There’s a solid reason why planters are increasingly pulled by four-wheel-drive tractors. And it’s not just a “power thing” for big planters. But even tractors with dual wheels can cause compaction on soft and/or wet soil.

“In years like this where you’re pushing soil moisture to get the corn crop in, there have been tremendous yield reductions caused by planter tractors,” explains Tom Kilcer, owner of Advanced Ag Systems consulting service at Kinderhook, N.Y. It even happens when duals are set close together, but aren’t centered in the row. Corn in those tracks or bordering them can suffer stunting you can see all year.

A better idea
Align your planter tractor’s 4wd or front-assist wheels to center between the rows — even if you have to space the outside duals to straddle rows. This minimizes churning compaction and keeps the tire weight away from the row itself, plus minimizing the affected rows.

Another option is using low-pressure radial tires. They can have less compaction than even a track-type tractor, says Kilcer.

Corn planter compaction?
Yes, even corn planters can cause plant-stunting compaction. That’s why Kilcer advises: “On marginal conditions where you aren’t waiting for the soil to dry, only fill the fertilizer tanks or boxes halfway to reduce gauge wheel down pressure. Yes, you may have to refill more frequently. But in wetter or more moisture soil conditions, it may have significant positive impact on final yield.”

Watch the down pressure on those closing wheels, he cautions, especially if you planted last year in bone-dry conditions. This year, if you have too much down pressure on rubber-edged or cast-iron wheels, they can cause incredible yield-limiting compaction right where the seed is located. Spiked wheels also can run too deep in wet conditions, and actually flick out seed you just planted.

One more thing: Get out your jackknife and check those seed slots. If the sides of the slots are smeared like a trowel in concrete, it’s too wet to plant.

You’ll have higher yields if you wait a day for soil conditions to improve. Well-growing late corn will yield more than early-planted stunted corn. Remember, any compaction you cause this year can limit yields for years hereafter.