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Corn+Soybean Digest

Risky Business Or Good Business?

Greg Anderson follows a soybean production practice that might, in some people's view, fall into the category of, “Don't try this at home.”

He will be planting his 19th continuous soybean crop this spring on his dryland farm near Newman Grove in northeast Nebraska. Ninety-five percent of his row-crop acres are in continuous soybeans.

“I'll be the first to say that it's not for everybody,” says Anderson, immediate-past chairman of the United Soybean Board and dedicated promoter of the crop.

But it's economic rationale, not unchecked enthusiasm for soybeans, that keeps him planting them year after year. “If we get 45 bu./acre or better, we're competing with anything I could do with corn — and certainly this season with high fertilizer and diesel fuel costs,” he says.

He lists several other economic factors that favor continuous soybeans over a corn-soybean rotation on his farm:

  • No dryer and drying costs, which corn requires most years.
  • Less trucking volume vs. corn.
  • No corn head to own.
  • No special planting equipment

A conventional drill with double-disk openers on 10-in. row spacing can handle planting no-till into soybean residue.

Maybe more of a personal preference than an economic point, soybeans let him harvest sooner than is possible with corn — most years.

When it comes to continuous soybeans, “It's not usually recommended,” says Jim Specht, University of Nebraska agronomist. “But some people, like Anderson, have made it work.”

Soybeans usually enjoy a yield boost in a corn-soybean rotation, which is attributed to soybeans capitalizing on the nitrogen fertilizer applied for corn, says Specht. Also, some might see a bit more economic risk with continuous soybeans versus a crop rotation, because you have just one crop to sell.

Also, when you're growing the same crop year after year, you can have a buildup of diseases, such as phytophthora and soybean cyst nematode (SCN), he adds.

On the other hand, Specht recognizes some of the economic pluses in Anderson's continuous soybeans: Soybeans represent lower input outlays than does corn, owing to lower seed, fertilizer and energy costs for the beans.

During the 18 years

Anderson has grown continuous soybeans on his rolling land of mostly clay loam soils, yields have shown no downward trend. They've averaged 45-bu. or better long term. Much of the land he farms is highly erodible.

“I'll be the first to go back to it (a corn/soybean rotation), if it stops working,” Anderson says. “The reason I'm getting by with this so well is because of where I live. We're not cool and damp very long. In fact, we often fight hot and dry conditions.”

Diseases such as white mold and sudden death syndrome haven't been a problem, he says, “Knock on wood.” He does watch soybean variety choices for phytophthora resistance, especially on bottomland. “I do rotate varieties,” he adds.

SCN hasn't been a problem, either. He has tested for it, and has tried SCN-resistant soybeans only to experience a “little yield drag,” which leads him to believe SCN isn't a problem in his fields.

If there is a disease or insect problem, he'll be among the first to have it, Anderson says. He did have a soybean aphid infestation for the first time in 2004, but had no problems with them last year.

Bean leaf beetles are a problem for him, especially on early planted beans. And he likes to plant early to take advantage of optimum daylight periods for critical growth stages.

A newer insecticide seed treatment, Cruiser, which he tried last year, proved effective against that insect. Beans came up uniformly with no shot holes, displaying picture-perfect leaves, he says. He got early and late bean leaf beetle control from that treatment. His seed treatment includes a fungicide.

Other producers have grown continuous soybeans successfully, he notes, including a friend in northeast Kansas who had done it for 15 years in the 1980s, without experiencing any downward yield trend.

Anderson and his father began drilling soybeans in 1983, before the advent of Roundup Ready soybeans, and had good weed control from Treflan, with a 2,4-D burndown ahead of planting some years.

When Roundup came along in the 1990s, growing no-till beans-after-beans became easier, according to Anderson. “That's probably kept us growing continuous soybeans.” He still finds a burndown with 2,4-D necessary some years. Weed control ahead of planting and no-till are a good combination for preserving soil moisture.

His standard practice is tandem applications of Roundup WeatherMAX to stop both early and late-emerging weeds. To date, according to Anderson, he has seen no weed resistance to Roundup.

Incidentally, the milkweed and cockleburs that were among the problem weeds under his corn-soybean rotation have mostly gone away.

He soil tests every year with recommendations based on a 50-bu. yield goal. Results come back generally calling for 30-40 lbs. of phosphorus per acre, which he broadcasts in the fall. Occasionally, zinc and a couple of other micronutrients are recommended. And, some fields need lime. Nitrogen is rarely called for. Some soil tests have come back indicating no applied nutrients are needed.

“In these years when fertilizer and other input costs are so high, the biggest cost I have is seed,” Anderson says.

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