Still time to establish cover crops with aerial seeding

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Farm Forum

Aircraft buzzing over fields in the Midwest are taking on increasing importance to farmers. Most times the planes deftly apply chemicals to fields to combat weeds or bugs. Increasingly, however, the planes are equipped with seeders that are mounted underneath the plane.

The aircraft drop seed over corn fields to establish a cover crop that can enrich the soil. This practice allows farmers to establish a cover crop before the corn is harvested, allowing more time for growth before the first frost. Otherwise, farmers would have to wait to plant the cover crop with a drill after harvest.

Eric Barsness, USDA Natural Resources Conservation Service conservation agronomist in Brookings, said farmers are increasingly using this aerial mode of seeding.

Because cover crops are being planted in existing fields of corn, getting them established is a challenge. When the corn plants dry down in late summer, the green canopy opens, presenting the opportunity to establish these covers.

“Late August and the first two weeks of September is the best time frame for seeding,” Barsness said in a telephone interview. “The most important criteria is to seed just before a rain. That gets the seed started in the soil.”

He explained, “Farmers first have to decide what their goal is in planting cover crops. The choices of seeds should be based on the farmer’s objective for that field. The types of seeds planted will make a difference, if the purpose is to graze the field, to improve microbial activities or to improve soil compaction.”

Day County farmer Steve Zubke believes that cover crops are important to help hold soil from wind and soil erosion. Zubke credits Lindsey Goldade and Cindy Zenk in the NRCS office in Day County with getting him started and educated about cover crops.

“I plant cover crops for soil health mostly,” Zubke stated in an email. “Extra grazing could be an added benefit. The cover crops I plant have deep roots, such as radishes and turnips.”

The practice helps infiltration of water and builds soil organic matter over time. Zubke said that certain cover crops help hold nutrients in the upper portion of the soil profile where they are more readily available to plants. He’s very interested in the research showing certain covers are having an effect on reducing soybean cyst nematode counts.

For the pilots, the biggest challenge is coordinating the delivery of the seed and waiting for the right conditions, Loren Greenhoff with Leading Edge Aerial Spraying of Dell Rapids said in a phone interview.

He said the technique is much like spraying.The seed spreader attaches to the bottom of his airplane, with the seed in the chemical tanks.

When seeding, “I’m running at 100 mph, either into or with the wind, to get the same rate of seed over the field,” Greenhoff said. “It works almost like an end-gate seeder. We calibrate the rate before we take off and then fine tune it once we get in the air.”

He believes most farmers plant covers to improve soil health, loosening up the ground. Some say that rye helps with weed suppression. Most cattle people like a mix of radish, rape and turnips, Greenhoff said.

Barsness said the seed mix will vary. Growth of the crops depends on moisture, germination of the seed and the timing of the first killing frost.

Zubke said the only problem with aerial broadcasting cover crops is that it is weather dependent. Moisture is a critical part of establishing a successful cover crop stand.

The results he’s seeing have made Zubke a believer in the practice.

“2014 was the first year I aerial seeded cover crops on my farm,” Zubke said. “I have custom applied covers by air for surrounding growers for about three years.”

Barsness noted that in results he’s tracked from South Dakota in 2012 and 2013, dry fall weather limited the growth of aerial seeded cover crops. He said in 2014, rains in August and September helped to establish the seeds for a good cover.

Residual chemicals

Farmers need to pay attention to what chemicals were used on corn and the residual effect that may affect cover crops.

“Make sure you check with your agronomist or chemical representative to see if there are potential residuals for broadleaf or grasses,” Barsness said. “For a lot of herbicides, the residual affect has past after four months. That’s why it’s good to start the process in the spring and choose herbicides that will work with the cover crops that are planned to be planted in the fall.”

Greenhoff, who has been a pilot since 1988, said there was a lot of bug pressure this year that kept him in the air. As he waited for the plane to be loaded for the day, he said he’s been seeding from his planes for several years.

“We use twice the seed as if the crop were drilled into the soil,” Greenhoff said. “We know some will get caught in the swirl or silk. Not all reach the seed will reach the ground. The seed that does grow settles in the middle. After the combine goes through the field, it’s almost like re-seeding, especially if there is moisture. We really saw some pretty fields in Minnesota last year.”

Plan for next year

One step that Barsness suggests is to determine what the next year’s cash crop will be. If this year’s crop is corn and soybeans is planned for next year, then a good choice would be cool season grasses. A second issue is whether or not the crop will need to overwinter for grazing. If it does, it would be good to have a rye or winter wheat as a percentage of the mix. Since these plants continue to grow after the fields are combined, it makes for awesome grazing, Barsness said.

Five to 10 species can be included in the seed mix. Some of the choices include rye, winter wheat, annual rye grass, crimson clover, common vetch, turnip, radish, canola and dwarf essex rapeseed.

Barsness said it’s important to make crop insurance agents aware of what is being done in the fields. Check for any specific requirements or harvest restrictions for cover crops.

In the spring, a chemical burn down would be used before planting as aggressive tillage would disturb the root systems that the crops have established, undoing the benefits of the cover crop.

Financial benefit

For actual soil health benefits, Barsness said it’s hard to estimate the rate of return on the dollar amount.

“I’d suggest trying a couple of fields an evaluate field health, especially on highly erodible land,” Barsness said.

It costs roughly about $10 an acre for the plane to apply the seed. Zubke said that seed can vary depending on the mix, probably $8 per acre to $25 per acre on the higher end.

NRCS provides cost share programs that may be used for establishing cover crops. Included are EQIP which provides payments to eligible producers to help implement approved conservation practices on eligible land. The Conservation Stewardship Program helps agricultural producers maintain and improve their existing conservation systems. Aerial seeding of cover crops is used mostly in eastern South Dakota. NRCS offices keep a list of names of pilots available to do the seeding.

Barsness said time is needed to do the paperwork, and if producers are interested, they need to sign up this fall if they want to seed next year. Check with NRCS staff for help in figuring out what’s right for the soil in your fields.

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