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On-Farm Trial Compares Hydraulic Downforce to Air Bags

Do your cornfields have that picket fence look? The Boenders’ fields didn’t. Better managing down pressure for even emergence and stand was at the top of their list as they headed into the 2015 growing season. 

“When I’m in the cab, downforce is the number one thing I have the least amount of control over,” says BJ Boender, who is in charge of the Oskaloosa, Iowa, family’s John Deere 1790 planter. “I could adjust the air bag system on-the-go, but I couldn’t adjust it as fast as I needed to. When I look at our maps, it’s clear I’m getting too much downforce in some areas and not enough in others.”

In search of technology that would provide even seed spacing and better emergence, Boender turned to Nathen Deppe, manager, Centrol Precision Ag, who suggested two options.

“I made the recommendation for Precision Planting’s vDrive or DeltaForce system,” says Deppe. “The investment for DeltaForce is about $1,500 to $1,700 per row; vDrive would cost around $1,000 to $1,200 per row.”

Because the Boenders’ planter is set up for 30-inch rows for corn and 15-inch rows for beans, it added to the cost due to the electronic structure. They chose DeltaForce for two reasons.

“First, the Boenders were looking to do more no-till/minimum-till, and this system allows them to achieve a better stand by controlling the amount of force needed to maintain the proper seeding depth without applying too much down pressure and compacting the seed trench, leading to yield loss,” explains Deppe.

“Second, they have an interplant planter,” he continues. “If they went with vDrive, they would have to add it to the bean rows. There hasn’t been enough research done to prove a return on adding vDrive to bean rows. Going with DeltaForce allowed them to put it on the corn rows and to get the best return on investment possible.”

Evaluating benefits

To evaluate the agronomic and economic benefits of DeltaForce, Successful Farming magazine asked Matt Darr, associate professor, Iowa State University, and Nathan Paul, operations manager for Iowa Soybean Association On-Farm Network, to calculate return on investment as well as performance results through field trials.

For 2015, half of the Boenders’ planter was converted to hydraulic downforce. The other half used air bags. Load pins were added across the entire planter so weight was measured on every single row.

Eleven strip trials were placed in the Boenders’ fields to test hydraulic downforce vs. air bags. Strips were a minimum of 300 feet long. When scouting, Darr and Paul spatially picked GPS points within each of the treatments. Typical counting protocol was set up for scouting plants and done across six paired treatments. There were 12 points across the field where population data was collected. 

“We analyzed strips rather than an entire field, and we consider those the most fair comparison for the way we do our quality control,” explains Paul. “Once we got the yield data back, we overlaid it on the imagery collected during the season to remove trouble spots.”


Inconsistencies in yield data, like wet spots, were filtered out to give a fair comparison.

Based on the data, there was no significant yield bump between hydraulic downforce and air bags. On average, the yield difference showed hydraulic downforce lost 1.2 bushels an acre.

“The advantage of downforce, in general, has a lot to do with Mother Nature,” says Darr.

Mahaska County, which is where the fields are located, saw a dry planting season beginning in early April followed by an extraordinarily wet summer, which meant little stress on crops. Some fields did, however, experience lodging, and the direction they were harvested may have had an impact on yield.

Although there was no marked difference between the two, Darr says it’s important to understand the value proposition around a concept such as hydraulic downforce.

“The value of downforce products come from improved seed-to-soil contact and the right amount of downforce to minimize compaction. This is a different return on investment than input-saving technologies like auto steer and section control,” explains Darr.

“I was surprised at how often DeltaForce not only used down pressure on the harder spots but also used the up pressure on the softer places in the field, which helped minimize compaction,” says Boender.

While you may not see the effects in year one, Darr says you will over time. “In wetter years or in farms with a lot of soil diversity or with a mix of residue conditions, the benefit of downforce will be greater,” he notes. “It helps you manage risk and reduce a complex part of the planting operation in the long run.”

Mitigating risk

The element of risk mitigation is an important one to consider. “Being able to have more control or automated control of the technology from the cab is going to have as much benefit in reducing loss in a tough year. Yet, it may not necessarily be a yield advantage in a good year,” says Darr. 

“Even though the first year doesn’t show more bushels, I am not discouraged because it made planting corn easier. Having DeltaForce on one side of the planter helped me better manage the other side,” says Boender. 

He’s also not second-guessing seed placement. “I’m not continually getting out of the tractor to check seed depth and then change settings,” he says. “With this technology, I’m confident I’m planting that kernel of corn where it needs to be. That’s my return on investment.”

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