Anna Cates, Extension Soil Health Specialist, Department of Soil Health, Water, and Climate, St. Paul, in addition to previous speakers.