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COVER CROP
CULTIVATOR SUMMER EDITION • 2020
COVER CROPS AFTER EARLY HARVEST: THE OPTIONS ARE WIDE By Matt Leavitt Organic Lead / Agronomist
Producers looking to maximize crop species diversity are faced with our short growing seasons in the Upper Midwest; it simply is challenging to plant a wide number of species after grain corn or soybeans. The after-earlyharvest planting window (July15 – August 15) is an optimum time to plant a diversity of cover crop species. Adapting your crop rotation to include small grains, silage corn, field peas, dry beans, canning vegetables, and forages is one of the best ways to create a wider window for seeding cover crops. As with any cover crop, you need to consider what your end goals are and what crops will come next in rotation. Changing your rotation may not be feasible for every operation, but below are some cover crop options for various crops.
AFTER SMALL GRAINS/CANNING VEGETABLES/SWEET CORN/DRY BEANS/FIELD PEAS General Recommendations: Time seedings with forecasted rains. Ensure good seed-to-soil contact. Know what cash crop is next in rotation to avoid potential issues. •
Summer Annuals for Biomass/Soil Building (seed up to August 15): SummerMax CC6, SoupMax CC10, Buckwheat, Sorghum/Sudan, Forage Sorghum, Cowpeas, Soybeans
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Summer Annual for Forage (seed up to August 15): Sorghum/Sudan, Forage Sorghum, Sudangrass, Millets, Soybean
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Cool-season Species for Soil Building (seed from August 1 – September 15): NitroMax CC1, ValueMax CC2, WinterMax CC3, GrazeMax CC4, AerialMax CC5, MultiMax CC7, FixMax CC11, Brassicas (radish, forage rape, turnips), Oats, Winter Rye, Peas, Annual Ryegrass
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Cool-Season Species for Forage (seed from August 1 – September 15): NitroMax CC1, ValueMax CC2, WinterMax CC3, GrazeMax CC4, Oats, Winter Rye, Peas, Annual Ryegrass
UNDERSEEDING INTO SMALL GRAINS General Recommendations: Use small seed box on the grain drill. Watch seeding depth. A very common practice is to underseed spring small grains with clover, alfalfa, and mixes like our Plowdown Blend CC9 that are plowed down for fertility following harvest. Similarly, winter grains can be frost-seeded with small seeded legumes. The advantage of underseeding is that the cover crop is already established when the small grains come off which minimizes additional passes through the field.
AFTER SILAGE CORN General Recommendations: Time seedings with forecasted rains. Ensure good seed-to-soil contact. Know what cash crop is next in rotation to avoid potential issues. •
Cool-Season Species for Soil Building (Seed up to September 15): NitroMax CC1, ValueMax CC2, WinterMax CC3, GrazeMax CC4, AerialMax CC5, MultiMax CC7, FixMax CC11, Brassicas (radish, forage rape, turnips), Oats, Winter Rye, Peas, Annual Ryegrass
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Cool-Season Species for Forage (Seed up to November 15): Winter Rye
Flying On Cover Crop Seed Steier Ag Aviation • Algona, Iowa
by Chaunce Stanton Marketing Manager
Like Albert Lea Seed, Steier Ag Aviation of Algona, Iowa, is a third-generation, family-owned business. A lot has changed since 1954, when Tony and Chad Meyer’s grandfather started with 20-gallon capacity in airplanes. (Chad is pictured above in the cockpit.) “Now we’re up to 500-gallon and even 800-gallon capacity in the planes,” Chad Meyer said. “My grandfather used to do 20-acre loads, and now we’re doing 250-acre loads. If a farmer’s field is close to the airfield, we can do a seed load about every 15 minutes.” Steier Ag has expanded its business from just aerial liquid application to becoming a full agricultural retailer of seed and chemical supplies – and aerial cover crop seed application, of course. Their typical
range is about a 60-mile radius from Algona, but they often fly further, depending on the volume of seed required. Chad said they’ve seen a spike in cover crop seed application over the past five years. “About 95 percent of the cover crops we fly on are oats and rye around here. We do some turnips and radishes. We’ve even applied some hairy vetch in mixes.” After removing the liquid system from the plane, they attach a 13-foot-wide stainless-steel spreader, which disperses the seed in about an 80-foot wide spread pattern. The hopper is pressurized and pushes air down on the seed.
Timing Aerial Seed Application
Loading the hopper with cover crop seed.
“Our liquid season goes through August, so we like to wait until late August to start cover crop seeding. We have gone as late as October, but we recommend September for aerial seed application.”
The Big Advantage of Flying On Seed “The big advantage is that we’re not going to run over the corn crop just to get the cover crop in on time.”
