Aerial seeding

Aerial seeding is a technique of sowing seeds by spraying them through aerial mechanical means such as a drone, plane or helicopter.

Aerial seeding is considered a broadcast method of seeding.[1] It is often used to spread different grasses and legumes to large areas of land that are in need of vegetative cover after fires.[2] Large wildfires can destroy large areas of plant life resulting in erosion hazards.[2] Aerial seeding may quickly and effectively reduce erosion hazards and suppress growth of invasive plant species. Aerial seeding is an alternative to other seeding methods where terrain is extremely rocky or at high elevations or otherwise inaccessible.[3]

Helicopter Aerial Seeding
Hughes 500 Helicopter Aerial Seeding

Aerial seeding is also often used to plant cover crops. Below is a small list of plants that are often seeded by this method.[4]

Perennial Rye, Sudan grass Soybeans, Buckwheat Hairy Vetch, Corn
Cereal Rye, Winter Wheat Oats, Mammoth or medium Red Cover Sweet Clover, Berseem Clover
Crimson Clover, Perennial Rye Timothy Perennial Rye Red Fescue, Perennial Rye Bluegrass Perennial Rye Red Top, Red Clover Timothy

History

According to the National Agricultural Aviation Association, the birthplace of aerial seeding in America happened 1921 in Ohio. Lt. John A. Macready, a U.S. Army pilot, used a modified Curtis JN-6 to dust a field of catapla trees with arsenate to kill sphinx moth larvae.[5] This early crop dusting led to aerial seeding.

Aerial reforestation, a type of aerial seeding, specifically to repopulate forest land after some type of disaster was being used as early as the 1930s. Planes were used to seed mountain areas in Honolulu that were inaccessible to traditional methods after forest fires.[6]

By 1946 aerial seeding was being used in Oregon to seed more than 500 acres of Douglas fir, and Port Orford cedar as well as 100 acres of grassland and other trees that were burned by fire. In 1947 the Crown Zellerbach Corporation seeded over 1000 acres in Oregon.[7]

Surplus planes from World War II were initially used for aerial seeding, with the open cockpit Stearman biplane used frequently. Because many veterans were trained to fly these planes, this led the way for many people to develop a business around aerial applications. Today professionals use planes powered by turboprop engines and are navigated by GPS for better accuracy.[7]

Major advantage

The major advantage of aerial seeding is the efficient coverage of a large area in the least amount of time. Aerial seeding facilitates seeding in areas that otherwise would be impossible to seed with traditional methods, such as land that is too hard to reach by non aircraft or ground conditions being far too wet. Aerial seeding may be used when existing crops are already planted. This is important when living in an area where there is a small window between harvesting the crop and the end of the growing season, because seeding cover crops after harvest can cause poor stand establishment due to cold temperatures or moisture.[4]

Soil conditions

Soil moisture plays a large role in the success of aerial seeding. Adequate soil moisture for germination and establishment of seed requires that the top 0.5 -1 inch be moist. These conditions should be at the time of the seeding or within 10 days of the seeding. If the required soil moisture is not present at these times, the seeds may become the target of predation by insects and other animals. Along with soil moisture, surface conditions also play a key role in the success of aerial seeding and establishment of seed.[4]

The best soil surface conditions are those that are moist and friable. A loose and rough soil surface with cracks or residue cover is also very conducive to seed germination. These conditions allow for the seed to make the best contact with moist soil while adequately allowing the seed to settle into the ground. Another important factor besides soil surface conditions are that of timing of aerial seeding and seeding rates.[4]

Timing and seeding rates

When aerial seeding a cover crop, one must seed them at least 7 to 10 days before drilled cover crops. The reason for this is because the aerial seeding method is slower than that of the drilled method. Seeding rates for most plants should be 25% to 50% higher with aerial seeding, when compared to other more conventional methods like drilling. These higher seeding rates are needed to establish same yields as other methods. This is mostly because, with aerial seeding, the seed can be often on the soil surface longer, making the seed more susceptible to predation by birds, insects, and other animals.[4]

Helicopter vs. plane

There has been much debate with regards to which type of aircraft is better for aerial seeding. There is some evidence that shows helicopters may be best at the job when seeding in fields that are already established. This is because the wind from the blades of the helicopter causes the canopy of the already established crop to shake and open. This allows for more seed to reach the soil below. Another advantage for the helicopter is they are more maneuverable and can handle irregular shape fields while a plane has a harder time with such fields. The real advantage of the plane is it is faster than a helicopter and has the ability to carry a much heavier load. This allows the plane to finish the job much faster which equals less money spent in the air.[4]

See also

References
  1. "Jeffers, D. L., & Beuerlein, J. (2001). Aerial and Other Broadcast Methods of Seeding Wheat" (PDF). osu.edu. Archived from the original (PDF) on 2003-08-03. Retrieved 2012-03-08.
  2. "U.S Department of the Interior, U.S. Fish and Wildlife Service (n.d.). Aerial seeding". fws.gov. Retrieved 2012-03-08.
  3. "U.S. Department of the Interior, Bureau of Land Management". blm.gov. Archived from the original on 2013-11-26. Retrieved 2012-03-08.
  4. "U.S. Department of Agriculture, Natural Resources Conservation Service". usda.gov. Retrieved 2012-03-08.
  5. "History of Agricultural Aviation". agaviation.org. Archived from the original on 2012-03-14. Retrieved 2012-03-08.
  6. "Could Military Strategy Win the War on Global Warming?". howstuffworks.com. Retrieved 2012-03-08.
  7. "Airplane Seeding: A new Venture in Reforestation". fao.org. Retrieved 2012-03-08.
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