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ISU Study Finds Nitrogen Leads To Decrease In Biodiversity

WIKICOMMONS / Midewin National Tallgrass Prairie

Farmers use fertilizer because it helps crops grow. But according to a new study from Iowa State University, for some native plant species in Iowa a chemical found in fertilizer does the opposite, harming the biodiversity in Iowa’s tallgrass prairies.

Nitrogen is found in fertilizer and is hard to contain as it flows from farm fields to water and gets into the air, reaching other plants.

To see how this substance affects naturally occurring species, ISU researcher Lori Biederman put fertilizer on plots of tallgrass prairie. This caused brome, an invasive grass species, to "go bananas" and grow so much that native plants were crowded out. 

It's not that brome reacts more strongly to nitrogen, but rather because it blooms months earlier than native species it prevented other species from flourishing. 

"So there’s fewer spaces available for other organisms to come in," she explains. "Because it can get taller and put out more leaf tissue before anyone else can get it up, then it can gather more sunlight, more energy, and that means it can get bigger again."

Biederman notes that because native species have deeper roots these plants are better for the soil. This research was published in the science journal PLOS One.