Brian Dougherty says growers combatting compaction in their fields should realize they have bigger problems than merely compressed soil, and compaction is a symptom of poor soil function.

“Compaction is not natural or inevitable in modern cropping systems and, to be blunt, it usually can be traced back to three factors: too much equipment, not enough biology and excessive nutrient application,” he says. “To deal with compaction in the long run, we need to address what is not allowing the soil to function properly.”

Dougherty is a field consultant for Understanding Ag, a firm dedicated to helping growers implement soil health improvement practices. He preaches the importance of well-aggregated soils which contain roughly equal volumes of minerals, water and empty pore space. Since minerals (soil particles) and water are non-compressible, when heavy equipment travels over a field, the only thing to yield in the soil is the pore space — which produces compaction.

“For proper plant growth, roots need a gaseous exchange and pore space is where that occurs,” Dougherty says. “If the soil is compressed and pore space is compromised, there’s little room for water and oxygen/carbon dioxide exchange. When those components are shorted, soil microbiology suffers and in the long run so does crop performance.”

The interconnected pore spaces so important for water infiltration and nutrient exchange with crop roots are protected by soil aggregates held together by a natural glue — glomalin — produced symbiotically by mycorrhizal fungi from carbon-rich exudates shed by adjacent living roots.

“Those…