Subtle changes among photo, infrared and NDVI images of the same field can reveal insights for smarter management.
Aerial imagery can reveal insights about your farm
If a picture is worth a thousand words, then satellite and aerial imagery might be worth their weight in gold. In fact, you should review Landsat images (free from USGS/NASA) before you purchase or rent new ground, says Dave Gebhardt, Winfield Solutions director of data and technology.
"Looking at multiple years of images lets you see how the land was cared for and its general condition," he says. Landsat also serves as a good base for developing management zones and analyzing the relative vigor of crops throughout the season.
But Landsat is not a total solution. The limiting factor is its relatively low pixel size, 30 x 30 meters, or about 5 to 6 pixels per acre.
Farmers can use imagery year-round on their operations to look for drainage and tile function, weed pressure, nitrogen deficiency and insurance verification.
"If you want to see row-by-row differences, you won’t be able to see it on a Landsat image," says John Shanahan, DuPont Pioneer agronomy research manager. "If you want to see those details, you’re going to need a much higher resolution."
Farmers who want this higher resolution can tap into commercially available options. For example, Pioneer offers remote sensing imagery from RapidEye to farmers though its Field360 services. RapidEye delivers a pixel size of 5 x 5 meters, or 161 pixels per acre. Other options can dial in pixels measuring 1 x 1 meter.
A world of discovery awaits at these higher resolutions. "You have the opportunity to fix problems before they cause a real yield loss," Shanahan says. "That’s the true ROI of purchasing higher resolution imagery."
For example, one of Shanahan’s customers missed a fertilizer pass at the edge of one of his fields. The miss became apparent when reviewing subsequent imagery, and the problem was easily corrected. He says farmers with irrigated ground use it to detect malfunctioning nozzles.
One of satellite imagery’s biggest weaknesses is a cloudy day. Aerial providers such as Illinois-based Aerial Imagery Solutions (AIS) can fly under the cloud cover to take on-the-go photos, infrared or NDVI images for their customers. Bill Stocks,
president of AIS, says each type of image helps with better diagnoses.
Data Detective. "To get a good understanding of what’s going on, you often times have to look at all three images and then go ground-truth it," he says.
Stocks enjoys playing detective when reviewing aerial imagery. He can spot check strips, hybrid differences, dragline turnaround spots, where the semi-truck drove into the field at harvest and tile functionality.
Stocks is working on a regression analysis to see if early July imagery could predict final yield based on NDVI values. He is encouraged by its potential as a marketing tool.
"I’m excited about the possibilities of aerial imagery," he says. "What might sound like a luxury could be indispensable if you can use it to decrease input costs, increase yields and better market your crop."
- December 2013