Someone once said the only farmer who doesn’t have soil compaction in his field is the one who never looks for it. That may be a bit harsh. However, most agronomists today believe that if you look hard enough, you will likely find compaction.

Steve Gauck, a regional agronomy manager for Beck’s, based in Greensburg, Ind., says just because you find soil compaction in your field doesn’t mean you are doing things wrong. Beck’s sponsors Soybean Watch ’24.

“Sometimes soil compaction can be the cost of doing business, especially in a wet year,” Gauck says. “The 2024 season was a prime example. Some were able to plant soybeans early. Others thought soils were still a bit tacky and waited. That was likely the right call in some cases, although yields for early-planted soybeans tended to come out on top.

“However, where it turned wetter in May, and stayed wet for a while, some wound up planting in late May even though conditions weren’t ideal. The calendar was working against them. Waiting until later to plant doesn’t guarantee that you will have better soil conditions for planting.”

Finding soil compaction

To find soil compaction, take a tile probe to the field and poke it into the ground at various locations. If it meets resistance, often a few inches below the surface, that is likely soil compaction, Gauck explains.

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Or you can borrow or invest in a soil penetrometer, which is a steel rod much like a tile probe, but with a gauge attached to it. The harder you must push to get the probe into the ground, the higher the soil compaction reading. Most register in green, yellow and red zones, with yellow and red indicating soil compaction building up.

“You can also diagnose it just by looking at plants,” Gauck says. “Notice the contrast in the two plants pictured [above]. The taller one was dug from an area without soil compaction. The shorter one was growing in compacted soil, and was about half the size with about half the pods.”

While weather during the growing season plays a big part in determining if you will see much effect from soil compaction, especially in soybeans, compacted layers likely still exist, even in wetter seasons when the impact on growth is less pronounced.

Decades ago, Gary Steinhardt, a Purdue Extension soil specialist, found that trying to quantify yield losses due to soil compaction was difficult. Yield outcome varies with the type of season. Plus, soil compaction is seldom uniform throughout the soil, but instead varies in intensity from place to place.

“You can also see the effects of soil compaction by digging roots,” Gauck explains. “I start checking early in the season, digging smaller plants to see if the planter formed sidewall soil compaction during planting. If so, young roots can have a hard time breaking through it. Roots that twist and turn not far below the surface often were impacted by this type of soil compaction.”