Section 2

Soil: a Vital Resource

• Dynamic substrate on the Earth's surface
• Long time to form
• non-renewable resource in human terms

Pedology

Function of Soils

• Anchor plants to earths surface
• source of plant and water
• habitat for numerous organisms
• support growth of autotrophs

 Mineral:  45%

  Water:   25%

Air:    25%

Organic:  1%-5%

Soil Horizons

Organic Horizon (O)

Upper layer contains loose, somewhat fragmented plant litter. Litter in lower layer is highly fragmented.

Soil Horizons

(A Horizon)

Mineral soild mixed with some organic matter. 

• Clay, iron, aluminum, silicates, and soluble organic matter are gradually leached from A Horizon. 

Soil Horizons

Depositional Horizon (B)

Soils Horizons

( C Horizon)

• Weatherd parent material

• may include rock fragments

• often lies on bedrock

• Color
• Texture
• Aeration
• Organic matter content
• Depth
• Inorganic composition

FUNCTION OF SOIL TEXTURE

SAND

(coarse texture soil)

• Rapid infiltration rate

• low water holding capacity

• low nutrient content

FUNCTION OF SOIL TEXTURE

CLAY(fine textured soil)

• Slow infiltration rate

• High water holding capacity

• High nutrient content

FIVE SOIL FORMING FACOTRS 

Parent Material

FIVE SOIL FORMING FACOTRS

Topography

Contributes to soil removal and deposition

FIVE SOIL FORMING FACOTRS

Climate

Influences the rate of soil  formation

FIVE SOIL FORMING FACOTRS

Organisms

FIVE SOIL FORMING FACOTRS

Time

period over which soil development occurs

• Topsoil: 1"/ 30 years
• Subsoil: 1"/ 300 years

• Deep fertile soils in the Midwest
• Australia does NOT have one 

Very valuable agricultural soil

John Steinbeck

chronicled the impact of the Dust Bowl

Soil Orders in the U.S.

Mollisols

• well-developed soils high in organic matter and calcium; very productive
• grass lands

Soil Orders in the U.S.

Oxisols / Andisols

Deeply weatherd, lateritic soils of moist tropics 

NOT represented in the continental U.S.

Soil Orders in the U.S.

Spodosols

• Acid, podsolized soils of moist, often cool climates with shallow leached horizon and a deeper layer of deposition
• Pine Forset
• "chalky look"

Soil Orders in the U.S.

Vertisols

• High content of swelling-type clays developing deep cracks in dry seasons
• "clay look"

Soil Erosion

Soil Eroison

Erosional processes

Soil Eroison

Natural (Geologic) erosion

Soil Erosion

Accelerated Erosion

increased rates of erosion cause by human activity

• over grazing
• deforestation
• farming/ crops-improper cultivation

• Agriculture that maintains integrity of soils and water so that it can contine to produce abundant, high quality food will into the future.

• reduce reliance on fertilizers,pesticides, and irrigation
• reduce soil erosion with ise agriculture practices

Climate

MEANS

• Temputure

• Precipitation

• Seasonality

CLIMATE

Extremes

• Drought

• Floods

• Heat waves

• Storms

• Large scale atmospheric and oceanic circulation system that influences weather and ecological processes on a global scale (75%)
• Difference in barometric pressure between Tahiti and Darwin, Australia
• High pressure over Tahiti and Low pressure over Darwin
• contributes ot a westerly flow of equatorial wind and ocean currents

• represents a reversal in the location of the high and low pressure systems to stop or reverse the direction of equatorial wind and ocean currents
• warmer ocean temp. in eatern Pacific, but cooler temps in Western Pacific.

Oscillation

Jetstream

• A narrow, high velocity air current flowing for west to east
• polar jet

P/E Ration

• Ratio of Precipitation to evapotranspiration
• index of water availability that is correlated with biome distribution

P/E Ratios for Biomes

Wet Forest

P/E Ratios for Biomes

Dry Forest

P/E Ratios for Biomes

Grassland

P/E Ratios for Biomes

Desert

• developed to explore the relationship between climate and vegetation
• Temp: Y-axis
• Month: X-axis
• Precipation: z-axis

Intergovernmental Panel on Climate Change 

(IPCC)

• international scientific body representing 194 countries
• sanctin by United Natins
• established 1988, first published report 1990
• fourth report in 2007 awarded Nobel Prize

Climate Change Consequences

• footprint in form of warming glacial retreat, earlier plant growth, greater wildfires, and rising sea levels
• magnify greenhouse effect
• vary with region

Ocean Acidification

• absorption of 30% of anthropogenic C02 increases acidity
• Carbon Acid
• current increase about 30%; predicted to double in next 40 years

Ocean acidification

Calcification

US climate change

Temp

• Temp increased 2 degrees last 50 years, projected to increase 4-10 degress by 2100

US climate change

Precipatation

Response to Climate Change

Adaptation

Response to Climate Change

Mitigation

• House bill April 2011
• Climate change is occuring
• it is cause by human actions
• poses risks to human welfare