What is the best grain rotation for your area of the Mid-South? An ongoing, wide-ranging study is searching for answers.

At the recent Tri-State Soybean Meeting in Stoneville, Miss., Bobby Golden explained the project. “You might not be aware that we’re investigating grain rotations in the Mid-South,” said Golden, an assistant professor with Plant and Soil Sciences at Mississippi State University.

In the last 10 to 12 years as more corn has come into the Mid-South, what is happening to soybean yields? “We began looking around and decided there wasn’t a lot of long-term rotational data in the region. Wayne does have a long-term study but it’s cotton based. We don’t have a study that’s grain based.”

Now in its second year, Golden hopes the project “will go for another six or seven years so we can get at least two rotation cycles.

“One of my biggest concerns and what got me excited about – and something many (producers) here do – is the burning of corn stubble. For the last three or four years, especially where corn stubble is burned, is we’re beginning to see issues with soybeans and sulfur.

“We no longer get free sulfur out of the atmosphere since we cleaned up after the Environmental Protection Act in the early 1970s. We do a really good job of putting sulfur on our corn.”

That isn’t always the case with soybeans. “The whole slant we put on the project is: if we grow corn and grain sorghum in rotation with soybean, what does it do to yields.”

Setup

There are 12 base treatments that range from continuous corn and soybeans to one-to-one rotations with corn and soybeans to two-to-one rotations going both ways. “We also have dryland sorghum and a three-way double-crop system rotation.

“They’re split by residue management techniques. So, for every test we’ll have a burn side and a non-burn side. Obviously we don’t burn soybean stubble when soybeans are in the rotation – only the grain sorghum and corn stubble.”

There are still high-intensity burning areas. “Some guys have that old cotton mentality of no stubble being left out. We’re losing a lot of sulfur. If you’re burning corn or sorghum stubble, you’re losing 75 percent of the sulfur that was taken up into that straw, not counting what was taken up in the grain. That can’t help but impact our soybean yields in the long run.”

All the soybeans grown in the project are Group 4s.