Aquatic and Terrestrial Environments

Soil texture

the relative proportions of different sized grains of sand, silt, and clay in soil

Soil organic matter

plant, animal, and microbial residues in various states in decomposition

Soil Horizon O

Horizon containing a high percentage of soil organic matter

Soil A Horizon

horizon darkened by the accumulation of organic matter

Soil E horizon

horizon formed through the removal (eluviation) of clays, organic matter, iron, or aluminum

Soil B Horizon

broad class used for subsurface horizons that have been transformed substantially by a soil formation process (color and structure)

Soil C Horizon

A horizon minimally affected or unaffected by the soil formation process

Soil R Horizon

bedrock

Salinization

A build up of salts in soils to the point that they destroy the soil's physical and chemical properties and plants are not able to take up water due to the high salt concentration; often associated with improper irrigation

plant available water

the portion of water in the soil that plants can actually absorb and use for growth

percolation

the downward movement of water through soil and porous rock layers under the influence of gravity

field capacity

the amount of water a soil holds after excess water has drained away

permanent wilting point

the soil moisture level at which plants can no longer extract water, even though some water is still present in the soil

salinity

a measure of the dissolved matter within seawater

density

the weight of a substance for a specific volume

temperature

a physical property representing the average kinetic energy of a parcel of water

absolute salinity

the modern measure of salinity in a parcel of water

subsurface lateral flow

the movement of water horizontally through the soil profile typically in high porosity soil

macropores

larger pores into the lower soil profiles (gopher holes, plant roots, earthworm holes)

micropores

smaller pores into the lower soil profiles (natural pores)

vertical percolation

the movement of water in a downward direction through a porous medium. Primarily driven by gravity and capillary forces

runoff

the draining away of water from the surface of an area of land

evapotranspiration

the process where water moves from the land’s surface to the atmosphere

Aquic

poorly drained soils that are saturated when the soil temperature (at 50 cm) is above biological zero (>5°C). These soils typically display evidence of prolonged saturation in the form of redoximorphic features in the root zone

Udic

soils typical of humid or tropical environments that receive an even distribution of precipitation throughout the year. Soils are never dry for as long as 90 cumulative days or 60 consecutive days following summer solstice

Ustic

soil moisture conditions intermediate between aridic and udic and typical of semiarid, tropical and monsoon climates, where soil is moist during part or all of the growing season followed by a prolonged dry season at some point in the year

Xeric

a soil moisture regime with wet winters and dry summers typical of Mediterranean type climates

Aridic

a soil moisture regime that is dry (low plant available water) for most times of the year

mollisols

grassland soils that have large stocks of below ground soil organic matter

water potential

The amount of work that must be done per unit quantity of pure water to transport water over a defined distance

capillary forces

Water held by small pores due to cohesive attraction between water molecules and adhesive forces between water molecules and solids

Munsell chroma

A system used to describe soil color according to hue (spectral color), value (degree of lightness or darkness) and chroma. Chroma refers the intensity of color