Barrons AP Environmental Science

Permeability The    measure of  the capacity    of  the soil    to  allow

water   and oxygen  (needed by  roots   and soil

organisms)  to  pass    through it. Low permeability

can lead    to  soil    salinization.

pH

pH  is  the measure of  how acidic  or  basic   a   soil

is. Various plants  have    different   soil    pH

requirements.   Acidic  soils   can be  caused  by

pollutants, such    as  acid    rain    and mine    spoiling,

and are most    often   found   in  areas   of  high

rainfall.   Alkaline    (basic) soils   have    a   high

amount  of  potassium   (K+),   calcium (Ca2+),

magnesium   (Mg2+), and/or  sodium  (Na+)   ions.

Pore    size Describes  the space   between soil    particles.  Pore

size    determines  how much    water,  air,    and

nutrients   are available   for plant   roots.

Size    of  soil    particle Soil   particle    size    (gravel >   sand    >   silt    >   clay)

determines  the amount  of  moisture,   nutrients,

and oxygen  that    the soil    can hold    along   with    the

capacity    for water   to  infiltrate.

Water-holding

capacity

Water-holding   capacity    is  controlled  primarily   by

the soil    texture and the soil    organic matter

content.    Soil    texture is  a   reflection  of  the particle

size    distribution    of  a   soil.   After   a   soil    is  saturated

with    water,  all of  the excess  water   and some    of

the nutrients   and pesticides  that    are in  the soil

solution    are leached downward    in  the soil

profile.

Soil Food Web

The soil food web is the community of organisms living all or part of their lives
in the soil. It describes a complex living system in the soil and how it interacts
with the environments, plants, and animals.