Soil Water

Explain the polarity and hydrogen bonding properties of water.

H2O is polar; oxygen atom bonded covalently

What is water potential?

how likely water is to move through a soil

What is soil moisture?

how tightly a soil holds water

Gravimetric moisture content calculation:

0g = wt of water/ dry wt

Volumetric moisture content calculation:

0v = 0g x Db

How does soil water move in a stratified soil?

micropore fill before macropores

Characteristics of saturated flow:

• positive potential

• all pore full and water moving quickly

• aka gravitational flow

Characteristics of unsaturated flow:

• negative potential

• water movement through micropores

• movement from thick moisture films (high matric potential) to thin moisture films (lower matric potential)

• aka capillary flow

What is capillary rise?

water pulled by matric potential up the sides of a tube in the soil (capillary)

smaller capillary=higher water level

What is a surface drain?

ditches across a slope if there is one

What are advantages and disadvantages of a surface drain?

• easy clean up and large carrying capacity

• expensive maintenance and interference with production systems

What is a subsurface drain?

drains that remove water from a zone of maximum saturation by moving water into a channel and empties it to an outlet ditch

How do septic systems work?

break down wastes that settle into a baffle so that it doesn’t clog

What soil properties are important for a septic system?

water must be able to percolate through the soil quickly but not so quick so that the water has time to filter