The sand, silt, and clayey particles of the soil are cemented together in the soil to form natural units of compound aggregates separated by pores. This pro...

Answer Details

Soil structure refers to the way individual soil particles (sand, silt, and clay) are arranged and bound together into larger units called aggregates or peds. These aggregates are separated by pore spaces that allow the movement of air and water through the soil.

The cementing agents that bind soil particles into aggregates include organic matter (humus), iron and aluminium oxides, calcium carbonate, and clay minerals. The resulting structure affects how well the soil drains, how easily roots penetrate it, and how much air and water it can hold.

Soil structure should not be confused with the other terms:

• Soil texture refers to the relative proportions of sand, silt, and clay particles in the soil. It describes the size distribution of individual particles, not how they are arranged.
• Soil consistency describes the resistance of a soil to deformation or rupture, and how it feels (sticky, plastic, loose, friable) at different moisture levels.
• Soil colloids are extremely fine particles (less than 0.001 mm) of clay and humus that carry electrical charges and play a role in nutrient retention, but the term does not describe the aggregation process.