Cost of Aerial Application Steier charges by the pound—about $12.50 to $15 per pound, depending on the seeding rate and the distance from the airport.
Challenges in Flying On Cover Crops Chad said that calibrating for seed size can be challenging for certain mixes or for unique seed. “We do cover crop mixes, and for those we calibrate for the largest seed in the mix. Calibrating for radishes, which is a tiny seed, in a mix can be tricky.” Chad added that their goal is to apply the cover crop seed at an accurate rate, based on the farmer’s specifications. “Small orders, like 12 acres of a unique seed or at a unique rate, can be a challenge. We want to get that seeding rate right. We can adjust the flow rate on the fly, but we can’t see the seeds in the hopper from the cockpit, so we can’t always tell how fast they’re flowing. And tiny seeds, like radish, we can’t see coming out in the air, unlike larger seeds like rye and oats. It takes a little learning to get the calibration right so we can be accurate.”
Chad Meyer points out where the seed is released during aerial application of cover crop seed.
Albert Lea Seed is working the University of Minnesota on a promising new variety of hairy vetch. Our grower/research partners at Prairie Sky Farm are increasing that new variety this year in Wesley, Iowa.
HAIRY VETCH
IMPROVING WINTERHARDINESS GUEST CONTRIBUTOR Nick Wiering Graduate Research Assistant Dept. of Agronomy & Plant Genetics University of Minnesota
What Is Hairy Vetch & Why Should Farmers Care? Hairy vetch (Vicia villosa R.) is a member of the vetches, which were among the earliest groups of plants domesticated by humans. It can more reliably overwinter compared to other legume cover crops (e.g. winter pea, crimson clover) and has the potential to provide >150 lbs. N per acre if grown to maturity because of the high N content within its tissue. Like other cover crops, hairy vetch can further provide ecosystem services such as reducing soil erosion and improving soil health. It is also an excellent source of food for pollinators, especially bumblebee species.
Why the Focus on Hairy Vetch? The UMN hairy vetch breeding program was initiated to develop a winter-hardy legume cover crop specifically for Minnesota cropping systems. Legumes are a valuable component to any cropping system because they have the unique ability to convert atmospheric N into plant-usable N in collaboration with soil microbes. However, few winter-annual legumes are able to reliably overwinter in the harsh extremes that Minnesota has to offer. If the plants cannot survive, the full benefits of cover crops cannot be realized. Hairy vetch, which originates from higher altitudes and latitudes in Eurasia, is likely the best candidate to fill this void in the Upper Midwest because it is the most winter-hardy cultivated annual legume. However, until recently there has been little knowledge about what seed sources of hairy vetch are best adapted to northern Midwest conditions.
What Is the Breeding Program Trying to Solve? Cover crops have had few resources allocated towards their improvement compared to major commodity crops like corn, wheat, and soybean. Many cover crop populations, including hairy vetch, still retain some weedy characteristics from their wild ancestors such as pod shatter and seed dormancy. In collaboration with the national Cover Crop Breeding Network, we are identifying plants that lack these characteristics and are finding the genes that may be responsible for them. Like other legume cover crops, hairy vetch can be slow to establish in the fall and regrow in the spring. To address this, our UMN program has aggressively selected for plants that can provide maximum biomass and ground coverage in the fall and early spring. Like any other breeding program, traits such as disease and pest resistance, biomass yield, and seed yield, are still important and carefully scrutinized to develop a wellrounded cultivar. Improving winter survival is a challenging task for any crop due to the underlying genetic complexity of the trait. Testing survival over numerous winters and locations is resource intensive, but generally necessary. However, the UMN team has developed indoor
screening methods to measure freezing tolerance and are currently identifying anatomical and physiological mechanisms that influence winter-hardiness. With these methods, they hope to speed-up the process of developing winter-hardy cultivars.
Who Are the Key Players in the UMN Hairy Vetch Breeding Program? Beginning in the mid-1990’s, Drs. Nancy Ehlke and Craig Sheaffer (Department of Agronomy and Plant Genetics, University of Minnesota) began gathering sources of hairy vetch from the National Plant Germplasm System and local farmers. They evaluated the winter survival of these seed sources over multiple years and environments to identify the most promising populations. In 2015, they received funding through the Minnesota Department of Agriculture’s AGRI Crop Research Grant to use these elite populations as the foundation of a new MN hairy vetch breeding program. Nick Wiering, a PhD candidate working under Drs. Ehlke and Sheaffer, has been leading the breeding program since he joined the team in 2015 as a Master’s student. In 2016, the UMN team joined forces with a USDAfunded cover crop breeding network (grant no. 201851300-28424; covercropbreeding.com) focused on developing regionally adapted cover crops throughout the US. This objective is facilitated by a diverse network of researchers (i.e. academia, USDA, and private research institutes) that enables the exchange of knowledge and germplasm. This sort of collaboration will be vital for the continued improvement of hairy vetch and other legume cover crops.
