Sidedress Pass Could Cause a Pinch

Soil compaction and pinch rows can reduce crop yields by negatively impacting water flow and compacting roots. The Farm Journal Test Plots program has conducted numerous studies through the years on compaction using both wheels and tracks. The findings include:

• Increased surface area, whether tire or tracks, decreases the depth of compaction. Tracks can provide more surface area than traditional tires.
• Wide tracks work great in pre- and postseason applications, especially when the ground is soft.  
• Traditional tracks can cause berming and increase crop destruction when turning on row ends.

Because wide tracks don’t work for in-season applications, some farmers are adding narrow tires or running duals or even triples. “Although depth of compaction is diminished using multiple sets of narrow tires, it causes compaction in the root zone on both sides of the row that grows in between the two tire tracks,” says Isaac Ferrie, who helps oversee the Farm Journal Test Plots program. “With bigger and heavier equipment, the ‘pinch row’ effect can worsen, especially when soil conditions are less than ideal.”

When studying pinch row compaction caused by central-fill planters, we observed, in years with increased moisture at side- dress, yields were negatively impacted where the sidedress application was made rather than where the planting tractor ran.

“This makes sense as farmers are more willing to sidedress than plant in wetter, more compactible conditions,” Ferrie says. “The potential damage at sidedress could be just as bad or worse than at planting.”

To further study the compaction and pinch row effect in the sidedress pass, in 2017 and again in 2018, the test plots team evaluated three setups: a tractor with single tires, the same tractor with duals, and a similar tractor with rear tracks at 120" spacing.

Our goal was to better understand the impact of the three footprints. Limiting the compaction to one side of the row versus both seems to have less of a negative impact on root development, which can prompt farmers to go back to single tires. Less surface area equals deeper compaction, but only on one side of the row.

The challenge is most applicators’ tire spacing is set up on a wider center than the inside duals of the tractor. To allow for in-season application the tire is also narrower for a smaller footprint.  

Tracks are an alternative to single tires to increase surface area and limit the depth of compaction. But if tracks don’t align with the applicator tracks, the chance for pinch row issues still exists, Ferrie warns.

Farmers often question using tracks in season because they worry about damaging crops when turning on the row ends. Using the New Holland tractor with SmartTrax there’s less concern of berming—and the track spacing can be set to 120" to match the tire spacing of pulled implements to further reduce the pinch effect.

That brings us to the second portion of the research: analyzing compaction and yield in areas where the sidedress application matches up with the tracks of the planter tractor and comparing those results to the areas where the sidedress tracks run in virgin ground.

“In the past, we have seen subsequent passes over the same tracks cause less damage with each additional pass versus making that same pass on virgin ground,” Ferrie says.

Based on penetrometer readings, the New Holland with SmartTrax limits compaction to one row. The level of compaction is similar to what the applicator caused. Running a tractor with single tires, which didn’t line up with the applicator tires, caused as much of a pinch row effect as duals.

Decreasing the significance of pinch rows ultimately resulted in modest yield increases the past two years, but it was specific to soil type. The benefit is expected to be greater if soil conditions are wet, which wasn’t the case in 2017 and 2018.

Addressing compaction and pinch rows isn’t going to result in a huge yield gain. “A 3-bu. to 5-bu. improvement is big,” Ferrie says. “And while that gain doesn’t justify buying a new tractor, it’s worth considering the pros and cons of tracks and tires if you’re already shopping.”

Thank You to Our Test Plot Partners

Our thanks go to: Blu-Jet, Case IH, New Holland, Just a Mere Farm, McLaughlin Dooley Farms and Crop-Tech Consulting. Their efforts make it possible to share our research with you.