Doug Adams | Humboldt County

by Gary Fandel

Like a lot of Iowa farmers, Humboldt farmer Doug Adams hustled this year to get another crop planted, a cover crop, just before his corn and soybeans were ready for harvest. And like many farmers, he brought in air power to get the job done.

With the harvest workload coming on, finding the time to apply a cover crop before the cash crop is harvested is a challenge. Aerial applications of cover crops are keeping Iowa pilots like Ralph Storm of Webster City very busy.

“I apply mostly a combination of cereal rye, radish and rye grasses,” said Storm. Storm’s plane holds up to 1,600 pounds of seed and covers about 25 acres per flight. “It averages out to about 60 pounds to an acre.”

Q. What water quality practices do you use on your farm? 
A. Adams, a Humboldt County Farm Bureau member, is planting cover crops for the second year, and he’s doubled the acreage from last year.

“Around here, it’s really new,” said Adams, who farms south of Humboldt. “I think it’s really catching on; there’s a lot of interest.”

It’s the same all over Iowa as many more Iowa farmers appear to be making cover crop application an annual practice to improve nutrient management and prevent soil erosion.

It’s all part of how farmers are embracing the Iowa Nutrient Reduction Strategy introduced last November.

Q. Why did you voluntarily adopt these practices?
A. Adams is optimistic and eager to learn more about keeping nutrients in his fields. Adams believes one of the big benefits of cover crops is the prevention of “fallow syndrome,” a buildup of bacteria in the soil.

According to the U.S. Depart­ment of Agriculture, fallow syndrome occurs when land is left unplanted for an entire growing season, causing a loss of beneficial soil fungi required for the plant’s nutrients. Cover crops provide a host source to grow the fungi.

Tilling a fallow field in Hum­boldt County a few weeks ago, Adams was aware of another benefit of cover crops. “They combat weeds.”

Scavenging Nitrogen
Research at Iowa State Uni­versity has proven cover crops reduce nitrate losses. “The biggest, most noticeable benefit of cover crops is holding soil in place and, by default, holding phosphorous in place,” said Mark Licht, field agronomist with Iowa State University Extension.

“There is an added benefit that cover crops scavenge residual soil nitrogen and it keeps that from leaching,” said Licht. Additional benefits include in­­creased organic matter, improved soil structure, improved water infiltration and overall sustained crop productivity, Licht said.

Jeremy Gustafson, a veteran at cover crops with eight years of cover crop experience, has found his skills in high demand this fall for field days as Iowa farmers try to learn more about planting cover crops. “The main reason I’m involved is to control wind and water erosion, to improve the overall soil health,” said Gustafson, who plants cover crops on about one-third of his acres near Boone.

Gustafson, who is also a Boone County Soil and Water Conservation District Commissioner, likes to define good soil structure by the number of earthworms residing. “If you can find up to six earthworms in a cubic foot of soil, then you have great soil.”

Challenge of Planting
The toughest part of planting cover crops is getting them planted in time so they can germinate in the fall. That’s why many farmers have turned to aerial applicators, like Storm.

“Overseeding at the time corn leaves start turning yellow/brown is the best time to seed cereal rye and tillage radishes following corn. Overseeding following soybeans is also a good practice that allows good germination and emergence. Overall seeding time is generally recommended from mid-August to late September,” said Licht.

Cover crops can be seeded later, after the corn or soybeans are harvested, but there’s more risk for establishment of an adequate stand before a killing frost occurs, said Licht.

The average aerial application is about $15 to $20 per acre plus the cost of the seed.

As cover crops have become more popular, numerous organizations are offering information and data, including the U.S. Department of Agriculture, IDALS, Practical Farmers of Iowa and the Iowa Cover Crops Working Group, which is part of the Midwest Cover Crops Council. The Leopold Center for Sustainable Agriculture also provides links to a number of resources.