“Hairy vetch is the most winter hardy annual legume cover crop. Many varieties consistently survive northern Midwest winters. When planted in August or September and killed in May, hairy vetch supplies nitrogen for demanding crops like corn. Hairy vetch also pairs well in a cover crop mix, if seeding rates of highly competitive companion grasses like rye and triticale are not too high. Despite its many benefits, hairy vetch can create major weed problems for rotations including small grains. The Cover Crop Breeding Network aims to release varieties with proven winter hardiness and soft seed. Until variety stated lines are available, however, be sure to source seed with documented winter hardiness in the northern Midwest and keep hairy vetch out of rotations with small grains.”
Lisa Kissing Kucek, PhD Plant Research Geneticist USDA-ARS
NINE THINGS THAT CAN GO WRONG WITH COVER CROPS By Matt Leavitt Organic Lead / Agronomist
Margaret Smith, PhD Agronomist
Research and practical on-farm experience demonstrate that cover crops work for nearly all farm systems. They improve soil health, soil productivity, water quality, and long-term environmental health; however, any new management practice brings learning opportunities and unintended consequences – and cover crops are no exception. Here are nine unintended consequences that may arise with cover crops and a discussion of solutions. #1 Seeding Challenges & Poor Stand Associated cover crop species: Any Cover crop stands sometimes are spotty or inconsistent from year to year—especially when cover crops are broadcast, flown on, interseeded into standing crops or seeded outside of the recommended planting windows. SOLUTION: Treat your cover crops like your cash crops. The more you can plant or drill your cover crops at the right time, optimum depth, right rate, with good seed-to-soil contact, the better establishment you’ll have. Keep an eye on the weather and try to time seedings with forecast rains. Keep your cover crop planting within the appropriate planting window. #2 Winter Survival When You Expected Winterkill Associated cover crop species: Rapeseed, radish, turnips, annual ryegrass, crimson clover Normally radish, Dwarf Essex rape, and other fall-planted cover crops like turnips, kale, annual ryegrass, and crimson clover, consistently winterkill, especially in the north. We’ve learned that early planting (before Aug. 1), mild winters, and abundant fertility can lead to cover crops overwintering including some brassicas.
Figure 2 and Figure 3. Same field as Figure 1, but in the Spring of 2020 with overwintered brassicas. #3 Winterkill When You Expected Winter Survival Associated cover crop species: Hairy vetch, winter rye, camelina, winter peas, crimson clover Cover crops that winterkill when you expect them to survive are a disappointment, but not devastating. Susceptibility to winterkill for typically winter-hardy cover crops varies by species. Fall planting date, biotype, winter conditions and latitude are all factors affecting survival. For winter rye, planting before mid-August in the Upper Midwest can lead to too much vegetative growth in the fall and susceptibility to winterkill. Conversely, seeding rye extremely late can also lead to spotty stands as seed will germinate at different times and can winterkill or die from lack of moisture.
Figure 1. CC2 and Radish in the Fall of 2019 SOLUTION: Plant brassicas after August 1. Conventional farmers can control overwintering species with burndown herbicides. Annual ryegrass can be more stubborn to kill but timing application at the right growth stage should control any escape. For organic producers, a spring tillage pass or two should control most overwintering species. In addition, some organic producers may design cover crop mixes with fewer brassicas and annual ryegrass (depending on planting date, rate, and intended fall/spring tillage).
For hairy vetch, seeding mid-August to mid-September with a spring or winter small grain enhances winter survival potential. Later planting often results in winterkill. Northern growers should select biotypes adapted to, with the seed grown, in the north. Austrian winter pea and crimson clover almost never overwinter in the Upper Midwest. They are winter annuals adapted in far southern Iowa, central and southern Illinois and further south. SOLUTION: Explore a spring planting; however, if you plant corn in April there is simply not enough growing degree units to capture much of any benefit from spring planted covers. Keep seed costs low; oats are usually a safe, inexpensive bet for early spring planting. For weed management, an
additional tillage pass or herbicide treatment may be needed. Organic growers hoping for nitrogen fixation from spring-planted legumes may need to substitute manure or switch to a crop that requires less N. Associated cover crop species: Rye, ryegrass, daikon radish
Can cover crops contribute to crop diseases? This has not been widely documented, other than in a few key instances. Pythium root rots and fusarium can be transferred from winter rye to a following corn crop. In addition, some cover crop species, including crimson clover, pea, sweetclover, hairy vetch, alsike clover and cowpeas, are alternate hosts for soybean cyst nematode.
