The Story of Nitrogen

One spring a few years ago, after a couple long days of taking soil samples and spreading fertilizer, I got in my car and started heading south from my home in Rochester, Minnesota, driving down the famous Highway 61 that winds along the mighty Mississippi River. As I stopped to watch the river flow by, flocks of ducks, pelicans, and cranes wheeling overhead, I thought about the work I'd been doing, the nitrogen fertilizer I'd been spreading.

Science tells us that nitrogen from fields, lawns, combustion engines, and power plants is a fickle thing, easily moving across the landscape, through air and water and soil, creating a cascade of effects that are hard to predict and even harder to control. The river in front of me was part of a vast system carrying hundreds of thousands of tons of nitrogen from the middle of the United States to the Gulf of Mexico every year, where experts tell us it supercharges the system, ultimately leading to large areas where the water gets depleted in oxygen, driving fish and other creatures away.

In my role as an agronomist, I see every day how nitrogen fertilizer boosts the productivity of farm fields, increasing yields of food, fiber, and forage. But that same nitrogen, if it were in a nearby forest, might cause trees to grow faster or to grow weaker and die; in a freshwater lake it might have little effect at all, but in saltwater systems such as the Gulf of Mexico, it might cause a large boost in biological productivity and algae growth that we generally perceive to be negative. Watching the river quietly flow by, I found myself filled with questions: first and foremost, why would the same atom of nitrogen behave so differently, cause such a wide range of effects in various environments? And, could I use that information to become a better agronomist?

Lastly, it made me wonder about a question that drives the curiosity of many of us, as we see the types of plants change while walking through the forest, as we hunt for bass among the lily pads, watch the plants in our yards and gardens grow or die, or try to diagnose some strange condition in our crop fields: Why am I seeing what I'm seeing?

My name is Greg Klinger and I'm an agronomist and educator at the University of Minnesota Extension. Together with my friend and colleague Shane Bugeja, I've spent the last few months interviewing experts in agronomy, biology, nutrient management, and ecology, trying to understand the story of nitrogen, in the hopes of explaining the phenomena we see out in the field, woods, and water. Join us as we explore the different facets of this complex issue.