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Soil Sampling Goes Robotic
By Matthew Wilde
Friday, October 16, 2020 3:50PM CDT

On a cold, snowy November day last year, Steve Wallpe watched one of Rogo Ag's SmartCore autonomous robots scoot around his fields taking and bagging soil samples.

Two things instantly came to mind, recalls the Fowler, Indiana, farmer. He's glad it wasn't him pulling cores while shivering, and a robot with plenty of power to bore into hard soil at a consistent depth was doing the job.

"When a person starts out at 8 a.m. pulling samples by hand, they are gung ho," Wallpe said. "By 5 p.m., they're tired and not paying as close attention to make sure the probe goes down as deep as it's supposed to that can give inaccurate test results.

"This takes the human element out of it," he continued. "Robots take the variability out of sampling and give me a better result at the end to put on the right amount of fertilizer."

Wallpe's local Helena dealer hired Rogo Ag, a soil-sampling business headquartered in Wolcott, Indiana, for the first time to take soil samples on his farm. Six cores 6 inches deep were collected per 2.5-acre grid over 250 acres. Grid samples were tested to determine soil fertility and pH levels. Lime, potassium, phosphorus and other nutrients were variable-rate applied this year on those corn and soybean acres based on test results and yield goals. "I was able to put on less fertilizer because it wasn't needed," he explained. "The corn looks great where (Rogo sampled)."

Wallpe plans to have Rogo's GPS-guided robots soil sample the same locations at the same depth over all his 2,000 acres in years to come to get a more accurate picture of fertilizer needs. He samples fields every three to five years, depending on cation exchange capacity, crop rotation and yield goals.

"If you underspread (fertilizer), you sacrifice yield," said Rogo co-founder and CEO Troy Fiechter. "If you overspread, you're dumping money out the back of the truck."


Soil sampling is part of a growing trend of farm tasks performed by robots and automated equipment. Sabanto offers custom planting and cultivating with driverless tractors. Raven Industries sells aftermarket retrofit kits to automate farm equipment. Drones spray fields, check plant health and find cattle in vast pastures.

Fiechter said soil sampling is a natural fit for robots and is a good business opportunity.

"It just makes sense," he said. "It's a grungy job that no one likes, and the highest cost of soil sampling is labor. But, doing it by hand doesn't provide statistically sound data."

Fiechter's family significantly reduced soil sampling on its 4,500-acre Indiana farm because it lacked consistency and accountability. Knowing the importance of soil tests to make better fertility decisions, he put his Purdue University engineering degree to use and built a robot to collect accurate, repeatable soil samples in 2015.

Fiechter, with the assistance of other engineers and family, built several improved robots since then. The latest version on a Bobcat skid steer chassis navigates fields using boundary algorithms and a variety of obstacle detection sensors. GPS ensures soil samples can be taken within inches of the same spot year after year. Soil is collected with a hydraulic, self-cleaning auger bit at the requested depth every time. Cores are automatically packaged per grid or zone to send to a lab for testing.

Fiechter said his family reduced lime, MAP (monoammonium phosphate) and potash expenses from about $85 to $60 per acre without sacrificing production because of more accurate soil sampling using robots.

Beck's Hybrids Practical Farm Research compared SmartCore versus hand soil sampling in 2019. Results showed SmartCore was 10% more accurate taking soil samples pertaining to location and depth, and twice as fast as humans. Hand samples showed less nutrient concentration since core depths, which were supposed to be 6 inches deep, were inconsistent. Based on $85 per acre for lime, potassium and phosphorus, Rogo's accuracy return on investment on a corn/soybean rotation was $13.50 to $17.40 per acre, studies show.

"It's amazing what you can learn (and save) when you get more consistent soil fertility data," Fiechter said.


It's a matter of time before robots replace people as the predominant soil samplers in the country, Fiechter believes. Rogo operators transport robots, scout fields for obstacles and load the mission into the computer -- the robot does the rest, covering about 140 acres per hour.

Rogo commercially soil sampled 100,000 acres in 2018. This fall, the company projects it will sample 350,000 acres, primarily in the Midwest. Fertilizer dealers are its primary customers, followed by farmers. Rogo has four autonomous and nine semiautonomous robots. It charges $2.50 to $4 per acre to take soil samples and $4 more for analysis.

Other companies, such as Falcon Technologies and SoilHawk, offer automated soil-sampling machines for sale or hire. Both have self-contained, trailer-mounted systems that are towed by a pickup or UTV (utility terrain vehicle).

SoilHawk operators, for example, use GPS to drive the soil sampler to predetermined locations. Upon arrival, the operator presses a button, and SoilHawk clears the surface of debris, takes a soil sample using a self-cleaning probe at a predetermined depth and empties the soil in a bag. A core can be pulled every 20 seconds. The machine has 30 bags on a conveyor belt. If sampling 2.5-acre grids, that means 75 acres can be covered before bags need to be replenished.

"It's fast and accurate," said Ken Hasty, SoilHawk co-founder and chief sales officer. "This doesn't get worn out at the end of the day and scrapes away debris, so you get pure soil.

The SoilHawk costs $29,000. The company plans to do custom sampling this fall in the Midwest.


Robert Miller, technical director of Collaborative Testing Services' Agricultural Laboratory Proficiency (ALP) Program, in Sterling, Virginia, said the accuracy and accountability that robots and automation bring to soil sampling is a good thing. ALP assesses the accuracy of soil-testing laboratory results.

However, the former Colorado State University soil scientist expects adoption will be slow primarily due to cost and low commodity prices, which have forced some farmers to cut back on expenses, including soil sampling.

"On rented land, owners don't want to pay for grid sampling, and neither do renters," Miller added. "Bottom line is these costs get cut."

Jason Ackerson, an assistant professor of soil science at Purdue University, expects robotic and automated soil sampling to be adopted faster in fields used for seed production and research than commercial grain production.

"There is value getting a consistent sample every time," Ackerson said. "I think long term you will see more automation in all sectors of ag."


-- Rogo Ag: www.rogoag.com

-- SoilHawk: www.soilhawk.com

-- Falcon Technologies: www.falconsoil.com

Matthew Wilde can be reached at matt.wilde@dtn.com

Follow him on Twitter @progressivwilde

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