APES Soil ONLY

not including the other parts of agriculture

what is arable land

soil that is good enough to grow food

what is the limiting factor for humans on the planet (in argiculture)

arable land

what differs different kind of soils

1. geography

2. parent material

3. climate

4. age

5. presence of soil organisms

what is in the mix that soils are composed of

1. weathered rocks

2. partially decomposed organic material

3. air

4. water

5. organisms

how long does soil take to form

can take about 1000 years

soil is not only formed with related bedrock but…

broken down parent material that is transported far by water & wind

what influencfes the texture and porosity of the soil

particle size of the broken-down parent material

give me the particle sizes from largest to smallest

1. sand

2. silt

3. clay

what type of soil is the best for agriculture

mix of sand, silt, & clay called loam

what pattern or structure is soil usually formed into

horizontal layers called soil horizons

what can looking at the cross section of a soil reveal

its profile:

-usually all living organisms close to surface

what is at the surface of the soil

O horizon

what is the O horizon

layer composed of partially decomposed organic material and/or leaf litter

what layer is below the O horizon

the A horizon

describe the A horizon

1. known as topsoil

composed of mineral-containing weathered parent material and organic matter called humus

what is “imperative” for land to be arable

a thick A horizon

describe plants and the A horizon

plants spread most of their roots to absorb water and minerals in the A horizon

-seeds also germinate in this layer

whats another name for the A horizon

the zone of eluviation

where is the B horizon located

beneath the A horizon

how does the amount of organic matter differ from B horizon to the others

has lower concentration of organic material than the first 2 zones

!!!!!@@@@@@@@???describe the accumulation of minerals

-higher concentration of mineral particles

-overall lot of accumulation of materials

what is the B horizon also called & why

it is also known as the zone of illuvation bc:

this zone is the lowermost zone of root penetration

where is the C horizon located

beneath B horizon

what is the C horizon composed of

weathered parent material sitting on top of bedrock (somtimes labeled D or R horizon)

what is used to determine textural classes of soil

the soil triangle

why do we use soil triangle

to determine textural classes of soil from the percentages of sand, silt, and clay in the soil

what is 1 property that determines if a plant is able to grow in a specific environment?

soil texture

how to scientifically determine soil texture experimentally?

the percentages of sand, silt, and clay have to be measured

in a soil triangle which component comes first (sand, silt, clay)

clay side first