Longer Rotation Can Improve Production

Published online: Sep 07, 2017 Feature Alexa Althoff
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It’s been said that two’s company, but three’s a crowd. While this old aphorism may be true in some circumstances, it fails to hold as much water in regards to irrigated crop rotation in sugarbeet fields.

Bart Stevens, an irrigated systems research agronomist and research leader at the USDA-ARS Northern Plains Agricultural Research Laboratory in Sidney, Mont., has been studying a three-year crop rotation system alongside a number of other experts. With the aid of Montana State University and North Dakota State University, a number of inquiring minds began investigating the possibility of rotating sugarbeets with soybeans for the last decade.

“We have started to refer to ourselves, the three entities, as The MonDak Research Triangle,” says Stevens. “Our interest in pursuing this a number of years ago was to try and diversify our sugarbeet production system and the rotations we use.”

While the two-year rotation has historically been the premier method, for sugarbeet production, Stevens notes that science is now pointing toward a number of benefits that can be gained by adding soybeans to that rotation.

“Making it a three-year rotation rather than a two-year rotation would benefit the soil because soybean is a different kind of crop and it encourages different types of micro-organisms to grow,” he says.

Soil health is an obvious bonus to a prolonged rotation, but there’s an additional benefit when it comes time to grow sugarbeets once more. Research has found that a three-year rotation with soybeans can actually increase sugar yields, which are approximately 10 percent higher.

When Stevens talks about soybeans, though, he’s not referring to your grandfather’s soybeans. Great strides in genetics have allowed certain varieties of the crop to adapt to Montana’s shorter growing season. Though the issue of colder weather has been mitigated, Stevens says irrigated fields continue to be the best bet for soybeans. “Soybeans are probably not well-adapted to drylands,” Stevens says. “They are a full-season crop. They grow into September, and typically our rainfall runs out before then.”

While genetic improvement has been happening more recently, this newcomer also actually has a very old—and very nifty—trick.

“Soybeans are a unique crop because it takes nitrogen from the atmosphere and converts it into a form that plants can use,” says Stevens. “The atmosphere is 79 percent nitrogen, but that’s in a form the plant cannot use. The soybean can convert that into a plant-usable form.”

The consistent market price of soybeans also proves attractive to growers, as does the lack of need to purchase new equipment. With the myriad of positive benefits from adding soybeans to a current rotation, there’s bound to be some challenges, and there are.

“Rhizoctonia causes the root and the crown to rot in the field, and that’s not good,” says Stevens. “It actually doesn’t do much damage to the soybeans at all, but soybeans are a host so they can keep that population of the disease organism alive and well in the soil. In the last seven years we did not see an increase of that disease in our sugarbeets, but that’s something farmers should watch closely.”

Weed control can be another issue, but Stevens says these potential pitfalls can be avoided with proper care and the correct application of certain chemicals. To find out more information on integrating soybeans into a three-year crop rotation of irrigated sugarbeet fields, growers are encouraged contact the USDA-ARS facility in Sidney, Mont.


Source: RoundupWeb