Soybeans could work as a rotating crop and help prevent weeds

Soybeans are in just about everything from cooking oils and fuel to tofu, candy bars and crayons. They are grown just about everywhere — except the Big Horn Basin.

But that could change following some experimental planting at the University of Wyoming Powell Research and Extension Center and on some privately-owned farms across the state.

On Tuesday, UW researchers and specialists spoke with some Wyoming farmers about how soybeans can help control weeds and possibly function as a cash crop.

There currently are six soybean maturity groups planted in 22-inch rows in the research center’s trial fields north of Powell, and results have varied depending on the type of soybean planted.

“The goal is to provide answers,” said Gustavo Sbatella, assistant professor of irrigated crop and weed management through the University of Wyoming. “Had this been a failure, it would be on us.”

The research facility plants different crops to figure out what works in the area so local farmers don’t have to risk a failed harvest, Sbatella said.

“We don’t want them to think they are stuck with barley and sugar beets,” Sbatella said. “The way I see it is, if someone is doing dry beans with nightshade problems, then maybe they could do soybeans to clean up the field.”

It would take two rotations of soybeans for a field to be cleared up, he said. By rotating different crops, it changes the composition of the soil and bringing soybeans into rotation is a possible route for lowering that amount of nightshade weeds in fields.

It’s unlikely that soybeans will replace the current top crops for the region, but it could be an option for farmers with nightshade issues.

“I don’t see this becoming a soybean region,” said UW Extension educator Jeremiah Vardiman.

Mike Baker of Thermopolis is in his second year of trying out soybeans, having planted six acres last year and 12 this year with seeds from Syngenta AG.

“I was told the air is too dry for soybeans, but I would say four-bean pods is pretty darn good,” Baker said.

Soybeans can be used for bio diesel, and some companies will contract for that, Sbatella said.

 “But, that goes with the price of oil,” Sbatella said.

 It might be a few years before soybeans start showing up at Big Horn Basin’s farms, said John Tanaka, associate director for the Wyoming Agriculture Experiment Station and director for the Powell station.

There were a lot of questions about the possibility of raising soybeans in the area during last winter’s listening session, Sbatella said.

“The interest was mainly by people planting dry beans with nightshade problems,” Sbatella said.

Nightshade has become such a big concern for Big Horn Basin farmers that some were thinking about not planting dry beans anymore, so they were seeking an alternative rotation crop, Sbatella said.

Dry beans are basically the only legume grown in the region and are a necessary component to keeping local fields healthy and productive.

Soybeans would function well as a rotation crop with grass-type plants such as corn or barley, Sbatella said.

This is where the UW fields come into play, as they also find out what variety works best and under which conditions.

An unusual factor for soybean growth is flowering is triggered by the amount of light the plants receive, so they are grouped into categories based on how much light is necessary for a successful harvest — this is called a photoperiod.

Basically, these groups are based on latitude, since the days are about 12 hours long near the equator and several hours longer in parts of Canada or South America — and soybeans are grown everywhere, including Sbatella’s home country of Argentina.

UW’s trial planting of soybeans is just a maturity group trial this year, because all of their seeds came through Asgrow, Sbatella said. It’s possible other seed companies could get involved so that a variety trial can be conducted.

“The trick, and what is a problem, is, if you don’t get the right photoperiod, it will flower too early and you will have a tiny plant,” Sbatella said. “This is all about learning our day length.”

The amount of darkness also is a factor, Baker said, noting that Syngenta told him that if a series of lights were set up nearby, the soybeans would never mature.  Hawaiian soybean growers even go so far as to provide supplemental artificial lighting, Sbatella said.

“That seems like an expensive way to do business,” Vardiman said.

As for the local trials, Sbatella said there are some very different responses that he was not expecting.

Four different agronomists could not agree on what is coming out of the ground. But, it appears as though the soybeans are reacting differently due to the soil’s pH levels, Sbatella said.

“They told me these soybeans have never seen such a high pH,” Sbatella said, noting that local pH levels are almost always above seven.

“We need to find lines (of soybean varieties) that tolerate the pH we have here,” Baker said. “Day length and elevation are factors too, it is a puzzle — a fun puzzle.”

Baker said he planted on May 22, and the soybeans took so long to sprout that he thought they were dead, but they came up in mid-June.

About 140,000 plants per acre were planted on June 8 in one of UW’s trial fields, and two shots of Roundup were applied with a second round of it mixed with Outlook as the only means of weed control.

Roundup is a cheap method for weed control that comes with risks, Sbatella said. If a farmer uses it on corn or sugar beets, then applies it onto their rotation crop, and continues on, it would be possible to have 15 applications of Roundup on the same field in a three-year period. This means selective pressure on weeds, and that’s something farmers want to avoid for healthy and productive fields.

As for irrigation, the trial fields used the same method of flooding that’s common in the Basin about every two weeks until maturity, then it was switched to every 7-10 days, said Powell Research and Extension Center Farm Manager Camby Reynolds.

Soybeans are self-pollenating, but like many crops, they need some fertilizer; so UW’s trial fields all received applications of nitrogen and phosphorous.

Once soybeans are brought into rotation, it won’t be necessary to inoculate the fields, since there should be enough bacteria present at that point, Sbatella said. But, the first few times around will require some inoculation for the bacteria that promotes plant growth.  

When it’s time to harvest, UW’s combine will be used on the same setting as with wheat, Sbatella said.