Species with extensive root systems can potentially plug tile lines, especially those that are close to the soil surface on heavy or poorly drained fields. This characteristic is not unique to cover crops; any plant (including corn, alfalfa, annual ryegrass, radish and weeds) can plug tile lines. As a general rule, roots won’t grow into air so properly installed tiles are essential. Cover crops (like radish) can greatly enhance drainage.
SOLUTION: Know your insect and disease life cycles. For best insect and disease management, avoiding planting cover crops and the following crop that are in the same plant family. For example, in the grass family: avoid rye before corn or oats before wheat. In the legume family, avoid crimson clover before soybeans. Corn, in particular, has suffered both disease and insect pest issues when following rye or wheat cover crops.
SOLUTION: Lower seeding rates of radish and ryegrasses in mixtures if you’re concerned about species plugging tile lines. Delaying planting can also lessen deep rooting; but keep in mind, deep roots are part of the benefit of cover cropping; especially on poorly drained ground.
Organic growers, if tilling in green cover crops, should wait 2.5 to 3 weeks to plant to avoid seed corn maggots feeding on corn or soybeans seed.
#4 Plugged Drainage Tile Lines
Frozen tile lines can also be a culprit for poor tile drainage. If you have concerns position cover crops away from fields with shallow or improperly installed tile. #5 Contaminating the Following Crop Associated cover crop species: Rye, hairy vetch, mustard, buckwheat Small grain growers need to be aware of overwintering species and/or those that set seed including winter rye, hairy vetch, buckwheat, mustard, etc. Food-grade oats, wheat and barley can be rejected at the mill or processing plant for the presence of winter rye, vetch and other contaminating crops. SOLUTION: Pay attention to where you are positioning small grains fields and avoid winter rye, hairy vetch, and other seed-producing species (or species that can shed hard seed) in rotation before planting small grains. #6 Reseeding & Competing with Crops Associated cover crop species: Rye, hairy vetch, buckwheat, mustard, radish, proso millet Cover crops species can be prolific seed producers. Some species will germinate soon after seed shed, such as oats and rye. Others, such as buckwheat, red clover and hairy vetch contain a percentage of dormant and/or hard seed, and may not germinate until the following spring. SOLUTION: Know your cover crop! For easiest management, control cover crops before seed set. If seeds do set and germinate monitor new seedling growth and adjust weed control strategies as needed. Self-reseeded cover crops can sometimes be an advantage in the late summer, after small grains for example. #7 Insect & Disease Host/Pressure Associated cover crop species: Any, particularly grass Insect pests can be attracted to green fields of cover crops and potentially create issues for the following cash crop. Wireworms, seed corn maggot, black cutworms, armyworms, slugs and other species all thrive on green cover crop material, particularly grassy species, and can be detrimental to cash crop seed or newly emerging plants.
#8 Allelopathy Associated cover crop species: Rye, wheat, brassicas, sorghum Allelopathic compounds are water-soluble compounds released into the soil by certain cover crop species (for example, winter rye and to a lesser extent other small grains, brassicas, sorghums and millets) that suppress the germination of small-seeded species—a desirable characteristic if your goal is weed control—but allelopathic compounds can also suppress cash crops as well. SOLUTION: Avoid using cover crops with allelopathic properties in rotation before planting small-seeded crops, such as alfalfa, clover and other forage species. Mediumsized seeded crops may also be affected, such as flax. #9 Residue Management Associated cover crop species: Any Cover crops that leave residue have to be accounted and planned for so that they don’t impede tillage, cultivation, fertilizer, or planting equipment, delay field spring or fall field work or interfere with crop growth and development. SOLUTION: Managing cover crop residue will be part of your operation. You may need to retrofit equipment to plant through or deal with residue (such as changing coulters, modifying row cleaners and/or press wheels and paying close attention to seed-to-soil contact), change the timing of tillage passes, and change your management practices to accommodate the next crop in rotation ( or even adapt your rotation). Cover crops may need to be terminated earlier for complete kill and desiccation or growers may experiment with fall-terminated (either by freezing or herbicides) cover crops to minimize residue management issues. If springs are trending cool and wet, kill cover crops earlier to give soils time to warm. The same would be true for dry springs; killing cover crops earlier will conserve soil moisture.
NEED HELP PLANNING COVER CROPS? Give us a call at 800-352-5247 or email us at albertleaseedhouse@albertleaseed.com
1414 W. Main Albert Lea, MN 56007
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