10 Tips for Getting Started With Cover Crops
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Written by Dr. Mary Gumz, PhD, Pioneer Agronomy Manager
Cover Crops | Crop Doctorate
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Key Points
- Cover crops, such as cereal rye, annual ryegrass, oats, brassicas, and legumes are planted to cover the soil between cash crop rotations.
- Well managed cover crops can provide erosion control and improved water quality, as well as scavenge for nutrients and help manage weed populations.
- High yield crop production can occur with cover crops, but successful cover cropping often requires the same time and attention as cash crops.
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1. Know Your Goal with Cover Crops
- Cover crops can be used for a variety of purposes: decreased erosion, improved water quality, improved soil health, decreased compaction, weed control, or nitrogen scavenging or fixation.
- Decide which benefits are most important to you and determine your goal in adding cover crops to your cropping system before selecting your cover crop species or mixture.
2. Select the Right Species or Mixture
- Winter hardy grasses – including cereal rye, wheat, barley and triticale – can be seeded in the fall and will produce above- and below-ground growth before going dormant for the winter. Grasses are good for producing a lot of biomass, carbon sequestration, and soil stabilization due to root mass accumulation. Hardy grasses need to be terminated in a timely manner in order not to compete with the subsequent crop.
- Oats and other non-winter hardy grasses can establish quickly in the fall and accumulate biomass but will winter kill. While oats don’t generally accumulate as much biomass as winter hardy grasses, there is no chance of termination failure and competition with the cash crop.
- Brassicas such as tillage radish or turnip can produce a large taproot to aid in addressing compaction issues but have the advantage of winterkilling with below freezing temperatures and breaking down quickly in the spring.
- Legumes that help fix N include winter pea, hairy vetch, and crimson clover among others. These species can provide N to the field but must be allowed to grow later into the spring which can interfere with cash crop seeding.
- Mixtures of species can also be seeded to obtain multiple benefits.
Previous corn field with emerged cereal rye cover crop.
3. Plant Your Cover Crop in a Timely Manner
- Cover crops need to be planted in a timely manner to establish fall growth and overwinter or provide enough biomass to stabilize the soil before being killed by frost.
- An early maturing cash crop can allow for more timely cover crop harvest in the fall.
- In the central Corn Belt, plant cereal rye or rye grass as soon as possible after corn harvest or interseed with the crop via aerial seeding.
- Interseeding of cover crops should be done late enough to prevent the germinating cover crop from competing with the cash crop during grain fill.
- Legumes need to be able to get 6 weeks of growth in order to fix nitrogen.
4. Terminate Your Cover Crop in a Timely Manner
- The goal is to terminate your cover crop before it interferes with your cash crop. The most common termination methods are rolling/crimping or herbicide application.
- Rolling and crimping grasses involves flattening the cover crop with a roller and crimping the stem to inhibit further root growth. Plants fall in the same direction creating a mat of vegetation for weed control while reducing build up on planter units during cash crop planting.
- Herbicide termination (commonly with glyphosate or a glyphosate tank mix) has more timing flexibility than rolling/crimping. However, spray applications made in weather cooler than 55 °F (13 °C) may be less effective. Tall grass species may fall in multiple directions, hampering equipment movement and planting efficacy of your cash crop.
- If not “planting green,” terminate your cover crop at least two weeks prior to planting.
5. Planting Green
- “Planting Green” refers to planting your cash crop into a living cover crop.
- Planting green into a standing cover crop (6-12 inches, 15-30 cm tall) may make for easier planter movement through the field and better planting of the cash crop. The cover crop must be terminated, though, before it competes with the cash crop.
- Increased top growth of the cover crop from planting green may bring you more benefits such as increased N fixation from legume cover crops.
6. Planting Brown
- “Planting Brown” refers to planting into a terminated cover crop.
- Planting brown terminates the cover crop before the cash crop is planted, eliminating competition for water and nutrients.
Corn planted no-till into rye cover crop, then rye was sprayed with herbicide to terminate it.
7. Adjust Your Planting Practices
- Plant into a fit warm seedbed. Planting can get delayed with cover crops so make sure you are optimizing emergence.
- Maintain a seeding depth of at least 2.5 inches (6.4 cm) for corn and 1.5 inches (3.8 cm) for soybeans.
- Adjust coulters and other planter equipment as needed in order to properly slice cover crop residue and make a clean seed slot.
- In a dry spring where the cover crop growth has used available soil moisture, irrigate after planting, if possible, to ensure timely and even germination.
8. Optimize Your Fertility
- Nitrogen management is key.
- Front load N applications to your cash crop. Up to 50-75 lbs/acre of actual N is needed for a no-till corn crop with a cover crop at planting.
- Use starter with 2 x 2 placement or in furrow to overcome N tie up and place N closer to the root zone. Apply no more than 20 lbs/acre of N on the seed to prevent salt burn.
9. Be Aware of New Pests
- Cover crops can exacerbate problems such as slugs, seed corn maggot, black cutworm, or white grubs.
- Use a fungicide + insecticide seed treatment to protect seedlings from diseases and insect pests.
- Choose a corn hybrid with strong stand establishment and early growth.
- Matted vegetation after cover crop termination can prevent residual herbicide applications from making complete soil contact.
10. Evaluate Costs and Return
- Cover crops require management and are another input cost that will have to be covered by “benefits”. Plan for the benefits you want to see and measure so that you can best evaluate ROI.
- Calculate savings such as decreased erosion, income from carbon credits, reduction of tillage passes, improved weed control, etc.
- Consider costs such as cover crop seed, planting and termination.
- Realize that some costs and benefits may take more than a year to see.
Forage radish or 'tillage radish', a cover crop species that can help remediate soil compaction by producing a large taproot.
References
- Heggenstaller, A. 2013. Managing Winter Cover Crops in Corn and Soybean Cropping Systems. Pioneer Crop Insights Vol. 23 No. 11.
- Hoorman, J.J. 2021. Maximizing Crop Yield at Planting. Ohio’s Country Journal. May 6, 2021.
- Jasa, P. 2015. Planting Tips for Successful No-Till. University of Nebraska-Lincoln Cropwatch.
- Schafer, S. 2021. Success Tips for Planting Green into Cover Crops. Farm Journal AgWeb. March 11, 2021.
- USDA Sustainable Agriculture Research & Education. 2012. Crop Rotation With Cover Crops. Pp 34-43 in Managing Cover Crops Profitably, Third Edition.
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The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. Product performance is variable and depends on many factors such as moisture and heat stress, soil type, management practices and environmental stress as well as disease and pest pressures. Individual results may vary. Pioneer® brand products are provided subject to the terms and conditions of purchase which are part of the labeling and purchase documents.