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Select the Right Cover Crop

Cover crops mimic a workout regimen that benefits your entire body. Likewise, cover crops provide an overall soil benefit.

But would you only do lunges and wonder why your arms aren’t gaining muscle mass?

Cover crops work the same way. If you choose a nutrient scavenger, you shouldn’t wonder why you aren’t making improvements on soil compaction.

“Cover crops are able to capitalize on solar energy during the months when we aren’t growing anything,” says Barry Fisher, an Indiana soil health specialist at USDA-NRCS. “They convert that solar energy with photosynthesis and replace carbon and organic matter back in the soil at times when it would otherwise be losing organic matter – not capitalizing on that solar energy.”

Cover crops provide more than traditional erosion-control benefits. To access these perks, you need to know each cover crop’s specialty and how to manage the different cover crops, says Fisher.

Read on to learn about the benefits of individual cover crops. Then, we list popular mixes for you to consider after you have experience seeding and terminating cover crops. 

Oats

Scientific name: Avena sativa

This annual cereal prevents erosion, scavenges nutrients, suppresses weeds, and adds biomass.

“One of your best tools ahead of corn is just oats,” says Fisher. The rapid fall growth paired with winterkill will provide stored nutrients from the fall to be readily available to the corn crop, he says.

However, if oats don’t winterkill in your area, you may want to terminate the oats a couple weeks prior to planting the following cash crop.

Radish

Scientific name: Raphanus sativus

If you’re new to cover crops, the daikon type radish would be a safe bet as your first cover crop. This brassica is known for its rapid fall growth. Its long taproot, reaching depths of up to 6 feet, is able to bust through shallow layers of compacted soils, which alleviates compaction.

Because the long taproot grows deep into the soil profile, it’s able to scavenge nutrients, which would be otherwise lost to leaching and denitrification, says Tracy Blackmer, research director at Cover Crop Solutions. 

The radish winterkills in most areas, which allows for a hands-off termination program. Unlike some other cover crops, the nitrogen (N) taken up by the radish is usually available early in the spring for the following cash crop.

“As a nutrient pump, those are going to take up nutrients in the fall, hold onto them in the winter, and release N to the subsequent crop next spring,” says Fisher. “Then that really helps you in your nutrient efficiency. It’s a valuable nutrient delivery tool to your corn crop.”

Annual Ryegrass

Scientific name: Lolium multiflorum

Those who have goals centered on preventing erosion, improving soil structure, and scavenging nutrients should consider annual ryegrass, recommends Fisher. This thick, quick-growing grass produces significant deep root biomass that builds soil organic matter, accesses nutrients, suppresses weeds, and curbs soil erosion. The root system of annual ryegrass is dense at shallow depths, but also sends roots deep into the subsoil. Ryegrass can also scavenge leftover N, and provide a timed release of stored N for the following crop.

“You can minimize the N tie-up by waiting a few weeks for the cover crop to decompose before planting the following crop,” says Blackmer.

Annual ryegrass can be terminated by mechanical or chemical means as it overwinters. However, spring termination should be executed before the seed sets for a complete kill and to avoid potential chemical resistance. Annual ryegrass is easiest to terminate before the first node appears, says Blackmer.

Triticale

Scientific name: Triticosecale

Triticale is an easily grown cover crop that is established quickly in the fall.

“It’s an option for farmers looking to graze their cover crop or to add biomass,” says Blackmer.

This winter-hardy grass provides significant ground cover, which helps to suppress weeds. Grazing triticale is an option for livestock producers, says Fisher. Triticale requires spring termination by either chemical or mechanical means.

Crimson Clover

Scientific name: Trifolium incarnatum

This rapidly growing legume provides early-spring N to the following cash crop. In addition to fixing N, it performs well in mixtures. It’s an excellent N scavenger and can help with building soil and preventing erosion, says Blackmer.

Hairy Vetch

Scientific name: Vicia villosa

Hairy vetch is excellent with N fixation. Though not quick to establish, it suppresses weeds once established. Hairy vetch also tolerates drought, which can be an added benefit with volatile weather.

Cereal Rye

Scientific name: Secale serale

“Cereal rye puts down a good root system,” says Fisher.

This cereal has an extensive root system that helps to reduce nitrate leaching. It’s also known for its weed suppression. This easy-to-establish cover crop scavenges N and adds organic matter to the soil. 

If you want erosion control, it’s going to be difficult to beat cereal rye, says Fisher.

If you’re new to cover crops, he recommends planting a cereal rye into standing corn – or immediately after harvest – to allow it to sequester nutrients. In the spring he recommends planting soybeans into cereal rye.

The allelopathic effect of cereal rye provides an option for growers looking for additional weed control. “It’s very hard on small-seeded broadleaf weeds,” explains Fisher.

The cereal rye mats down and robs weeds of sunlight, so even without the allelopathic benefit, it can be complementary to your herbicide program.

Cover Crop Cocktails

Like any workout routine, the more diverse the combination of exercises, the more results you see. Below are four popular mixes to consider when seeding this fall.

Triticale + Radish + Crimson Clover

This trio combines compaction alleviation and N scavenging. The radish’s taproot will bust shallow compaction. The triticale and crimson clover cycle N, making it readily available for the following crop. 

Triticale + Cereal Rye

This mix is ideal for forage production. Triticale provides rapid fall growth; cereal rye provides rapid spring growth. Seeded into cornstalks, this mix can raise the protein level for grazing livestock. The additional protein allows livestock producers to take full advantage of the cornstalks.

Annual Ryegrass + Crimson Clover + Radish

If you’re looking for a balance of fall N uptake, spring growth, and readily available N in the spring, this mix could be for you. This combination also serves as a forage option. Keep in mind, this mix will need to be chemically terminated in the spring.

Oats + Hairy Vetch

This mix can help suppress weeds and provide readily available N to the subsequent crop. Along with its high N production, hairy vetch will provide erosion control in the spring. Oats provide support for the vine to climb.

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