Week 11 Study Guide terms

20 question terms

Soil water

Water found in soil above the groundwater (where plants live).

Adhesion

Water sticking to soil particles.

Cohesion

Water sticking to other water molecules.

Capillary Action

Water moving through soil pores without gravity because of adhesion + cohesion.

Infiltration

Water entering the soil from the surface.

Percolation

Water moving down through the soil layers.

Soil Porosity

The amount of empty space (pores) in soil that can hold water.

Macropores

Large pores that drain water quickly.

Micropores

Small pores that hold water tightly.

Hydraulic Conductivity

How easily water moves through soil.

Water Potential

A measure of how likely water is to move. Water moves from high to low.

Matric Potential

Water stuck to soil particles is always negative and stronger in dry soil.

Osmotic Potential

Effect of dissolved salts = more solute = lower (more negative).

Pressure Potential

Pressure on water. Positive pressure helps water move.

Gravitational Potential

Effect of gravity on water movement (pulls water downward).

Field capacity

The most water soil can hold after extra water drains away.

Permanent Wilting Point

When soil is too dry and plants cannot get water anymore.

Plant Available Water

Water that plants can actually use (between field capacity and wilting point).

Gravitational Water

Water that drains quickly after rain (not held in soil long).

Hygroscopic Water

Water held very tightly in soil but plants cannot use it.