Cover crops can be used as a long-term tactic to increase your soil health and productivity. But, they can also bring their own challenges and risks. Before deciding which cover crops to include in your management plan, here’s what you need to know – and how to decide if cover crops are right for your farming operation.
Cover Crop Benefits:
Cover crops are most known for providing numerous long-term soil benefits, including:
- Reducing soil compaction and erosion. They can help hold the soil in place, which helps minimize crusting and protects the soil from wind and rain.
- Weed suppression. Cover crops prohibit weed germination and growth.
- Improved soil moisture. Constant soil cover prevents water runoff and increases infiltration.
- Increased organic matter and microbe activity. Cover crop biomass contributes to overall soil organic matter and creates a habitat for microorganisms
- Building a nitrogen reserve. Legume crops fix nitrogen that is mineralized during cover crop harvest, which is then used on future crops.
- Minimal nutrient loss. Cover crops can prevent runoff and leaching, which deprive soil of necessary nutrients.
- Nutrient cycling. With the addition of biomass both above and below the soil, microbial growth is boosted.
- Corn and soybean yield increase. Soil productivity increases in normal cropping systems after cover crops are terminated.
To optimize your acres, you’ll need to make the right cover crop choice – taking into consideration crop species, growing environment, and more. And choosing the right cover crop begins with identifying what your soil needs.
Cover Crop Selection For Your Operation:
Four groups of cover crops can each add their own unique benefits to your farm: grasses, legumes, brassicas, and non-legume broadleaves.
Grass options include winter cereals such as ryegrass, wheat, and barley. These options are most often planted late summer to late fall, then go dormant in the winter. They are valued for their ability to produce biomass, which helps prevent soil erosion, suppress weeds, and increase soil organic matter. Grasses should be planted approximately 30 days before the first expected frost date.
Common legume cover crop options include red and crimson clover, hairy vetch, and field pea. Legumes must be planted earlier than cereals in order to survive the winter. Plan to plant them early summer through early fall for best results. They bring value to your soil with their ability to fix nitrogen. The amount of nitrogen added will vary among the species you select, but will be proportional to the amount of biomass produced.
Brassica options for your farm include turnip, mustards, canola, and forage radish. Brassicas have recently grown in popularity as cover crops. They provide many of the same benefits as grasses, while breaking down easier when it’s time to plant your commodity crop. In addition, some brassicas have a large taproot system that allows them to break down soil compaction. To reap maximum benefits from these warm-season crops, plan to plant your seed in late summer or early fall. In cold regions, most brassica options winterkill and speed up decomposition, which is a major benefit for your soil come spring.
Non-legume broadleaves include rapeseeds, turnips, radish, and buckwheat. They are most useful for scavenging nutrients, especially nitrogen left over in the soil from a previous crop. They can also reduce or prevent erosion and can act as soil cover in a residue management program. Plan to plant non-legume broadleaf cover crops in late summer or fall to establish good roots and prepare the crop for biomass production.
For best results, work with your AgriGold agronomist to determine which cover crops are best for you, depending on your soil health and management plan.
Cover Crop Establishment:
The most crucial aspect of cover crops is plant establishment – which is often the most difficult challenge. For whatever cover crop you choose, optimal timing and practices will vary depending on environmental conditions and your farming operation. Some factors to take into consideration include:
- Seeding date
- Seeding method
- Nitrogen amounts in the soil
Seeding Date: There are three crucial windows of time for proper cover crop establishment:
- In-seed seeding happens during a corn or soybean growing season. This is most effective for cover crops such as brassicas and legumes that work well in low-light, short-season environments.
- Seeding at physiological maturity works best for grasses and grass-legume mixtures. As your typical corn or soybean crop begins to dry down for harvest, sunlight creeps through the canopy, allowing for proper germination of your seeded cover crop.
- Post-harvest seeding is the most common seeding date for cover crops. For most regions, any legume or grass cover crop option can be planted following crop harvest.
Seeding Method: This will depend on which cover crop you’ve chosen, and when you’ve decided to seed. If you choose to seed at physiological maturity, for example, you’ll need an aerial seeding method due to the size of your corn and soybeans at this point in their growing season.
For those who choose to use the post-harvest seeding date, common methods include grain drills, broadcast seeding, and row crop planters. Grain drills are useful in cover crop planting, since most include fertilizer and legume boxes that assist in planting mixtures.
Row crop planters are another way to efficiently plant cover crops. You may have to acquire attachments to add to your row crop planter, but these can help obtain proper seed spacing, depth, and seed-to-soil contact.
Lastly, broadcast seeding methods are effective after grain crop harvest. For best results use an air seeder or floater (mixed with fertilizer) to broadcast the seed.
Nitrogen Amounts: Nitrogen is key to achieving good cover crop establishment. For grass and brassica cover crop options, you will need 30-60 pounds of nitrogen to receive full benefits. Thankfully, regular corn and soybean cropping systems will have sufficient nitrogen amounts left over in soil residue to meet this requirement. For areas with low nitrogen levels or sandy soils, consider adding more nitrogen through a fertilizer application.
Cover Crop Termination: After proper establishment, you’ll also want to choose the right approach for termination. Termination methods include winterkilling, herbicide use, tilling, and mowing. Each method of termination offers a different set of benefits and limitations based on the type of cover crop you used, environmental conditions, your management plan, and upcoming corn or soybean cropping system.
Winterkilling is the most effective method of termination, but is only applicable to certain cover crop varieties. For simplicity, you can choose to use herbicides to terminate your cover crop before reproductive stages, or two to three weeks before corn or soybean planting.
Armed with all the necessary information about properly selecting, growing, and managing cover crops, now it’s time to get started. Identifying your management goals, meet with your AgriGold agronomist, and choose a field to start testing your cover crop options – so you can reap the benefits for years to come.