Grow cereals with less fertilizer

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Researchers at the University of California, Davis have found a way to reduce the amount of nitrogen fertilizer needed to grow cereals. This discovery could save farmers across the United States billions of dollars a year in fertilizer costs while also benefiting the environment.

The research comes from the lab of Eduardo Blumwald, a prominent professor of plant science, who has found a new way for cereals to capture the nitrogen they need to grow.

This discovery could also help the environment by reducing nitrogen pollution, which can lead to contaminated water resources, increased greenhouse gas emissions and human health problems. The study was published in the journal Plant Biotechnology.

Nitrogen is essential for plant growth and farms depend on chemical fertilizers to increase productivity. But much of what is applied is lost, leaching into soils and groundwater. Blumwald’s research could create a sustainable alternative.

“Nitrogen fertilizers are very, very expensive,” Blumwald said. “Anything you can do to eliminate that cost is important. The problem is money on the one hand, but there are also the harmful effects of nitrogen on the environment.

A new path to natural fertilizers

Blumwald’s research focuses on increasing the conversion of nitrogen gas in the air to ammonium by soil bacteria – a process known as nitrogen fixation.

Legumes such as peanuts and soybeans have root nodules that can use nitrogen-fixing bacteria to supply ammonium to plants. Cereal plants such as rice and wheat do not have this ability and must rely on the uptake of inorganic nitrogen, such as ammonia and nitrate, from fertilizers in the soil.

“If a plant can produce chemicals that allow soil bacteria to fix atmospheric nitrogen gas, we could modify plants to produce more of these chemicals,” Blumwald said. “These chemicals will induce bacterial nitrogen fixation in the soil and plants will utilize the ammonium formed, thereby reducing the amount of fertilizer used.”

Eduardo Blumwald, right, of the Department of Plant Sciences at UC Davis, with postdoctoral researcher Akhilesh Yadav, and rice they and other members of the Blumwald team modified to use nitrogen more efficiently. (Trina Kleist/UC Davis)

Blumwald’s team used chemical screening and genomics to identify compounds in rice plants that enhanced the bacteria’s nitrogen-fixing activity.

Next, they identified the chemical-generating pathways and used gene-editing technology to increase the production of compounds that stimulate biofilm formation. These biofilms contain bacteria that enhance nitrogen conversion. As a result, the nitrogen-fixing activity of bacteria increased, as did the amount of ammonium in the soil for plants.

“Factories are amazing chemical factories,” he said. “What this could do is provide a sustainable alternative farming practice that reduces excessive nitrogen fertilizer use.”

The pathway could also be used by other plants. A patent application on the technique has been filed by the University of California and is pending.

Dawei Yan, Hiromi Tajima, Howard-Yana Shapiro, Reedmond Fong, and Javier Ottaviani of UC Davis contributed to the research paper, as did Lauren Cline of Bayer Crop Science. Ottaviani is also a research associate at Mars Edge.

The research was funded by the Will W. Lester Foundation. Bayer Crop Science supports further research on the subject.

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