- minerals, organic matter
(including living things), water, and air
- Carbon from air and rest
from soil (including water from soil)
- Soil Profile
- surface litter: fresh
and partly decomposed organic matter.
- topsoil: where most
living things and nutrients are.
- zone of leaching:
where dissolved materials from above move down.
- subsoil: accumulated
materials from above.
- parent material:
partially broken down rock, source of minerals and inorganic material
in soil.
- bedrock: underlying,
unweathered rock.
- Parent material, climate,
organisms, topography, time
- 200 - 1000 years
- When vegetation is removed,
the thin topsoil decomposes, leaches, and erodes quickly, leaving the hard,
red, iron-rich soil that is unproductive (and this only takes a few years).
- Desert pavement:
tightly packed, course sand and gravel that may form on the surface of desert
soils after wind and water remove the finer, lighter materials. Cryptogamic
Crust: forms on the surface of the soil and is composed of mosses,
lichens, algae, and cyanobacteria. It helps to build the soil and to reduce
erosion.
- Movement of topsoil from
one place to another.
- Wind and moving water
- Vegetation removal because
roots hold soil together and block wind and moving water.
- About 90% attributable
to overgrazing, deforestation, and cropland agricultural activities.
- Major Effects
- Loss of productivity
- Increased air and
water pollution
- Increased flooding
- Increased gullying
(loss of productive land)
- Increased costs due
to having to use more fertilizer, irrigation, etc.
- Terracing, contour farming,
strip cropping, windbreaks, gully reclamation
- Rising but now leveling
off or declining
- Wheat and rice most,
then corn, then potatoes.
- They are all annuals
and require frequent soil disturbance. Also less genetic variability among
our crops leads to less adaptability thus greater susceptibility to disease,
pests, climate change, etc.
- Industrial Revolution:
farm machinery, etc. Green Revolution: pesticides, irrigation, fertilizer,
higher-yielding crop varieties
- Depends on rate of population
growth and our ability to increase the amount of food available.
- Making more food available
- New land into productivity:
convert land to agricultural production of food
- Increase yields:
grow more food per acre
- Improve use of existing
food supply: eating lower on food chain, better nutrition, better storage,
better distribution
- Future potential for
each
- New Land: very little
potential; we're losing land as fast as converting land
- Increased Yields:
we're maxing out on pesticides, fertilizers, irrigation, but there is
potential in new crops
- Improve Use: there is potential here too
|