Big Pictures Reveal Field Issues

Big Pictures Reveal Field Issues

The latest farm technology unleashes yield opportunities throughout the season

Technology’s quick-step march across farmland—led by precision and automation—is fueled by results. The popularity of aerial imagery continues to increase as high-resolution color photos, normalized difference vegetation index (NDVI) photos, thermal and satellite imagery and unmanned aerial vehicle (UAV) images evolve.

One of the big questions surrounding yield maps is how to view data, says Brad Beutke, Crop-Tech Consulting. The resolution, the length and width of each pixel, for any type of imagery is vital. The higher the resolution, the easier it is to pick out details. 

“Typically that’s why we don’t like to use satellite imagery, which can lead you in the wrong direction,” he says. “It comes in 30 meter or 50 meter form, and the quality is just not that good. At 5 meter resolution, we can see zones and where the water lays. At 2 meter resolution, we can see wheel tracks and small pockets in the field.”

All the imagery Beutke uses is done at 1 meter or less. Because of the altitude at which an airplane flies, 1 meter resolution is achieved as easily as 30 meter, and both are cheaper than satellite imagery. The airplane images offer better resolution and lower cost, Beutke says.

He also relies on high-quality color photos. Clouds can alter an NDVI reading, so color photos taken at the same time are helpful. The same principal applies to thermal images. 

“We had a client come in with an NDVI image that had weird lines and what looked like crop circles,” Beutke describes. “When we pulled up the color photos, the problem was revealed: shadows from windmills. He doesn’t even have a windmill, but his neighbor does, and the shadow was showing up in the thermal imagery.”

Beutke has used seven types of drones to collect imagery. UAVs can only fly up to 400', which means a picture can only include a few acres. Special software is needed to stitch images together. For Beutke, the processing side—stitching photos together—is the downside of drone imagery. Until a drone can fly at an airplane’s altitude, he doesn’t see drone imagery replacing airplane imagery. 

“Certainly drones are a tool we can use, but just not for large amounts of imagery right now,” he says. “The way we’ll be using drones in the near future, until we can fly them higher, is for going out in the zones on airplane maps. Send the drones out to red, yellow or green spots on the map and have a look.”

No one should think they have to spend $30,000 on a UAV because often a $500 or $1,500 drone will do all a farmer needs, Beutke says.

Matt Rohlik, integrated solutions manager for Haug Implement, Willmar, Minn., works closely with UAV technology and has a tight grasp on the scope of opportunity for agriculture that will open when drone technology passes through final regulation. “We’re looking at a repeat of the 1993-1994 scenario that covered the birth of yield monitoring and mapping systems,” he says. “That’s where we’re at with UAVs, and we’ll be there for at least the next year.”

In precision farming, it took roughly 15 years for yield monitor systems to go from inception to wide acceptance, but Rohlik believes agriculture will cut that time frame in half with UAV technology. In five years, UAVs will feature longer flight times, larger payload and more cameras. 

Whether NDVI or another evolving technology, sensor use is set to expand. “The more we do with sensors and UAVs, the cheaper and more sophisticated they’ll become,” says Earl Vories, USDA–Agricultural Research Service (ARS) agricultural engineer, Missouri Agricultural Experiment Station, Fisher Delta Research Center. “We have a sensor now that picks up Normalized Difference Red Edge. It’s the same type of calculation as NDVI, but it uses a different light band.” 

Other sensors can make additional measurements, such as plant height, that don’t yet fit UAV applications. 

In soil sensing, the idea of sensor fusion is gaining ground. Sensor fusion combines readings from different types of sensors and reveals more detail about soil variations in the same field. The data gives farmers a better picture of the productive capability and water-holding capacity of fields, allowing for better management decisions, says Ken Sudduth, USDA–ARS agricultural engineer, Columbia, Mo. 

“I think we’re headed toward one device composed of multiple sensors,” he says. “The device would automatically take the data and put it all together to provide improved soil information a consultant or farmer could use for management decisions.”

The future direction of crop sensors might involve causal stress detection within fields. “Right now, available crop sensors pick up the symptoms of stress, but nothing else. If a sensor could reveal whether variation is nitrogen stress, nematode stress or water stress, it would swing open major new doors and make management so much easier,” Sudduth explains. “Is that a possibility? It might be because there is research under way toward sensor improvement. It’s too early to know about success, but researchers are looking in that direction.”

In addition to crop sensor technology, soil moisture sensors are rapidly evolving, as they become easier to maintain and less costly, says Tom Penning, president, Irrometer, Riverside, Calif.

Irrometer has developed a mesh radio networking product, Irromesh, that gives farmers wireless soil moisture data-logging capabilities. Sensors are connected to solar-powered radio nodes in the field, and data is sent to a base for collection. The data can be collected in the field or wirelessly transmitted and viewed through a web portal. 

“With Irromesh, farmers get information about moisture levels at various spots in their fields to help them decide when and how long to run irrigation systems to improve water use efficiency,” Penning explains.

There’s no programming for the user; the radio system does it all. When powered up, the nodes know where to send data. If the soil type is uniform, the sensors are placed every 10 to 20 acres, but frequent soil changes demand more sensors.

Sentek’s Drill & Drop probe, which is capable of measuring moisture, temperature and salinity, is also catching irrigation attention. 

“The slurry method used by many other probes can cause misleading soil issues,” says Justin Prather, Southern Ag Consulting, Starkville, Miss. “If you remove soil, add water and then place it back in the ground, you’re only coating the probe with soil that might be different at deeper or shallower depths.” 

Drill & Drop, developed in Australia and distributed in the U.S. by High Yield Ag Solutions, is designed for a snug fit and offers a true measurement at each point of the probe, regardless of depth. Acreage coverage from a single probe can depend on crop and soil type. Prather recommends one probe per irrigation well. 

“If a producer has a well that waters 160 acres with the same crop and soil type, one probe will cover that portion of land,” he says.

Advances in imagery, UAVs and sensors are on a converging path. Technology is the core of modern production, and farmers are keenly aware that few industries have as much skin in the precision game as agriculture. Stay tuned.  

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