An eye in the sky
Images produced by satellites and airplanes can detect problems with crop health not visible from the ground

By Deborah Hyk

Posted July 20, 2004: The latest agricultural technologies given coverage by mainstream media include new herbicides, pesticides, and genetically-engineered crops. Few if any of these items are permitted on an organic farm. But while they may not receive as much press attention, there are many technological advances that can improve the health and productivity of organic farms. One of these is satellite imagery.

At the latest count, twenty-three satellites circle the globe. Countless aircraft make shorter trips each day. Both of these, along their routes, may photograph the land below. The technology has advanced greatly, especially in the last few years, so these photos are far better than might be expected from pictures taken at such great distances. Farmers can easily recognize many features of their land. The photos can show the history and present condition of landscapes and cities, and can reveal threats to crops long before even the most observant farmer could spot them.

For Lee and Noreen Thomas of Moorhead, Minnesota, images like these have provided an opportunity to improve the productivity and stewardship of their 1,200-acre farm. The Thomases' crop rotation includes soybeans, blue corn, popcorn, wheat and barley. They also plant a variety of heirloom tomatoes, lettuces, peas, squash and many other garden vegetables for 'green baskets' to deliver to their neighbors.

The Thomases have worked diligently to care for their land and sustain their farm business. Noreen wrote and received a grant to learn about exporting; and the Thomases now direct market to Japanese buyers through a company called Northland Organic, along with a number of other companies like SK Foods. Often, just talking to other organic farmers helps the couple find new buyers for their crops.

As important as these markets are to the farm, stewardship is just as critical. Because the Thomases' farm is nestled alongside the Buffalo River, erosion is a concern and they watch the banks carefully. Some of their neighbors use pesticides and build dikes along the river. All these factors make the satellite images useful. The telltale photos show when something is going wrong, whether it is pests, spray drift or flooding.

Noreen has also used this technology to educate her neighbors—both farmers and non-farmers—about the fragile and changing nature of the planet we all live on. She has worked tirelessly to understand what’s revealed in the images and to put that knowledge to use.

Putting technology to work

Noreen’s first exposure to aerial imaging technology was at a conference, browsing the booth of the Upper Midwest Aerospace Consortium (UMAC). UMAC is funded by NASA and eight universities in Idaho, Wyoming, Montana and the Dakotas, and is centrally managed from the University of North Dakota (UND). At the booth, scientists displayed satellite-generated photos and explained the on-farm applications of the shots.

“My initial thought about this was that it was kind of pie-in-the-sky,” says Noreen. She wondered what kind of bill she’d get if she dared to use it. Yet she was curious enough to ask, and found out that the images are available free of charge. The difficulty is in understanding what they show.

Noreen's curiosity led to an arrangement between the Thomases and UMAC. Lee and Noreen would take a class, which cost $25, to learn to read and interpret the satellite images. Then they would share what they learned with others in their community, and give ongoing feedback to UMAC regarding the benefits and practical applications of the technology.

The Thomases were the first organic producers in the area to use UMAC’s imagery. They are also part of what Santhosh Seelan, research associate professor at the University of North Dakota and lead scientist for UMAC’s Crop and Range Alert System, refers to as a learning community, comprised of farmers and others who’ve taken the UMAC class and are actively using the imaging technology. These individuals continue to meet regularly to share experiences and insights.

“The first year we offered classes, we had 20 farmers sign up,” Seelan notes. “Last year, we had 200 farmers.” To this day nearly 300 farmers have been through the course; the numbers increase each year through word of mouth about the benefits of the program—and through the efforts of people like the Thomases.

In addition keeping in touch with the learning community, Noreen studies and interprets the images with other farmers in her area, both conventional and organic. She’s happy to help her neighbors learn how to better manage their farms. Plus, she has the right approach—she tells people how they can use the information.

From the beginning, Noreen says, she knew what she’d hear from farmers: “What am I going to get from this to make my time and effort pay off?” The answer: the ability to precisely identify and deal with problems in farm fields.

Reading satellite and aerial images

Above: A ground picture showing a desiccated potato field to the far left and a sugar beet field center and right. The yellow strips extending into the sugar beets are drift damage from aerial application of desiccant to the potatoes. Right: An aerial picture using green, red and infra-red bands. Damaged areas show up darker and are highlighted with yellow lines; arrows indicate maximum damage due to overspray along the flight path. Using aerial images, the total damaged area was estimated at 18.7 acres. (Photos courtesy of UMAC.)

