Tillage, at one time a go-to solution for loosening compacted soils, also creates poor soil structure and hardpan soils.
This reality – that tillage is part of the problem – is tied to soil biology and the way that tillage disrupts the natural order, says Jim Hoorman, an assistant professor at Ohio State University. “There is a downward spiral with tillage. The more you till the soil, the more you destroy its structure.”
It boils down to tillage introducing excess oxygen into the soil, speeding the burning of carbon contained in organic matter. Soil microbial populations boom and consume the glues in the soil that promote good soil structure. The result? Denser soil prone to compaction.
Rebuilding soil’s tilth factory
While deep ripping or vertical tillage offer a short-term solution, the long-term answer to soil compaction is to rebuild soil structure, says Hoorman.
That requires reducing or eliminating tillage, he adds. Adding cover crops to the rotation is a second key component. “It is not until you add cover crops that you complete the biological cycle,” he adds.
Changing the tillage equation is important to slow the breakdown of soil-particle glues and reduce disruption of soil fungi that produce them.
Cover crops increase the amount of time live roots actively grow in the soil. That is key, since active roots provide sugars, polysaccharides, root exudates, mucilage and associated microbial wastes that bind soil particles together into macro-aggregates. These binding substances are gradually consumed by soil microbes, so extending their lifespans is beneficial.
Hoorman notes that in a typical corn-soybean rotation, roots are active in the soil only four to five months of the year. Adding a cover crop extends roots’ active season, and effectively increases the size of the glue-producing factory to rebuild soils that resist compaction. Planting a cover crop after crop harvest results in active fall (cover crop) root growth in the fall, then again in spring before planting, Hoorman explains.