Soil Compaction - The Hidden Threat to Crop Yields

By Jamie Martin

Soil compaction, often called the "silent thief," is a growing concern in agriculture, especially with the trend towards larger farms and heavier equipment.

Compaction occurs when soil porosity is reduced, hindering root penetration and impacting crop yields. While its effects may not always be immediately visible, they can persist for years, particularly in the subsoil.

Research highlights the long-term consequences of compaction. Soil compacted with heavy axle loads showed a 15% yield reduction in the first year, with a lingering 3% reduction even after a decade.

This persistence is attributed to subsoil compaction, which is less affected by natural processes like tillage, freeze-thaw cycles, and biological activity that can alleviate surface compaction.

Tillage itself can contribute to compaction. Repeated tillage at the same depth can create a plow pan, a dense layer with low porosity and high resistance to root growth.

This is commonly associated with moldboard plows but can also occur with reduced tillage tools if used consistently at the same depth.

No-till farming, while generally beneficial for soil health, can also be susceptible to compaction. Without tillage to alleviate compaction, the effects of heavy equipment can be significant, especially in dry years.

A Penn State study showed corn yield reductions of 27% in a dry year and 14% in a wetter year following compaction in a no-till field.

This highlights the importance of tire pressure and footprint in managing compaction. Wider tires with lower pressure can significantly reduce yield losses.

Beyond yield impacts, compaction affects other aspects of the farm ecosystem. Earthworm populations and activity can be drastically reduced, hindering soil health and nutrient cycling.

Compaction also impairs water infiltration and drainage, leading to anaerobic conditions, nitrogen loss, and nutrient deficiencies.

Understanding the causes and consequences of soil compaction is crucial for farmers. By adopting practices like controlled traffic farming, reduced tillage, and proper tire management, farmers can mitigate compaction and promote healthy, productive soils.

Photo Credit: istock-chas53