Farm and Field

Improving detection of early-season corn nitrogen stress

Posted: Jan. 26, 2020 12:01 am

Deciding when and how much nitrogen fertilizer to apply is a perennial challenge for corn farmers.

Scientists at the University of Illinois have shown that nanosatellites known as CubeSats can detect nitrogen stress early in the season, potentially giving farmers a chance to plan in-season nitrogen fertilizer applications and alleviate nutrient stress for crops.

"Using this technology, we can possibly see the nitrogen stress early on, before tasseling. That means farmers won't need to wait until the end of the season to see the impact of their nitrogen application decisions," said Kaiyu Guan, assistant professor in the Department of Natural Resources and Environmental Sciences and professor at the National Center for Supercomputing Applications.

CubeSats bridge the gap between existing satellite technology and drones. With more than 100 of the relatively tiny satellites currently in orbit, "CubeSats get down to a 3-meter resolution and revisit the same location every few days," Guan said. "So, right now we can monitor crop nitrogen status in real time for a much broader area than drones."

Guan and his collaborators tested the capabilities of both drones and CubeSats to detect changes in corn chlorophyll content, a proxy for the plant's nitrogen status, and focused on an experimental field in Central Illinois during 2017.

"The idea was to see how much effect timing and form of nitrogen fertilizer would have on yield. This study allows an evaluation of how well the imaging could capture yield responses to nitrogen applied at different rates and times," said Emerson Nafziger, professor emeritus in the Department of Crop Sciences and co-author of the study.

The scientists compared images from drones and CubeSats, and their signals matched well with tissue nitrogen measurements taken from leaves in the field on a weekly basis. Both technologies were able to detect changes in chlorophyll contents with a similar degree of accuracy and at the same point in the season.

"This information generates timely and actionable insights related to nitrogen stress, and so could provide guidance for additional nitrogen application where it's needed," Guan said.

Soybean production

Illinois continues to top the annual crop production report estimate for soybean production.

Despite a tough growing season for most of the Midwest in 2019, Illinois farmers consistently produced strong soybean yields.

Illinois farmers raised 532.4 million bushels of soybeans in 2019 on 9.86 million harvested acres, with an average yield of 54 bushels per acre. Iowa ranked second with 501.6 million bushels raised on 9.120 million acres.

"I won't say it was easy because 2019 will be remembered as the most challenging growing season on record for many Illinois producers, said Doug Schroeder, a Mahomet soybean farmer and Illinois Soybean Association chairman.

ISA Production and Outreach Committee Chairman David Wessel, a soybean farmer from Chandlerville, said ISA's commitment to robust farmer education efforts helps the state maintain its edge.

"Continuing to educate on best practices and new industry innovations makes sure that Illinois growers have a partner in maximizing their yield potential and profitability per acre," Wessel said.

So does a focus on generating worldwide soybean demand.

"One of ISA's key priorities is to create marketplace preference for Illinois soy in export markets, biodiesel, animal agriculture and beyond, said Nebo farmer Roberta Simpson-Dolbeare, who chairs ISA's Marketing Committee. "In 2020, you will see continued focus on nurturing existing markets and opening new."