When thinking of production practices that go hand-in-hand, soybean and sugarcane may not be the first to come to mind. But growers in south Louisiana look for profit wherever they can find it.

LSU AgCenter weed scientist Al Orgeron is looking at ways to make the combination profitable by adjusting the planting dates of soybeans to allow for the optimal planting dates for sugarcane.

Orgeron wants to find the best planting date for beans to harvest before the optimum time to plant sugarcane, he said.

“USDA research by Dr. Ryan Viator shows that every month we have delays in planting cane beyond August, we lose about 1,000 pounds of sugar per acre,” Orgeron said.

Last year, Orgeron evaluated four soybean planting dates and found the earlier the beans were planted, the better the likelihood of hitting an early August harvest while still seeing good yields.

Orgeron’s team planted early-, mid-, and late-maturity Group IV beans on March 23, which averaged 60 bushels per acre when harvested August 1. That time frame fits into a normal sugarcane planting time frame, Orgeron said.

The second beans were planted on April 7 and yielded 70 bushels at an August 23 harvest. The third planting was April 19, but yields were reduced because of excessive rainfall, and harvest was delayed to the middle of September, he said. A fourth planting on May 6 rotted from excessive rainfall.

“It was a heck of a challenge to harvest soybean experiments in 2016, and the planting of sugarcane was no easier,” Orgeron said.

Variety and weather conditions seem to play a role in the harvest date for the soybeans.

“What we’re trying to do is gather some data on varieties to help sugarcane producers make production decisions,” Orgeron said. “This information is collected throughout the growing season.”

Because of the expense associated with keeping sugarcane fields fallow, including cultivating and spraying, soybeans can be used as a cover crop and potential cash crop, he said.

The idea of double-cropping soybean with sugarcane has caught on throughout the sugarcane-growing area, Orgeron said.

Soybeans are being planted on about half the fallow sugarcane fields of St. James, St. John and Ascension parishes, Orgeron said. About 20 to 25 percent of the 70,000 sugarcane acres in those parishes are fallow each year, and more than 9,000 of those acres are planted with soybeans.

While the same growers may plant soybean and sugarcane, these crops require very different herbicides, he said.

This year, eight Xtend soybean varieties, which are tolerant to the herbicides dicamba and glyphosate, were planted at the Sugarcane Research Station in St. Gabriel along with the current industry standard, Asgrow AG 4232, a variety tolerant of glyphosate but not dicamba, he said.

XtendiMax from Monsanto and Engenia from BASF are two formulations of dicamba that are labeled for use in Xtend soybean systems.

“I had a graduate student who spent two and a half hours cleaning a sugarcane sprayer tank before applying Roundup,” Orgeron said. “Even after triple rinsing and using a commercial detergent, there was still enough of the dicamba left in the lines to cause damage to soybeans that were not dicamba-tolerant.”

Non-dicamba-tolerant soybeans are very sensitive to dicamba. It only takes a minuscule amount — about four drops in the sprayer over an acre — to show symptoms of the herbicide, he said.

“With the results that we are generating, we are able to expand the market and help our producers add to their bottom line,” Orgeron said.

Johnny Morgan