Soils Exam 3

bulk density

mass of dry soil/total volume of soil

Porosity

1 - (bulk density/particle density)

percent water by weight of soil

mass of water/mass of dry soil

base saturation

sum of bases/CEC

3 subfields of soil science

physics, chemistry, and biology

soil physics master variables

bulk density, soil texture, soil structure

soil chemistry master variables

pH and redox status

soil biology master variables

pH and substrate quality

compaction

compression of an unsaturated soil body resulting in reduction of the fractional air volume

consolidation

compression of a saturated soil by “squeezing out” water

bulk density in excess of ____ limits plant growth

1.6 g/cm³

matric potential

Negative pressure due to attractive forces between water and soil solids

In unsaturated soil above water

Adhesive forces and capillarity

Aids in supplying water to plant roots and in engineering applications

gravitational potential

Force of gravity drawing the water toward the Earth’s center.

Important for helping to move water downward after a heavy precipitation or irrigation event.

Helps to recharge groundwater.