South Dakota State University looks at growing rye for biomass as part of corn, soybean rotation, which would allow producers to harvest three crops instead of two during two growing seasons

Graziela Medina Shepnick

BROOKINGS, South Dakota , August 15, 2011 (press release) – A new research project at South Dakota State University looks at growing rye for biomass as part a corn and soybean rotation.

A key advantage is that producers in states such as South Dakota could harvest three crops instead of two during two growing seasons.

Principal investigator Peter Sexton, an associate professor in sustainable cropping systems for the SDSU Cooperative Extension Service, said the winter rye would be sown in the fall on land that raised corn the first year, then harvested at about the end of May the following year. By not letting the rye form grain but instead harvesting the leaves and stems — the fibrous “biomass” that can be made into next-generation biofuels — producers will have enough time to seed soybeans immediately afterward for harvest later that fall.

“The idea isn’t to have a seed crop from the rye, the idea is to produce biomass. Basically we’re going to let the rye grow until it finishes its vegetative growth and switches over to reproductive growth. At that time we’ll take it for biomass. It could be taken for forage also,” Sexton said. “That should happen in late May. So we should be able to plant the beans the very end of May or first week of June. That’s enough time to make a bean crop.”

So in two years, producers could harvest corn, rye grown for biomass, and soybeans. Or alternately, they might harvest soybeans, rye for biomass, and soybeans again.

The study is one of four alternative energy projects for which the North Central Sun Grant Center at South Dakota State University has recommending federal funding. The U.S. Department of Energy must give final approval before the projects are implemented.

The project is designated to receive $269,917 in funds through the North Central Sun Grant Center, while SDSU is contributing $66,935 toward the project.

The priority area for this request, as identified by the North Central Sun Grant Center and the U.S. Department of Energy, is production systems that optimize biomass feedstock yield and economic return across a diverse landscape in the North Central Sun Grant Region while
minimizing negative effects on the environment and food/feed production. Biomass feedstocks of interest include woody and herbaceous crops suitable for commercial production in the region and annual crop residues.

“It’s not a system that needs some new technology in order to function. It can be done with what we have,” Sexton said. “You might have to live with a little delay in planting date, but you have the benefit of a good rotation crop with soybeans. You may come out with pretty good yields.”

This summer’s preliminary field work — done by producer Ben Culver of rural Brookings, S.D., in cooperation with SDSU plant breeder Lon Hall — already has demonstrated that there’s enough time to plant soybeans after the rye reaches the stage at which it would normally be harvested for biomass.

The SDSU study will continue through March 2014. It will evaluate a winter rye variety developed by SDSU plant breeder Lon Hall as a potential biomass crop, along with some other rye varieties.

Rye will be grown in corn and soybean rotations at Watertown and Beresford in South Dakota, and at Carbondale in southern Illinois.

In southern Illinois, two rye varieties will be drilled in following corn of 110 days relative maturity. Soybeans will be established following rye harvest and yield determined for each plot.

“A lot of this is just quantifying the various effects,” Sexton said. “We know we can get the winter rye in after the corn, we know we can get the rye out in time to get a soybean crop. We want to get a good grip on what does that mean quantitatively for corn and soybean yields versus the rye biomass yields.”

The study also includes an on-farm evaluation. Replicated test strips not less than 1 acre in size will be established with a cooperating grower in eastern South Dakota to better evaluate costs and obtain data in a production environment.

In 2010 there were an estimated 87 million acres of corn and 78 million acres of soybeans grown in the U.S., Sexton noted. If 10 percent of the land going into soybean used a preceding winter rye cover crop, it would amount to 7.8 million acres. If the winter rye produced 1.5 to 3 tons per acre of biomass, this would produce 11 to 22 million tons of biomass from just 10 percent of the soybean acreage.

In South Dakota, corn varieties of 75, 85, and 95 days relative maturity will be established at an SDSU research farm at Watertown, and varieties of 85, 95, and 105 days relative maturity at an SDSU research farm at Beresford. Rye will be planted by two methods in each: hand broadcasting seed (to simulate aerial seeding) at the late dent stage (50 days after silking); direct seeding immediately after harvest using a no-till drill.

The researchers will develop cost estimates using published enterprise budgets for corn, soybean, and small grain production, along with data obtained from the research trials, particularly the on-farm observation trial. From the study they’ll be able to estimate the breakeven price matrix for this practice based on biomass production as well as corn and soybean yields and prices.

Sexton’s co-principal investigators on the project are assistant professor Michael Miller of the SDSU Department of Economics; plant breeder Lon Hall; and professor Robert Berg, who manages the Southeast Research Farm at Beresford.

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