Should Soybean be Planted before Corn? MU Research Still Favors Corn

Apr 09, 2021

By Linda Geist

In recent years, the agriculture community began discussing whether it makes sense to plant soybean first and delay corn planting.

The University of Missouri Food and Agricultural Policy Research Institute predicts a 7% increase in soybean acres planted in 2021. That leaves farmers wondering whether they could, or should, plant soybean before corn.

Multiyear research at MU’s Bradford Research Center near Columbia still favors corn over soybean for first planting in midwestern corn-soybean rotations, says MU Extension soybean specialist Bill Wiebold.

The research shows the importance of considering the entire crop operation over individual crops or any one component, he says. “If early soybean planting delays corn planting, the productivity of the enterprise could be harmed. Under most circumstances, it makes sense to plant corn before soybean.”

Prior research conducted elsewhere favored early soybean planting but did not examine yields from both crops or look at the effects of delayed corn planting. MU data for both soybean and corn come from the same location, often in the same year. “This allowed us to observe the effects of planting dates on performance of the entire rotation, not just a single component,” Wiebold says.

Researchers looked at data from 12 MU soybean experiments using three and often five planting dates, with the first in late March. Data also give a picture of how weather influenced grain crop yields.

Wiebold planted up to five varieties of high-yield, commercially available soybean with maturity ratings of mid-MG3 to mid-MG4 at a rate of 160,000 seeds per acre.

The corn yield data covers six years with five planting dates beginning in the last week of March. The number of hybrids varied from four to six, with relative corn maturity (RCM) varying from 106 to 114 using a seeding rate of 30,000 kernels per acre.

Soybean and corn were planted into crop residue in a typical rotation with 30-inch rows.

Corn yields more bushels per acre than soybean, so researchers compared relative yields to yield responses. Researchers averaged yields for each crop across all experiments.

Yields of both crops decline when planting is delayed. However, corn starts losing yield at least a month earlier than soybean, and corn yields drop quicker than soybean with delayed planting.

For example, 30 days after yields began to decrease, corn went down 13% and soybean dropped about 8%. The rate of yield loss increased so that 10 days later yields dropped 20% for corn and 14% for soybean.

Soybean yield data from the experiments came from March plantings and give a good comparison of the date when yields start to decrease. Corn yields start to decrease when planting begins after April 20. Soybean yields remain unaffected by planting dates in April and only decreased 4% by May 20.

The two crops also respond differently to planting dates in other ways.

Soybean traits make it make it more stable than corn in its response to weather. Soybean also has more opportunity to produce. Wiebold explains that soybean plants flower for 30 or more days while corn plants complete pollen shed in less than 10 days.

Soybean produces yield at nearly every node on the plant, while corn yield is on a single ear. Soybean also produces three to four times as many flowers than are accounted for as pods at harvest, so there is abundant yield backup.

Source : missouri.edu

Video: Can Gene Editing Give Seeds a Stronger Start?

Reagan Reed has a way of describing his research that might make a plant breeder pause.

“I’m the sort of person who likes to break things to understand them,” he says.

What he breaks are genes involved in seed germination. Reed, a Ph.D. candidate at the University of California, Davis, is investigating whether changing those genes can help seeds establish healthy plants under a wider range of conditions.

Reed recently attended the National Association for Plant Breeding meeting in College Station, Texas, as an NAPB Borlaug Scholar. His work speaks to a question that matters well beyond a research lab: what does it take for a seed to get a crop off to a strong start?

A seed that germinates quickly, alongside the others planted with it, spends less time vulnerable to stresses before seedlings become established.

“If you’re able to bridge that gap between germination to stand establishment, then that’s going to give you the highest probability of having a solid yield that year,” Reed says. “There’s a bunch that can go wrong after that, but it maximises your yield from the start, at least.”

Reed works in Dr. Imtiyaz Khanday’s lab at UC Davis, where his research focuses on seed quality in tomatoes and potatoes. He brings an unusual academic background to the work: at Skidmore College, he studied both biology and Latin.

Reed believes that combination prepared him for research. Translating an ancient text means studying each word, weighing its possible meanings and using context to reach the best interpretation. There is rarely a way to know with complete certainty what an author intended. Science, he says, requires a similar willingness to work through uncertainty.

“Attention to detail and comfortability working with uncertainty,” is how he sums up what Latin taught him.

In the lab, uncertainty can produce a surprise. Reed describes changing one gene and seeing little effect. Changing a second gene also appears to do little. Put both changes in the same genetic background, though, and the result can be substantial.

“I break this gene, nothing really happens. I break this other gene, nothing really happens. I combine them into the same genetic background, and now there’s a massive effect,” he says.

Those interactions matter as researchers gain the ability to edit multiple genes at once. They also complicate any simple account of how a trait works: improving a seed may depend on understanding what several genes do together.

For Reed, the question is whether that knowledge could help seeds germinate reliably when conditions are difficult. Some of the genes he studies prevent germination under certain conditions. That response may serve a plant well in one setting while limiting its usefulness in agriculture. He wants to learn what happens when those genes are changed, and whether the result improves establishment.

Yet a discovery that works in a lab still has a long way to travel before it reaches a field. Reed argues that agricultural biotechnology faces an economic challenge as well as a scientific one. New tools can create value for farmers, he says, but developing them requires a way to support the work in an industry where margins can be thin.

His fellowship with Flagship Pioneering gave him a view across AI, agriculture-related work and human health research. It also reinforced the importance of bringing people with different expertise into the same conversation—a benefit of gatherings such as the NAPB meeting.

“You need to have a team of people with different backgrounds who are willing to work together and approach the same problem in different perspectives and different ways,” he says.

That thinking connects the different parts of Reed’s path. Latin taught him to examine details without expecting a perfect answer. Gene editing lets him test what individual genes do—and what happens when their effects combine. Working with people beyond his own field helps him ask what those findings could become.

He came to agriculture because of its reach: the possibility that work by a small group of researchers could eventually make a difference on a much larger scale. His immediate focus is smaller and more precise. He wants to understand what helps a seed get through its first days and become a healthy plant.