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What You Should Know About Nitrogen Sensor Issue

Precision panel discusses nitrogen sensing idea.

Tom Bechman 1, Editor, Indiana Prairie Farm

December 13, 2009

3 Min Read

You're going to see promotion of possibly three nitrogen sensors for use in postemergence corn that are geared to helping you decide if you need to add extra nitrogen, or how much extra you should add. Bob Nielsen, Purdue University corn Extension specialist, addressed the issue during questions and answers at the Bi-State Corps Forum held near Covington recently. He was a member on a panel talking about how to make a profit using the tools of precision farming.

Here's the lead-in to the question. GreenSeeker has marketed a technology for some time that uses optic sensors and then tells a computer on-board the application rig how much nitrogen to apply. The company claimed good success using it on wheat in the western U.S., but it has caught on much more slowly in the Corn Belt. Last year Trimble acquired rights to the product. Meanwhile, Ag Leader bought rights to a sensor designed to accomplish the same thing, but which works differently. And Topcon is bringing a third sensor, apparently one they developed themselves, to the market.

For Nielsen, it's not a question of if sensor technology can be used to detect nitrogen differences and be useful in applying more N during the growing season. Neilsen and Jim Camberato, also a Purdue Extension agronomist, have been experimenting with sensors, primarily the type now offered by Ag Leader, for several years. "We're very comfortable that in waist-high corn, we can do a good job of selecting differences in nitrogen and determining which areas ought to receive extra N at that point," he says.

The Purdue pair has proven this to themselves by checking sensor readings on known N rate strips within a field or plot. A high-rate plot where lots of N was applied serves as a reference strip for running the device over the rest of the field. What the sensors are reading is light reflectance, and translating that into an estimate of nitrogen content in corn plants. How they do it differs, but the concept is the same.

The problem is whether of not the same concept works at sidedressing time. While it's not yet totally clear if all three companies with these new products intend to market them for use at sidedressing, it remains a possibility.

"We haven't been successful at picking up differences in nitrogen on younger corn," Nielsen told the audience. "We even tried it on V8 corn, which is at the top edge of what you would want to sidedress. But so far we can't say that we've picked up differences in N that would let us make recommendations at that stage. Later on, at waist high, yes, definitely. But then you're talking coming in and applying that last 50 pounds or so with either high-clearance sprayers or with drops."

Nielsen still sees value for the concept, and will continue studying it. In fact, a graduate student will being a new project next spring, trying to determine at exactly what stage of growth of corn it is possible to detect differences in nitrogen within plants, based on known or applied nitrogen levels.

Stay tuned!

About the Author(s)

Tom Bechman 1

Editor, Indiana Prairie Farm

Tom Bechman is an important cog in the Farm Progress machinery. In addition to serving as editor of Indiana Prairie Farmer, Tom is nationally known for his coverage of Midwest agronomy, conservation, no-till farming, farm management, farm safety, high-tech farming and personal property tax relief. His byline appears monthly in many of the 18 state and regional farm magazines published by Farm Progress.

"I consider it my responsibility and opportunity as a farm magazine editor to supply useful information that will help today's farm families survive and thrive," the veteran editor says.

Tom graduated from Whiteland (Ind.) High School, earned his B.S. in animal science and agricultural education from Purdue University in 1975 and an M.S. in dairy nutrition two years later. He first joined the magazine as a field editor in 1981 after four years as a vocational agriculture teacher.

Tom enjoys interacting with farm families, university specialists and industry leaders, gathering and sifting through loads of information available in agriculture today. "Whenever I find a new idea or a new thought that could either improve someone's life or their income, I consider it a personal challenge to discover how to present it in the most useful form, " he says.

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