Rotation Can Make You Richer

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.

Dr. Bart Stevens, Irrigated Systems Research Agronomist/Research Leader at the USDA-ARS Northern Plains Agricultural Research Laboratory in Sidney, 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," Stevens said. "Our interest in pursuing this a number of years ago was to try and diversify our sugar beet production system and the rotations we use."

While the two-year rotation has historically been the premier method, Stevens notes that science is now pointing towards a number of benefits which 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," Stevens said.

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% higher.

Although, when Stevens talks about soybeans, he's not referring to your grandfathers soybeans. Great strides in genetics have allowed certain varieties of the crop to adapt to the shorter growing season of this area. Though the issue of colder weather has been mitigated, Stevens notes irrigated fields continue to be the best bet for soybeans. "Soybeans are probably not well adapted to drylands," Stevens said. "They are a full season crop. They grow into September, and typically our rainfall runs out before then."

While the 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," Stevens said. "The atmosphere is 79% 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 farmers, 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," Stevens said. "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 7 years we did not see an increase of that disease in our sugar beets, but that's something farmers should watch closely."

Weed control can be another issue, but Stevens notes 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, contact the USDA-ARS facility in Sidney.