Lithosphere Ecology lecture notes KVB

Page 1: Lithosphere

Overview

  • Earth is a cooled, spherical, solid planet that rotates on its axis and revolves around the Sun.

  • The solid component of the Earth is called the lithosphere.

  • The lithosphere consists of multiple layers:

    • Crust: Outermost layer, approximately 8 to 40 km thick.

    • Mantle: Extends about 2900 km above the core, in a molten state.

    • Core: Central fluid sphere made primarily of Nickel-Iron, with a diameter of about 2500 km.

Soil Science

  • The study of soil is known as Soil Science, Pedology, or Edaphology.

  • Soil supports rich biological communities, providing food, shelter, and protection from predators.

Page 2: Soil Formation and Types of Rocks

Rock Types

  1. Igneous Rocks: Formed from cooling of molten magma or lava (e.g., granite, basalt).

  2. Sedimentary Rocks: Formed from deposition of weathered minerals from igneous rocks (e.g., sandstone, limestone).

  3. Metamorphic Rocks: Formed by changing existing rocks through heat and pressure (e.g., marble, gneiss).

Weathering Processes

  • Physical: Temperature, ice, gravity, water, wind.

  • Chemical: Solution, hydrolysis, oxidation, carbonation, hydration.

  • Biological: Involvement of organisms like lichens and mosses that aid in rock weathering and nutrient extraction.

Page 3: Chemistry of Soil Minerals

Minerals in Rocks

  • Rocks are a chemical mixture of different minerals that form the basis of soil chemistry.

Page 4: Examples of Different Rock Types

Igneous Rocks:

  • Basalt, Pumice, Obsidian, Rhyolite, Granite.

Metamorphic Rocks:

  • Marble, Gneiss, Anthracite, Schist.

Sedimentary Rocks:

  • Bituminous coal, Chalk, Limestone, Sandstone, Rock salt.

Page 5: Structure of Soil

Soil Layers

  1. O Horizon: Composed of organic material like leaves and twigs.

  2. A Horizon: Contains partially decomposed organic matter (humus) and mineral particles.

  3. B Horizon: Subsoil with less organic material than A Horizon.

  4. C Horizon: Weathered parent material without organic materials.

  • Soil layers influence water storage and nutrient recycling.

Page 6: Soil Morphology

Soil Texture

  1. Coarse textured soils: Sandy, low moisture retention.

  2. Moderately coarse soils: Sandy loam.

  3. Medium textured soils: Mixture of sand, silt, clay for good water retention.

  4. Moderately fine textured soils: High clay content, sticky when wet.

  5. Fine textured soils: High clay percentage, hold considerable water.

Page 7: Soil Colour

Colour Variations

  • Inherited from parent material or shaped by soil-forming processes.

  • Red/yellow from iron oxides; darker soils indicate higher organic matter.

  • Soil colour can indicate drainage status and organic content.

Page 8: Physical Properties of Soil

  1. Soil Density: Average density is 2.65 g/cm³.

  2. Porosity: Spaces between soil particles (micro-pore and macro-pore spaces).

  3. Permeability: Movement of water through pore spaces.

  4. Soil Temperature: Affected by solar radiation and decomposition processes.

  5. Soil Water: Essential for life, exists in different forms (gravitational, capillary, hygroscopic).

Page 9: Soil Overview (Visual)

  • Various soil types classified by porosity and permeability.

Page 10: Soil Atmosphere and Solution

Soil Atmosphere

  • Contains gases like O2, CO2, and N2, richer in moisture and CO2 than atmospheric air.

Soil Solution

  • Weak solution of salts, essential for nutrient availability and soil chemistry.

  • Nutrient concentrations categorize soils as eutrophic (optimal) or oligotrophic (suboptimal).

Page 11: Chemical Properties of Soil

  1. Inorganic Elements: Includes Al, Si, Ca, Mg, Fe, K, Na, and trace elements.

  2. Organic Matter: Humus as a major component, rich in various organic compounds.

  3. Colloidal Properties: Exhibit properties like absorption, coagulation.

  4. Soil pH: Ranges from acidic to basic, crucial for chemical reactions in soil.

Page 12: Soil Fauna and Flora

Microfauna

  • Examples: Protozoa, small mites, nematodes.

Microflora

  • Nutrient recycling through bacteria, fungi, actinomycetes, and algae; dominance of bacteria.

Page 13: Soil Biota

Mesofauna

  • Includes small arthropods, larger nematodes, and soil invertebrates.

Macrofauna

  • Larger organisms like earthworms and insects, crucial for soil structure and nutrient cycling.