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Strategies for Mitigating Soil Compaction

Dr. Scott Shearer, Professor and Chair of Food, Agricultural and Biological Engineering at The Ohio State University, provided tips on how to lessen soil compaction and offered insight in what the future holds for agricultural equipment that will cause less soil compaction during the October 4^th Chicago Farmers’ Zoom meeting.

One of the biggest culprits in soil compaction is the increasingly heavy equipment, said Dr. Shearer. He related the largest John Deere tractors tested at the University of Nebraska Tractor Test lab increased in ballasted tractor mass at a rate of 150 pounds per year from 1920 to 1960, and from 1960 to 2020, with the advent of the diesel engine, the rate of increase was 900 pounds per year. He said there has been a continual increase in tractor engine power and that ballasted tractor mass increases as well. Today, U.S. farmers manage an increasing number of acres given the corresponding increase in equipment size.

He said the march toward bigger continues. Dr. Shearer noted that a 2,500 bushel loaded grain cart weighs nearly 95 tons. The magnitude of large grain cart axle loads results in soil disturbance to 40 inches deep in the soil. Compaction will continue to limit agricultural productivity for the foreseeable future unless the current trend in equipment size can be reversed.

Dr. Shearer said that an ideal soil is composed of 50 soil particles and 25 percent void space for air and 25 percent void space for water to support crop growth. When soil becomes compacted, the void space is reduced and unfavorable growing conditions are created. These deleterious effects of soil compaction can last up to 10 years, although tillage can partially mitigate the situation, he said. He added that recent field tests at Ohio State have shown a 30 bushel per acre yield reduction attributed to grain cart trafficking of wet soils.

Dr. Shearer also discussed the trend toward higher ground speeds in planting and tillage operations. He said that Great Plans’ TuroMax provides a good example of this shift in tillage speed noting the tool works best at speeds of 6.0 to 9.0 miles per hour for residue sizing and light tillage. Many manufacturers are now offering high speed disks such as Horsch’s Joker RT with a recommended ground speed of 8.0 to 10.0 miles per hour. Ohio State has operated Case IH 2000 series planter at ground speeds approaching 18.0 miles per hour in replicated high speed seeding trials. At the end of the season, yield data collected from these strip trials revealed no significant difference in harvested yield. Given the trend toward higher ground speeds, “farmers might think about using a seat belt, considering what might happen under less than ideal conditions,” Dr. Shearer said. He added that it may be possible to mitigate soil compaction using deep tillage tools such as Case IH’s 875 Ecolo-Tiger.

Dr. Shearer said that prescription tillage is becoming more popular. Deep tillage is now an option in fields with rock outcroppings or shallow tile drainage systems given the ability to map and control tillage depth.

Another way to mitigate the potential for soil compaction is the selection and use of properly inflated Increased Flexion (IF) and Very-High Flexion (VF) tire technology. IF and VF technologies allow the tire sidewall to flex, thereby increasing the soil-tire contact area and  in turn, reducing soil-tire interface pressures. Central tire inflation systems allow the tractor operators to change tire pressures on-the-go when transitioning road to field and back for optimal performance under either condition.

Dr. Shearer said that automation will change agriculture. For example, AGCO’s Xaver is a single row planter-tractor combination; it is a smaller, autonomous piece of equipment.

He noted that Deere purchased Bear Flag Robotics and CNH Industrial will purchase Raven; both companies have a significant stake in automating tractor operation. “We are seeing a trend toward the use of smaller machines that can run 24 hours per day,” said Dr. Shearer. He pointed to SwanFarm, an Australian company that is leasing small autonomous sprayers to farmers. He shared that the cost of application on fallow ground, exclusive of chemical and fuel cost, is $1 per acre.

He said that autonomous, low-power vehicles, approximately 100 horsepower, will significantly reduce soil compaction. Dr. Shearer added that this factor may likely drive the adoption of autonomous machinery.  He added that machine intelligence, edge/fog computing and broadband internet will enable adoption of the autonomous equipment. Additionally, the smaller machines will allow logistics repair services at the field. “Farmers won’t tolerate a machine not running 24/7,” said Dr. Shearer.

Regarding artificial intelligence in agriculture, Dr. Shearer said there is a 70 percent reduction in herbicide usage using AI. Intelligence machines are increasing reliance on broadband in rural areas. Google, Facebook, and Amazon are driving the spread of broadband usage.

Regarding artificial intelligence in agriculture, Dr. Shearer indicated that John Deere is reporting a 70 percent reduction in herbicide usage using AI with one of their recently launched sprayer products. Dr. Shearer went on to indicate that intelligence machines of the future will rely heavily on broadband internet access in rural areas. Google, Facebook, and Amazon are driving the adoption of AI in many industries.

In response to a question, Dr. Shearer said that some farmers use increasingly larger grain carts as a substitute for trucking capacity. The potential for damaging soils increases as larger carts transverse more of the field until fully loaded. “Farmers would be better off with another truck rather than larger grain carts,” said Dr. Shearer.

Following a question about sustainability, Dr. Shearer said that the focus of university research has shifted to soil health and at the expense of soil compaction as equipment size continues to increase. He noted the difficulty in measuring soil compaction because there are few tools to accomplish these measurements in a cost-effective and expedited manner.

He went on to say that “high axle loads of modern agricultural field machinery have the potential to cause soil compaction. The consolidation of soil particles likely increases run-off from rainfall events, which in turn contribute to off-site movement of nutrients and soil.”