1. SOIL ORIGIN and DEVELOPMENT
SOILS are a SLOWLY RENEWABLE resource
It takes 100’s to 1000’s of YEARS for SOILS to DEVELOP…
…but they do GROW, CHANGE, and DEVELOP over TIME

2. ROCKS, MINERALS and NUTRIENTS
ROCK (solid bedrock of earth’s crust) is broken down to PARENT MATERIAL (smaller rocks) and through the process of WEATHERING is further broken down to SOIL
ROCK – Solid bedrock which is a mixture of MINERALS of DIFFERENT KINDS and PROPORTIONS 
MINERALS – PURE INORGANIC ELEMENTS or COMPOUNDS of a DEFINITE CHEMICAL COMPOSITION usually CRYSTALLINE in form  
NUTRIENTS – Dissolved IONS in water called the SOIL SOLUTION

3. ROCKS - 3 MAJOR CLASSIFICATIONS
IGNEOUS ROCK – created by the COOLING and SOLIDIFICATION of MOLTEN ROCK
LAVA (extrusive) & MAGMA (intrusive)

4. ROCKS - 3 MAJOR CLASSIFICATIONS
SEDIMENTARY ROCK – deposits of MUD and SAND (through wind and water erosion) that are CEMENTED together by CHEMICALS or PRESSURE

5. ROCKS - 3 MAJOR CLASSIFICATIONS
METAMORPHIC ROCK - formed when either IGNEOUS or SEDIMENTARY ROCK is subjected to GREAT HEAT & PRESSURE

6. SOIL FORMATION SOIL is formed from the WEATHERING of ROCK
PHYSICAL WEATHERING
FRACTURING due to expansion and contraction
Frost Wedging - freezing and thawing of water
Heating and cooling

7. SOIL FORMATION PHYSICAL WEATHERING EROSION or wearing down of rock
Water
Wind

8. SOIL FORMATION WEATHERING of ROCK CHEMICAL WEATHERING
DISSOLUTION - Water DISSOLVES minerals into SOLUTION

9. SOIL FORMATION CHEMICAL WEATHERING
HYDROLYSIS – Water reacts with minerals in rock create NEW, SOFTER COMPOUNDS

10. SOIL FORMATION CHEMICAL WEATHERING
OXIDATION – O2 reacts with minerals in rock to form NEW COMPOUNDS

11. SOIL FORMATION WEATHERING of ROCK
PLANTS ….can also PHYSICALLY and CHEMICALLY WEATHER ROCK
ROOT WEDGING – Plant roots PHSICALLY force open cracks by ROOT GROWTH
LICHENS – exude acid which CHEMICALLY WEATHERS rock

12. FACTORS AFFECTING SOIL FORMATION
The TYPE of SOIL developed depends on the amount of TIME a PARENT MATERIAL of a specific TOPOGRAPHY is exposed to the effects of CLIMATE and VEGETATION (or LIFE).
PARENT MATERIAL
CLIMATE
LIFE
TOPOGRAPHY
TIME

13. FACTORS AFFECTING SOIL FORMATION
PARENT MATERIAL – are broken up rocks that have started that process of WEATHERING
RESIDUAL SOILS - are soils formed in PLACE
Less common
Form SLOWLY from weathering

14. FACTORS AFFECTING SOIL FORMATION
PARENT MATERIAL
TRANSPORTED SOILS – are soils that have been TRANSPORTED and DEPOSITED from the original site to another
More common
Form FASTER
GLACIAL ICE
WIND
WATER
GRAVITY
VOLCANIC ACTION

15. FACTORS AFFECTING SOIL FORMATION
PARENT MATERIAL
CUMULOSE SOILS – soils that accumulate in one spot
Usually formed under WATERLOGGED conditions
Containing > 20% organic matter

16. FACTORS AFFECTING SOIL FORMATION
CLIMATE
Temperature
Decreased Temp >>> decreases weathering >>> soil forms slower
Decreased Temp >>> decreases decomposition >>> increases OM overall
Rainfall
Increased rainfall >>>increases leaching of nutrients
Increased rainfall >>>increases plants >>> increases OM

17. FACTORS AFFECTING SOIL FORMATION
LIFE
PLANTS affect soils
GRASSLANDS vs. FORESTS
SOIL BIOLOGY – all sorts of ORGANISMS that aid in mixing, OM decomposition, holding and releasing of WATER and NUTRIENTS

18. FACTORS AFFECTING SOIL FORMATION
TOPOGRAPHY- lay of the land
SLOPE – steepness of site
ASPECT – which direction the slope faces

19. FACTORS AFFECTING SOIL FORMATION
TIME
The longer the TIME, the MORE DEVELOPED the SOIL PROFILE
0 year – when soil first exposed to atmosphere
YOUNGER SOILS show fewer layers in the profile
OLD SOILS show more layers

20. SOIL PROFILE
To STUDY SOILS we dig a pit called a PEDON (3’ x 3’ x 5’ deep)

21. SOIL PROFILE SOILS change over time in response to 4 processes…
ADDITIONS
LOSSES
TRANLOCATIONS
TRANSFORMATIONS

22. SOIL PROFILE
Because of these processes… LAYERS are formed in soils called HORIZONS