Satellite images and aerial photos offer complementary types of information. Photos are limited in range but can be high resolution, offering a clear, readily-recognizable illustration of land features. Satellite images, by contrast, look very strange at first: their colors are called false colors, because they do not match what our eyes see. Satellite sensors detect electromagnetic radiation (EMR), which includes both visible light and non-visible wavelengths such as infrared; when a picture is created from satellite data, colors are assigned to different segments of the EMR spectrum. Yellow, for instance, can indicate heat radiation, often a sign of infestation. Wetness and flooding usually appear black. Varying shades of red show vigor or lack of vigor. Spray drift may appear as a brownish burgundy. The Thomases tap all of this information, and use it in concert with global positioning data in the tractor. In this way, they can add composted manure exactly and only where it’s needed, or spot-apply an organic herbicide such as citric acid (lemon juice) to eliminate thistle.

Improving drainage: Aerial images often reveal ongoing problems with standing water, shown in black. These can be assessed, and ditching can be modified to allow for better drainage. Because the images have been available for 30 years, the history of any piece of property can be examined before it’s rented or purchased.

Near the Thomases, a group of farmers wanted a large dike installed. Noreen was able to produce satellite images showing that this dike would make the Thomas farm even wetter. Locating this historical evidence helped prevent the construction of the dike.

Pests, disease and nutrient deficiency: “The satellites can also see things that we can’t,” Noreen notes. For example, the greens visible to the eye—the level of chlorophyll present in leaves—may not reveal problems that satellite imagery can detect. When lack of vigor is present, it is obvious when looking at an image. Any problems with insects or disease will also be apparent. Farmers can zoom in on affected areas in the images and then head to the fields to verify what exactly is going on. Targeting problem areas and implementing compensatory measures in those areas alone can help farmers reduce inputs and save money.

Weather damage: The photos can also add weight to crop insurance claims. Wind and hail damage, for example, can be clearly seen on the satellite images. “A copy of a downloaded image can be used to convince an insurance adjuster to give some kind of reimbursement,” notes Seelan.

The Thomases themselves have benefited from this. One year, their alfalfa crop was drowned after the fields flooded from persistent, heavy rains. Including a satellite image with their insurance claim simplified the process.

“Insurance companies like information about a problem as soon as possible,” says Seelan. He recommends that farmers send in images showing evidence of damage as soon as they have them, with a note telling the insurer that there will likely be crop loss.

Buffer strips: Unfortunately, the crop insurance typically carried by organic farmers doesn’t cover pesticide or herbicide contamination. Even so, satellite images can help an organic farmer prove that buffer strips are in place or determine if they require enhancement. Furthermore, notes Thomas, “Having an eye in the sky keeps people more honest." She adds that if a farmer has nothing to hide, then there will be no reason to worry about being photographed from above.

Drift: In the Red River Valley in 2001, there was a case of spray damage on a conventional farm. A crop-duster applied a desiccant to a potato field (this is commonly done to accelerate die-back of the potato tops prior to harvest), and accidentally sprayed parts of an adjoining sugar beet field as well. The pilot who did the spraying and the sugar beet farmer whose fields were affected agreed that damage had occurred, but they needed a way to quantify the impact. “You could easily determine from the aerial picture which part of the crop was damaged,” Seelan notes. In combination with sugar beet samples, the aerial image facilitated a quick settlement between the two parties.

Keeping in mind what really matters

Working with satellite and aerial image technology has allowed the Thomases to take their concern for the environment one step further, beyond organic production. Four years ago, the Thomases realized they had to make some changes in their operation if they wanted to stay competitive with larger farms. At the same time, they became aware of the impacts of conventional farming on farm families' health. Farm families, they learned, have a rate of birth defects three times higher than the rest of the population. “We had to ask ourselves: What are we doing to our children?” says Noreen.

To learn more…
For more information about agricultural applications of satellite and aerial imaging technologies, visit the Upper Midwest Aerospace Consortium website at www.umac.org. UMAC collects both public (usually free) and private (usually fee-based) image databases for access from its website. (Free Viewfinder software is also available if needed.) For those in the UMAC region, regular classes are offered to help users interpret the graphic information.

Today, the Thomases invite Boy Scouts to their farm to learn about soil erosion and help plant red willows along the Buffalo River; they're also working with a geography teacher in Moorhead, Mike Benson, to bring information about satellite and Global Position Systems technology to the local schools. As a farmer, planting seeds is second nature to Noreen; she says she enjoys sharing her knowledge and message of stewardship with young people.

Lee and Noreen's family is the fifth generation of Thomases to farm along the banks of the Buffalo River. They hope their children will continue to farm the land, and preserve it for the generations to come. In all of their decisions, Noreen and Lee think about the children—because they know that ultimately, the farm and the planet will belong to them.

Deborah Hyk is a freelance writer based in central Minnesota.