Variable Rate Nitrogen Application Saves Money & the Environment

Gary Roberson, Associate Professor and Extension Specialist with the Department of Biological and Agricultural Engineering at NC State University was a presenter at Tuesday's Precision Ag Field Day at the Tidewater Research & Extension Center.
Roberson explains that variable rate nitrogen application is not only cost effective, but environmentally friendly, as well. Technology such as this is extra important in a year following a drought, according to Roberson:

“Yes it is, we saw our yield numbers all over the board last year, nitrogen usage obviously tracks with the weather, and soil types, and soil conditions and everything else. What we’ve seen in some of our cases we’re coming in behind a dry year, is that nitrogen that was put out last year might still be available, so with the sensor-based technologies we’re taking advantage of that, and hopefully being more efficient with the way we use nitrogen all together. So, it’s an exciting piece of technology and we’ve got a lot we can learn from it.”

Well, nitrogen is expensive, and we don’t want to overuse it if we can help it.

“Absolutely, it’s an expensive commodity, and also from an environmental standpoint something that can contribute to some serious issues. So, if we can present a technology that help the farmer be more cost effective and more environmentally responsible, I think we’ve got a winner.”

Now, let me ask you this, I noticed on the highway driving in, we’ve got some corn fields I like to call ‘friendly’…they’re wavy. They’re tall, they’re short, their yellow, all in the same field. Is that a result of nitrogen left in the field from the drought last year?

“It’s hard to say, I mean not knowing the history of the field, it could be a reaction to the drought last year, it could be a machinery problem this year. Application of fertilizer this year might not be as uniform as the farmer would like, so it’s difficult to say. There’s a lot of factors that go into a case like that, and we really have to…you have to dissect it, take it apart layer by layer and see what’s really happened out there.”

Now, are you finding that farmers are embracing these new technologies, or are just sticking a toe in the water and seeing?

“We’re seeing pretty much a broad mix. I’ve got some people that are contacting me that are really anxious to dive into it, they want to acquire as much technology as they can quickly. Others, are little bit more timid, like you said, they’re willing to put their toe in the water. What I advocate for any farmer in any situation, is to pick the technology that seems to be the best fit first, the thing that’s going to have the best potential for a pay back. Get comfortable with that and then build on it.

Might be soil sampling, it might be field scouting, it might be yield monitoring, it might be swap guidance, whatever. Pick a starting point, get comfortable with it, and then lets build on it.”

Alright, is there anything you’d like to add?

“I think a field day like this is a great opportunity for us to present what’s going on, to entertain questions from our farmers, interact with them in a setting like this. It’s great.”

For more information from the Precision Ag Day, check out our coverage here. is dedicated to serving the agricultural industry in the Carolinas and Virginia with the latest ag news, exclusive regional weather station readings, and key crop market information. The website is a companion of the Southern Farm Network, provider of daily agricultural radio programming to the Carolinas since 1974. presents radio programs, interviews and news relevant to crop and livestock production and research throughout the mid-Atlantic agricultural community.