HOW DOES SOIL FORM? GLOBE NY Metro, 2008. Why do we study soil? Because It’s A(n) Great integrator Producer and absorber of gases (CO 2 and others) Medium.

HOW DOES SOIL FORM?HOW DOES SOIL FORM?GLOBE NY Metro, 2008GLOBE NY Metro, 2008

Why do we study soil? Because It’s A(n)

Great integrator

Producer andabsorber of gases (CO2 and others)

Medium for plant growth

Medium of crop production

Home to organisms(plants, animals and others)

Waste decomposer

Snapshot of geologic, climatic, biological, and human history

Source material for construction, medicine, art, etc.

Filter of water and wastesEssential natural resource

Medium of heat andwater storage

United States Department of Agriculture

Soils are very different, depending on how they formSoils are very different, depending on how they form

5 FACTORS CONTROL THE TYPE OF SOIL 5 FACTORS CONTROL THE TYPE OF SOIL

TIMETIME is the 5th factor Soil forms by the Soil forms by the interaction of the first interaction of the first four factors. It changes four factors. It changes to create soil profiles to create soil profiles unique for the unique for the conditions and elapsed conditions and elapsed timetime. A soil profile . A soil profile consist of layers consist of layers called “soil horizons”called “soil horizons”

During the GLOBE During the GLOBE Soil Soil

Characterization Characterization protocol, you will protocol, you will describe, sample, describe, sample, and analyze soil and analyze soil

horizons near your horizons near your schoolschool

Photo courtesy, Ray Weil, PhD

Parent MaterialParent Material

TopographyTopography

ClimateClimate

Living thingsLiving things

4 factors 4 factors control soil-control soil-

forming forming processesprocesses

ROLES OF THE FIVE FACTORS OF SOIL FORMATIONROLES OF THE FIVE FACTORS OF SOIL FORMATION

Living things: Living things: Plant roots physically break rocks into small pieces; lichen dissolves rock; burrowing animals mix the soil and help aeration

TIMETIME: When bedrock is exposed at the surface, chemical, biologic, and physical processes combine to produce a thin soil layer. Over time, the processes extend vertically downward, developing soil horizons whose position and thickness change over time.

Parent materialParent material: Chemical changes during soil formation depend on what minerals and rocks are present. Example: Calcium-rich soils generally form from calcium-rich rocks (like limestone) but not from calcium-poor rocks like granite.

Topography: Loose soil stays in place in flat areas, allowing more Topography: Loose soil stays in place in flat areas, allowing more thorough physical and chemical alteration of its grains. On steep thorough physical and chemical alteration of its grains. On steep slopes, the soil moves downhill before complete alteration can occurslopes, the soil moves downhill before complete alteration can occur.

Climate: Climate: heat and water accelerate chemical changes (so moist, temperate areas like NYC have different soils than arid, tropical, or polar areas).

If all five factors are the same in two geographic regions, If all five factors are the same in two geographic regions, the soil will be the same in both. Some basic examples of the soil will be the same in both. Some basic examples of

different soil types include:different soil types include:

Temperate deciduous soilTemperate deciduous soil Coniferous forest soilConiferous forest soil Grassland soilGrassland soilConiferous forest soilConiferous forest soil

Tropical rain forest soilTropical rain forest soil Desert soilDesert soil

Soil is an excellent place to study interactions in the Soil is an excellent place to study interactions in the Earth System, including contributions from the Earth System, including contributions from the

AtmosphereAtmosphere • Dew (moisture from the air) begins chemical alteration of parent rock • Rain erodes loose soil, preventing further alteration • temperature controls rate and extent of chemical processes

HydrosphereHydrosphere • Water seeps into the ground, dissolving and redistributing elements • evaporation dries soil, changing its physical characteristics

BiosphereBiosphere • plants add and remove chemicals • plant roots anchor soil in place, enabling chemical reactions to be completed • animals mix soil; transport seeds, etc.

GeosphereGeosphere • solid rock and unconsolidated sediment are the parent material for soil • geologic processes (surface and internal) expose and bury rock, etc.

Hydrologic Cycle and the Soil

Color

Structure

Bulk Density

Texture

pH

Temperature

Soil moisture

HorizonDepths

Soil Properties related to the hydrologic cycle.