Unit 2 Topic 2 soil. What is soil and why do we care about it? complex mixture: weathered mineral materials from rocks partially decomposed organic.

Unit 2 Topic 2Unit 2 Topic 2

soilsoil

What is soil and why do we care about it?What is soil and why do we care about it?

complex mixture: weathered mineral

materials from rocks partially decomposed

organic molecules Ecosystem services

complex mixture: weathered mineral

materials from rocks partially decomposed

organic molecules Ecosystem services

Soil formationSoil formation Many factors contribute to this LONG process

Parent material, Time, Topography, Climate, Organisms Help determine soil type

Many factors contribute to this LONG process Parent material, Time, Topography, Climate, Organisms

Help determine soil type

Soil Texture Soil Texture Ratio of soil particle size determines some soil

properties Ratio of soil particle size determines some soil

properties

Determining soil typeDetermining soil type

% Increasing Clay

Soil Properties: Porosity Soil Properties: Porosity Affects water infiltration, water holding capacity,

aeration, workability Affects water infiltration, water holding capacity,

aeration, workability

Soil Properties: Chemical Soil Properties: Chemical Cation exchange capacity (aka nutrient holding

capacity) Base saturation

Cation exchange capacity (aka nutrient holding capacity)

Base saturation

SOIL ProfileSOIL Profile

Weak humus-mineral mixture

Mosaicof closelypackedpebbles,boulders

Dry, brown toreddish-brown, with variable accumulationsof clay, calciumcarbonate, andsoluble salts

Desert Soil(hot, dry climate)

Grassland Soil(semiarid climate)

Alkaline,dark,and richin humus

Clay,calciumcompounds

Soil Profiles in Different Biomes

Soil Profiles in Different Biomes

aridisolsmollisols

Acidiclight-coloredhumus

Iron andaluminumcompoundsmixed withclay

Forest litterleaf mold

Humus-mineralmixture

Light, grayish-brown, silt loam

Dark brownfirm clay

Tropical Rain Forest Soil(humid, tropical climate)

Deciduous Forest Soil(humid, mild climate)

Soil Profiles in Different Biomes

Soil Profiles in Different Biomes

oxisols alfisols

Soil Properties: Biotic

Soil Properties: Biotic

surface = algae top few cm of soil =

bacteria & fungi roundworms, segmented

worms, mites, insects farther down: burrowing

animals--gophers, moles, insect larvae, worms

even farther: some plant roots

surface = algae top few cm of soil =

bacteria & fungi roundworms, segmented

worms, mites, insects farther down: burrowing

animals--gophers, moles, insect larvae, worms

even farther: some plant roots

Soil CommunitySoil Community

Soil Community -- Mycorrhizae

Soil Community -- Mycorrhizae

Redwood seedlings with (right) and without (left) mycorrhizae.

Pine seedling showing how mycorrhizal roots from one tree spread to inoculate other tree roots.

mycorrhizal symbiosis - mutualism between plant roots & fungi

Soil degradation and loss

Soil degradation and loss

Soil conservation and improvementSoil conservation and improvement

Organic vs. inorganic fertilizers

Sustainable agriculture practices

Erosion control

Organic vs. inorganic fertilizers

Sustainable agriculture practices

Erosion control