EQUIPMENT
This method involves broadcast seeding the cover crop using a variety of spreading equipment. This could include aerial application, air seeders or equipment with spinners or pendulum spreaders. Cover crops could be combined with dry fertilizer prior to application. Seeding rates should be increased to account for poor seed to soil contact, seed predation, and residue interference.
Current recommendations for broadcast seeding are:
- Increase seeding rate 20 to 50 percent more than drilled rates to achieve adequate stands. See the Cover Crops Field Guide or consult the Midwest Cover Crop Council cover crop selector tools for recommended seeding rates for each species.
- Good soil moisture at seeding and 0.5 to 1 inch of rainfall after seeding will improve germination and establishment. Compacted or crusted soils may reduce establishment.
- For aerial seeding, weight limitations may make large seeds and/or high seeding rates too costly to be practical. Mixing in a small seeded cover crop can help to keep costs low with a reasonable stand (i.e. mix turnip into oats). Wind, equipment, calibration, height above ground, and speed affect the uniformity of seed distribution. Contact your local agriculture pilot for details on cost, weight limits and distribution. Consult state or regional agricultural aviation associations or the National Agricultural Aviation Association to find aerial seeding pilots.
- Be aware that small-seeded cover crops (grasses, radishes) germinate better from aerial/broadcast seeding than large-seeded cover crops (cowpeas, winter peas) due to seed placement and cracking.
- For late fall broadcast seeding, winter cereal grains tend to be more successful.
- Broadcasting a mix of cover crop species can be difficult as different seed sizes will spread differently and may create bands in the spread pattern.
This method involves broadcast seeding the cover crop onto the soil surface after the cash crop has been harvested, and then using shallow or light tillage to incorporate the seed. Any of the methods under Broadcast Seeding Without Shallow Incorporation can be used prior to incorporation. This method has been combined into a single operation with air-seeders mounted to vertical tillage tools, harrows, and rotary hoes.
Current recommendations for broadcast seeding with incorporation are:
- Make sure there is adequate soil moisture and that seed is not buried too deep.
- Be aware that rainfall after seeding helps, but is not as critical as with aerial seeding or broadcasting on the surface.
- Due to differences in seed size and density, check distribution and spreading when seeding cover crops to minimize uneven stands.
- Increase seeding rate 10 to 20 percent more than drilled rates to achieve adequate stands. See the Cover Crops Field Guide or consult the selector tool for recommended seeding rates for each species.
(vertical till)
This method uses a seed drill to plant the cover crop after the cash crop is harvested. Minimizing soil disturbance by using no-till drills has additional benefits to soil health.
When using this method:
- Be aware that drilling cover crop seed improves seed-to-soil contact, but hard soils, soil compaction, soil crusting, or inadequate soil moisture may still reduce seed germination and establishment.
- When planting mixes, distributing large and small seeds between the main-seed box and small-seed box (if available) can prevent seed segregation and improve seed placement.
- Take time to adequately set up the drill for good seed depth placement and spacing. Read your seed drill owner’s manual or consult a dealer for cover crop seeding rate settings. It is always a good idea to calibrate your drill and it is worth the extra time to calibrate for mixes. If possible, check the rate by turning gears manually in the shop or on a hard surface, and then collecting and weighing the seed output. Penn State University Extension (extension.psu.edu) has a useful article about drill calibration titled, “Calibration of Grain/Seed Drills.”
This method involves using a row crop planter after the cash crop has been harvested. Varying row widths are used including split row planters. Row crop planters generally result in the best cover crop establishment due to good seed-to-soil contact, good depth control, and consistent seed spacing. Minimizing soil disturbance by using no-till planters has additional benefits to soil health.
This method requires 10 to 50 percent less seed than drilling.
When using this method:
- Read your planter owner’s manual or consult a dealer for cover crop seeding rate settings. Planters may require special seed plates, cup holders, brushes, or planter modifications to adequately plant cover crop seed, depending on the type and size of seed selected.
- Additional disks for the seed meters are becoming available for several brands of planters to meter a broader range of cover crop species.
- Through the use of guidance and precision planting systems, the relationship between cover crop and cash crop placement as well as seeding rates can be optimized.
This cover crop interseeder allows for the drilling of cover crops between the rows in standing corn up to V6 by increasing the clearance and modifying the unit spacings. Nitrogen side-dressing capability has been added to some units which allows for combining both operations in a single pass.
Air delivery seeders can be mounted to the tool bars of rotary hoes and harrows to deliver the seed to the soil as the residue is lifted or cut. This method can provide better seed to soil contact than surface application alone, particularly in fields with heavy residue cover.
High clearance sprayers have been equipped with air seeders and drop tubes to allow for cover crop seeding in taller standing corn, nearer to maturity. The recommendations for Broadcast Seeding without Incorporation above apply to this method.
Air delivery seeders can be mounted to harvest equipment. When mounted behind the head (recommended), this allows delivery of the seed to bare soil under or near the head and any residues exiting the back of the harvest equipment are spread as mulch over the seed. This allows for improved seed-to-soil contact, moisture retention and emergence rates over broadcasting alone. When mounted at the rear, seed may fall on top of residue, diminishing seed-to-soil contact and the Broadcast Seeding without Incorporation recommendations above apply. Limitations on hopper capacity may result in frequent filling, increasing harvest time. Smaller seed sizes can reduce filling frequency.
This method involves mixing cover crop seed with slurry manure. The nutrients in the manure promote rapid cover crop growth and the cover crop takes up manure nutrients, especially N, which prevents losses.
There are a variety of methods for seeding cover crops before or after manure application. Conventional methods have manure applied followed with a tillage pass to incorporate manure and the broadcast cover crops.
In recent years, slurry seeding (pictured below) has become popular. Three different methods of seeding the cover crop with the manure are:
- Mixing cover crop seed with manure in the tanker. In this scenario it is important to have a continuous agitation of the manure in the tanker. Cover crop seed should not be left in the tanker for an extended period, since salt content of some manure types (i.e., finisher hog manure/digestate) can reduce the viability/germination of the seed
- Adding a seeder to the tanker where cover crop seed is directed into the injection strip. Toolbar setup will determine if seed is spread ahead or after the manure injection
- A cover crop seed continuous delivery system placing seed into the drag hose system at manure storage.
One pass application, improved seed placement, added moisture, and reduced compaction risk are all benefits. The interaction of manure nutrients with cover crop growth and the benefits to the soil microbial populations and increased biomass production can be significant.
As the drone industry evolves, new uses of drones continue to be discovered. One of these is aerially seeding. Presently this is typically being done with eight propeller battery powered drones. The drones have a cargo capacity of about 15 lbs. with a spreader width of about 15 ft. depending on seed type. Some advantages drones may have for seeding cover crops includes seeding small irregular shaped fields prior to harvest, ability to apply customized seeding mixes for flexibility in grazing systems and can respond quickly to changing weather conditions. Challenges to the use of drones are their availability, limited payload capacity and small acreage seeded per battery.
