Study: Corn takes up most of its N naturally

Jun 15, 2023

Corn growers seeking to increase the amount of nitrogen taken up by their crop can adjust many aspects of fertilizer application, but recent studies from the University of Illinois Urbana-Champaign show those tweaks don’t do much to improve uptake efficiency from fertilizer.

That’s because, the studies show, corn takes up the majority of its nitrogen — about 67% on average — from sources occurring naturally in soil, not from fertilizer, according to a university news release.

The evidence for soil as corn’s major nitrogen source came repeatedly over the course of four studies, the first published in 2019 and the rest more recently.

In all four studies, researchers in the Department of Natural Resources and Environmental Sciences in the College of Agricultural, Consumer and Environmental Sciences at University of Illinois labeled fertilizers with a naturally occurring isotope of nitrogen, known as 15N, and applied it in the field at different rates, forms, placements and timings.

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Video: Dr. Emerson Nafziger: Nitrogen Fertilizer Rates for Corn

The Crop Science Podcast Show, Dr. Emerson Nafziger from the University of Illinois breaks down decades of nitrogen research. From the evolution of N rate guidelines to how soil health and hybrid genetics influence nitrogen use efficiency, this conversation unpacks the science behind smarter fertilization. Improving how we set nitrogen fertilizer rates for rainfed corn is a key focus. Discover why the MRTN model matters more than ever, and how shifting mindsets and better data can boost yields and environmental outcomes. Tune in now on all major platforms!

"The nitrogen that comes from soil mineralization is the first nitrogen the plant sees, and its role is underestimated."

Meet the guest:

Dr. Emerson Nafziger is Professor Emeritus of Crop Sciences at the University of Illinois at Urbana-Champaign, with degrees in agronomy from Ohio State, Purdue, and Illinois. His research has focused on nitrogen rate strategies and crop productivity. He co-developed the Maximum Return to Nitrogen (MRTN) model, which is widely used across the Midwest. His research spans N response trials, hybrid interactions, crop rotation effects, and yield stability.