“By improving nitrogen efficiency in corn production — whether that’s through new varieties or new management strategies for nitrogen applications — we can reduce the amount of unused nitrogen that makes its way into the environment and reduce the amount of fertilizer farmers need to buy,” Rellán-Álvarez says.
Finding Efficiencies
Rellán-Álvarez is part of a multi-state, multi-university project called CERCA (Circular Economy that Reimagines Corn Agriculture) headed by the U.S. Department of Agriculture’s Agricultural Research Service. The Foundation for Food & Agriculture has also joined the effort, providing $4.5 million in grant funding to help the coalition develop new varieties that will allow corn to be planted earlier in the growing season.
Most farmers apply nitrogen fertilizer in the fall at the end of the season for logistical and economic reasons. Rellán-Álvarez says this fertilizer can be lost in the spring due to microbial activity if a crop is not planted early enough to start using the fertilizer for what it was originally intended: growing a crop. That’s where new varieties bred for early planting could help.
A second prong of the project looks at reducing protein in corn, which would require less nitrogen in the kernels. Lower protein within the corn could also support the plant’s ability to return unused nitrogen to the soil, where it could be harnessed for the next growing season.
“Around 40% of corn in the U.S. goes into making bioethanol, which goes into gasoline, but we use corn to make bioethanol because of its starch, not its protein,” says Rellán-Álvarez. “The other major destination of corn production in the U.S. is to feed animals. Corn is probably the best source of starch for animal feed, but corn is not the best source of protein for animal feed because it lacks some essential amino acids, and animal producers increasingly prefer other sources of protein such as soy or an amino acid supplement.
“Taking all that into consideration gives you quite a bit of freedom to reduce protein in corn kernels, which automatically creates nitrogen efficiency,” he adds.
Joseph Gage, an assistant professor in the Department of Crop and Soil Sciences, and Jim Holland, a Raleigh-based researcher with the USDA’s Agricultural Research Service, are assisting with the CERCA research. Holland is targeting ways to decrease protein in corn kernels by investigating how the grain and nitrogen interact. Gage, whose expertise includes developing more resilient crop varieties through genome sequencing, is helping study cold tolerance in corn.
“We have done drone imaging using thermal sensors and multispectral sensors to characterize how the plants are growing under cold conditions and without nitrogen,” Gage says. “The idea is to look for differences in plant traits and also look at the degree to which different genes are turned on or off or up and down in response to nitrogen as well as due to genome sequence differences.”
The goal is to identify genome sequences in commercial corn and its wild relatives that relate to cold tolerance and nitrogen use. Wild corn is better adapted to growing in colder temperatures and less fertile soil, so sequencing the genes underlying those traits could open the door to a new kind of commercial corn.
Redomesticating Wild Maize
A new project in development with the University of Illinois, Urbana-Champaign, will bring together six CALS and N.C. PSI faculty to improve nitrogen efficiency in corn by integrating traits from wild maize and developing better management practices. The project is part of a larger initiative funded through a grant by the U.S. Department of Energy Advanced Research Projects Agency-Energy (ARPA-E).
As part of the project, Rellán-Álvarez and Gage will expand their work on the genetics and genome sequences of commercial and wild corn to assist in designing a new variety. The project also taps the expertise of Alex Woodley and Debjani Sihi, from the Department of Crop and Soil Sciences, whose research focuses on the nitrogen cycle and soil management practices. It also builds on momentum from another of Woodley’s projects investigating the use of synthetic nitrification inhibitors to stem nitrogen waste from crop production.
Christine Hawkes, an ecologist in the Department of Plant and Microbial Biology, will collaborate on the project to address how root fungi can improve corn’s ability to access and absorb nutrients from the soil, such as nitrogen.
“By stacking different approaches to management with genetic methods, our goal is to help increase the efficiency of the plant’s ability to get that nitrogen from the soil into its plant material while also reducing nitrogen losses from the ecosystem,” Hawkes says.
Michael Hyman, also from Plant and Microbial Biology, will develop testing methods to measure the activity of key microbial enzymes in nitrogen production. This technology will be used with other approaches developed by Woodley and Jack Cahill at the Oak Ridge National Laboratory to evaluate the effect of different plant varieties in the production of compounds that block nitrification processes.
The combination of a new nitrogen-efficient variety of corn along with the fungi and synthetic nitrogen inhibitors could create a cleaner, more productive way to grow corn that avoids the need for fertilizer.
Sihi, who holds a dual appointment with Plant and Microbial Biology, hopes these changes will result in farmers spending less on fertilizer and less wasted nitrogen impacting air and water quality.
“It all ties together: We’re not just looking at the gene labels and we’re not just looking at the environmental aspect, but we’re also trying to find an economical solution that saves farmers millions of dollars by coupling lab and field data with process-based models,” Sihi says.
Source : ncsu.edu