Seeking an Edge

Jarett C. Bies, AgBio Communications

USDA researcher and SDSU faculty member Shannon Osbourne, left, and SDSU graduate student Ann Weinkauff are conducting research that should help South Dakota wheat growers. Part of that research involves a Greenseeker (pictured), an instrument that calibrates the nitrogen content in crops.

SDSU students working to help South Dakota wheat producers

The efforts of a South Dakota State University graduate research assistant may determine whether an idea that bubbled up during a conversation between SDSU scientists will pay off with results for South Dakota wheat producers.

Using an instrument that has been used to calibrate the nitrogen content in crops in southern states, Ann Weinkauf, a native of Pipestone, Minn., is seeking a critical value indicator for nitrogen application to increase spring wheat protein in South Dakota.

“Farmers get paid a premium for high-protein wheat, and in order to efficiently obtain high-protein wheat, you may need to apply nitrogen at flowering,” said Weinkauf, who seeks to discover the moment that spring wheat can most use a nitrogen application.

“Some of the crop consultants currently have this instrument (the NTech GreenSeeker) to look at nitrogen status in-season,” said Shannon Osborne, an adjunct faculty member with the Plant Science Department at SDSU and a research agronomist with the U.S. Department of Agriculture’s Agricultural Research Station Laboratory, Brookings. “If they already have this instrument, they could utilize the technology to help the producer further manage his crop.”

Osborne was discussing new technology with Ron Gelderman, manager of the SDSU Soil and Plant Analysis Service Laboratory, when the idea that led to Weinkauf’s project came to light.

“We needed some kind of indicator to determine when the producer would get a protein response to nitrogen and when not,” Gelderman said. “That’s where Shannon and I both realized that [the GreenSeeker] might provide the indicator we needed.”

Using red and infrared energy, the GreenSeeker can calculate a “normalized difference vegetative index,” which is an estimate of biomass and nitrogen content in a number of crops, including spring wheat. The study of spring wheat’s index, then, should lead to a critical value, and that should lead to precise nitrogen application—and adding nitrogen with such precision would make a big difference, Weinkauf said.

The theory tested, technology expanded
Weinkauf’s first task as she took over the project with Osborne was to analyze data collected in 2003 and 2004, developing a database that would lead to the critical value the researchers needed. Weinkauf found the value range and began testing it.

“With the help of funding from the South Dakota Wheat Commission, we set up locations throughout central South Dakota,” she said. “We set up plots with different nitrogen rates at the beginning of the season, and nitrogen was applied at planting at different rates.”

Scanning at three different growth stages, Osborne and Weinkauf were able to gather more data, further focusing their critical value findings.
Drought conditions reduced the data collection in 2006. “Last year was difficult,” said Weinkauf. “I didn’t have very good wheat to work with. This year we’ll get more data in and refine the critical value.”

Osborne said a next step would include testing the critical value in different environments in other parts of the state.
The more data the better, said Weinkauf. “We need more data and locations,” she said. “It’s on the right track, and, in the next few years, it will be something that could be beneficial for a grower.”

Gelderman said the discovery of the critical protein level could lead to improvements in on-the-go application. “If we do find a reliable critical level, then these sensors could be used in the field to determine where nitrogen should be applied or not be applied. It would basically be an on-off application,” he said. “The preliminary data looks pretty good, and we’re hopeful about having an indicator that can tell us when to apply nitrogen to raise grain protein levels.”

Weinkauf is now crunching the numbers on the harvested wheat, fine-tuning the data. She says she’s confident she’ll add another effective tool to the producers’ arsenal. “The plots that got foliar (on leaf) nitrogen always had higher protein than the ones that did not,” she said. “That’s what we expected. We’re right on track.”

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Seeking an Edge