Advertise in Print | Subscriptions
Published January 24, 2013, 02:45 PM

Site-specific

New fluorescence sensors may help plan nitrogen application.

By: Mikkel Pates, Agweek

JAMESTOWN, N.D. — Science is bringing increased precision to agricultural practices and a tech-savvy younger generation is moving past pretty-colored maps and into a future of more accurate decision aids.

About 250 people — a mix of crop consultants and farmers — attended the second annual Precision Agriculture Action Summit Jan. 21 and 22 in Jamestown, N.D.

Raj Khosla, a professor of precision agriculture at Colorado State University, was the keynote speaker among an impressive lineup of regional and industry experts. He is immediate past president and a founder of the International Society of Precision Agriculture. He represents agriculture on national boards that advise NASA and others on global positioning systems.

Agriculture is the No. 2 industry using GPS, behind construction, Khosla says, and policy-makers need to know the importance of their policies and technologies to ensure the U.S. continues as a food-production leader. The world needs to produce nearly twice as much food between now and 2050, when world population hits 9 billion, he says.

In Colorado, Khosla and his group are looking for stable, decision-making precision agriculture tools — data sets obtained from different kinds of sensors — that are stable from year to year. To recommend these tools to farmers, he wants to make sure they have been tested in the lab and in farm fields. “We develop techniques in a way that are affordable to farmers,” he says.

Among other things, Khosla is studying a suite of “active optical” sensors and developing algorithms for decision aids. An optical sensor can use visible or nonvisible light to tell when a plant is deficient in something. But the sensors currently don’t have the ability to tell the difference between certain issues, such as nitrogen deficiency and iron chlorosis, for example.

“There’s a lot of science that needs to be done, too, in terms of how we can translate that information,” Khosla says, of sensors being developed in Europe and elsewhere. “Still, we should not be too critical of the technology that’s available right now.

Jon Langan, a consultant with Larson Grain Co. in LaMoure, N.D., was among several people from his company at the show.

Langan estimates that 50 percent of farmers are interested in zone-based management as a concept and 25 percent are taking steps to try it. Larson Grain does a lot of grid-sampling at three acres or less to make recommendations for phosphorus and potassium.

“We’re variable-rate fertilizer spreading,” Langan says. “We’re starting to spread ag lime at a variable rate … We’re interested in using optical sensors for nitrogen management.”

More research

Dave Franzen, a North Dakota State University soil science professor, is working with the North Dakota Corn Growers on a study started in 2010. It uses precision agriculture techniques to measure nitrogen rates and soil types, for recommendations in certain regions: west of the Missouri River, eastern medium-textured and clay soils, and long-term no-till fields. Recommendations from that multi-year study will be available in 2014.

Precision agriculture tools are getting better, Franzen says.

“… In about 1995, we found out that patterns were stable within a field with nitrogen, and even our other nutrients, and so we could go to the ‘zone’ approach,” Franzen says. “We found that we could get about the same information from that that we could with 10,000 samples” in the grid system on a quarter-section.

Khosla says the “active optical” sensors will help define those zones.

“Let’s say you have 10 fields on your farm and different yield goals for every field,” Khosla says. In terms of management zones, a large field will have different management zones that should be managed differently. “It’s a no-brainer,” he says. “The challenge is to draw lines within your large field.”

Asked by a farmer what was the best time of year to take a data “snapshot” to make a zone map for the next year, Khosla was cautious. One size doesn’t fit all, he says. It depends on the location, whether it’s no-till, conventional-till, irrigated or nonirrigated, what’s been planted before, and what crop is coming up.

Tags: