Soil compaction

Strictly speaking, Soil Compaction is a REDUCTION IN SOIL PORE SPACE. When pore space is reduced the bulk density (weight of a given volume of dry soil) increases. Soil Compaction is often recognized and even defined (although improperly) as an increase in the "hardness" of soil. An increase in soil strength is only one of a number of changes that occur in soil when pore space is reduced. Ordinary soil is usually about half solid material and half pore space. At optimal field wetness, about half the pore space is filled with water. So, the soil as it rests in your field, is about half solid material, one fourth water, and one fourth soil-air. Some soils have more organic matter than others. In "typical" Pacific Northwest Soils not more than one or two percent of the solid material is composed of stable organic matter