1. BIG IDEA: Abiotic & biotic factors influence the environment
SOIL
BIG IDEA: Abiotic & biotic factors influence the environment

2. SOIL organic and inorganic
formed by weathering, breakdown as a result of the physical actions

3. WEATHERING
freezing and thawing
dissolving
attached organisms (lichens)

4. MINERAL CONTENT dependent on: type of rock forming soil
type of organisms in soil
amount of precipitation

5. 4 LAYERS OF SOIL topsoil:organic and organisms; contains humus
subsoil:rock particles and organics
rock parts: weathered
rock parts:
unweathered

7. Soil Horizons
O horizons or layers: Layers dominated by organic material; consist of undecomposed or partially decomposed litter (such as leaves, needles,twigs, moss, and lichens)

8. A horizons(topsoil): Mineral horizons which have formed at the surface or below an O horizon; mixture of partially decomposed organic matter called humus and some inorganic mineral particles

9. B horizons (subsoil): zone of accumulation; mineral-rich; contain more inorganic than organic material– mostly broken down rock consisting of sand, silt, gravel, clay

10. C horizons (parent material): transition to rock
R horizons: hard bedrock

12. As the roots of the grasses die they form a layer of organic matter called
The humus helps hold water and provides nutrients and food for the grasses and other organisms to grow.
HUMUS

14. SOIL CLASSIFICATION
organics
minerals pH
size of particles

16. is the symbol for the degree of acidity or alkalinity (base) of a substancepH
plants require a certain pH to grow properly
acid rain can ‘burn’ plants and the animals drink it

18. 1908
1969

19. SOIL CONSERVATION strip cropping terracing contour farming windbreaks
dams
crop rotation
fertilizers

20. SOIL CONSERVATION
strip cropping: cover crops are planted between strip crops so no exposed soil is left open to erosion

21. SOIL CONSERVATION
terracing: flat areas dug in hillside to prevent surface water (carrying soils) from running down hill

22. SOIL CONSERVATION
contour farming: rows across slopes on uneven landscapes; mounds formed by plow prevent runoff

23. SOIL CONSERVATION
windbreaks: used to prevent wind erosion, usually made of trees

24. SOIL CONSERVATION
crop rotation: growing different crops in succeeding years; prevents soil depletion (reduction of nutrients)

25. SOIL CONSERVATION
fertilizers: replace essential nutrients removed by crops; include natural (e.g. manure) and chemical