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Remote sensing becoming vital crop tool

By Staff | Nov 19, 2010

The light-colored boxes on boths sides of the end rows illustrate the lack of nitrogen applied. This is either from not waiting for fertilizer to go through the system before starting or turning off the applicator too early.

ALGONA – Now that the crops have been harvested, it’s time for farmers to evaluate how well they did and what they can do to improve next year’s corn and soybean crops.

For a growing number of farmers, that evaluation process includes a tool known as remote sensing. While the name sounds high-tech, remote sensing means taking aerial photographs of their fields and evaluating the photos with the expertise of a crop specialist.

Farmers or other experts look for color, texture, pattern and association in the photo to identify problems.

“It’s a management tool that I think pays off. For what it costs me to do, it pays me back double if not triple,” said Jim Legvold, a Vincent farmer. “If you start stacking remote sensing with yield maps, that crop is telling you a story.”

Legvold said he’s been using remote sensing for about five years, starting as a participant in the Iowa Soybean Association’s On-Farm Network research program. He eventually expanded the practice to all of his fields after seeing the results.

This is an image of a field where there were skips in the anhydrous ammonia application. These are shown in the lighter vertical streaks in the photo.

Michael McNeill, a crop consultant in Algona, uses remote sensing with about 70 to 75 clients each year and has used it in some form since the late 1970s.

“We started out with simple things, like looking for tile lines,” McNeill said. Today, the process is more complex. For each of his clients, he said he hires a company that takes photos with a specialized camera from the belly of a plane at about 3,000 feet. At that distance, a single photo can show a 160-acre field. The cost is typically about $1.50 to $2 per acre.

Each photo is also geo-referenced, which means a farmer can use a computer to overlay the photo with a yield map from a combine and use a hand-held global positioning system to walk his field right to the problem area. Some issues are easily identified, but many are more complex and need more expertise.

Some common issues identified with remote sensing include nitrogen deficiencies, herbicide damages, insect infestations, soil compaction and identifying cost-effective areas to install drainage tile.

Remote sensing is also frequently used to settle lawsuits involving crop damage, McNeill said.

This is an image of a field where an herbicide overlap occurred in the first several passes. These are shown in the lighter horizontal streaks at the bottom of the photo.

“A lot of people can’t read the photos once they have them,” McNeill said. He compares it to a doctor who can point to an X-ray and tell a patient precisely where a bone is broken. “I can look at these photos and say that’s this or that because I’ve learned how to do that.

“There’s a tremendous amount of knowledge that can be gained. I can look at a photo of a cornfield and tell what kind of herbicide was used on the soybean crop the previous year. Each chemical has its own signature,” McNeill said.

Dean Coleman, a Humboldt farmer, uses a relative’s plane to take photos each August.

“We take pictures of anything that’s not ordinary,” Coleman said. “We look at the yield maps and compare it to what we saw from the air and on the ground and try to draw conclusions. Was it weather? Was it disease? Was it something mechanical?

“You can tell the next year if a practice is paying off with remote sensing. It’s another tool to use along with yield maps and scouting.”

Coleman has used remote sensing since 2006 after learning of it through ISA staff members. Coleman admits that it seemed strange initially to collect information from an airplane, rather than scouting the field on the ground. But now he’s a believer.

Last year, he said he saw a 20- to 50-bushel improvement in a field by adding more nitrogen after remote sensing showed an area that was nitrogen deficient.

“When you’re standing down in the field, there’s not that much size difference in the plants. It’s such a gradual change on the ground. When you get up in an airplane a couple of hundred feet, it really stands out to you,” he said.

McNeill said some of his farmer clients are initially skeptical, but he is able to convince them. In the winter of 2010, McNeil met with about 30 farmers who shared their remote-sensing photos and discussed strategies for the various problems that were identified.

However, one farmer in particular was skeptical about what the photo showed him.

“Did you use Starter fertilizer?” McNeill asked. The answer was affirmative.

McNeill then informed the farmer that the fertilizer nozzle on his No. 3 row planter was plugged. The farmer remained skeptical, so McNeill went to his farm after the meeting and showed him the problem on the planter.

“Now, he wants me to get a photo of his farm every year. Once they kind of understand and work with us, they get hooked,” he said.

Contact Dave DeValois at dwdevalois@yahoo.com.

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