Why are we concerned about soil structure? Soil structure stabilizes our soil to resist erosion by wind and water while aiding in nutrient holding capacity and cycling. Over the past century, we have observed high rates of soil erosion in the Palouse resulting in soil degradation. The key to this is the loss of soil structure due to aggressive tillage and the reduction of organic matter (OM). One of the most important components of soil structure is OM which influences stability, aids in water storing capacity, nutrient cycling, and helps to buffer soil acidity. These are all fundamental to maintaining soil quality and health.
Soil structure is the arrangement of the soil solid particles (sand, silt, and clay) allowing for open pore space between the particles. The ideal soil components include: air 25%, water 25%, minerals 45%, and OM 5%. Structure is determined by how the individual units are arranged, bound together, or clumped to form aggregates resulting in the arrangement of soil pore spaces between them. The clumping is the result of OM (carbon) and biology activity such as earthworms and fungi.“ Carbon is the food for the soil that builds the aggregates and makes the glue. Green plants take in carbon dioxide from the air and secrete carbon exudates into the soil.” Jay Fuhrer, Natural Resources Conservation Service, Menoken, ND. “When it comes to the glue, the fungi do most of the work. The fungi are comprised of long filaments that branch through the soil. Tillage breaks the filaments making it hard for the fungi to survive.”