Soil Science

What is the study of rocks?

Petrology

In hydrometer method, what chemical is used for dispersing the soil?

Calgon, Sodium hexametaphosphate

Aggregates of different kinds of minerals

Rocks

From Latin word ‘Ignis’ meaning Fire • Forms from solidification of hot molten material such as magma and lava • Most abundant rock in the Earth’s crust – 95%

Igneous rocks

From trapped magma, slow cooling, coarse textured

Intrusive Igneous or Plutonic

Natural relatively permanent soil aggregates

Peds

artificial formation of osil mass due to disturbances such as tillage

Clods

From lava upon rapid cooling, fast cooling, fine texture.

Extrusive igneous or volcanic

Coarse texture > intrusive igneous

Phaneritic

Fine textured > Extrusive igneous

Aphanitic

Larger crystals (phenocryst) surrounded by matrix of smaller crystall (groundmass)

Porphyritic

Forms from the compaction and cementation of sediments of pre-existing rocks such as igneous and metamorphic rock subjected to weathering

Sedimentary rocks

May also form from parts of living organisms

Bituminous coal (from plant)

collective term for step 1 to step 3 → weathering, transport, and deposition

Sedimentation

it refers to group of soil particles that bin to each other strongly than adjacent particles

Soil aggregates

collective term for step 1 to step 3 → weathering, transport, and deposition

Lithification

change in structure or composition due to heat and pressure • Form from pre-existing rocks such as igneous and sedimentary rocks subjected to heat and pressure

Metamorphic rocks

change in structure or composition due to heat and pressure

Metamorphism

Naturally occurring inorganic substance that has definite internal arrangement and definite chemical composition and physical properties

Minerals

Study of minerals concerned with structure and properties

Mineralogy

Form from crystallization of igneous rocks, source of sand and silt fractions

Primary minerals

Black mica also called?

Biotite

White mica also called?

Muscovite

Examples of extrusive igenous

Basalt, rhyolite, andesite

Example of intrusive igneous

granite, gabbro, diorite, pegmatite

What metamorphic rocks equivalent is the result?

Quartzite, marble, meta-conglomerate, slaet, schist, gneiss

Abundant elements in the earth’s crust

Oxygen 46.6%, Silicon 27.72%, Aluminum 8.13%, Iron 5%, Calcium 3.63%, Sodium 2.83%, Potassium 2.59%, Magnesium - 2.09%, Other elemetns 1.41%

Groups of soil particles that bind to each other strongly than adjacent particles.

Soil aggregate

Ability of soil to resist disruptive forces such as wind and water erosion

Aggregate stability

Common in A horizon, formation is influenced by humus, rapid water permeabilit

Granular

Major process of sedimentary rock formation

Mechanical and chemical weathering, transport of weather product, water, gravity, wind or ice, deposition of sediment and compaction and cementation.

Angular or subangular forms in the B horizon, from illuviation of clay which fills the pores, forming a block-like appearance.

Blocky

Forms in B horizon after block structure, moderate water permeability

Prismatic

Form from weathering of pre-existing mineral

Secondary Minerals

E.g of primary minerals

Olivine, pyroxene, amphibole, plagioclase, mica

e.g of secondary minerals

Pyrite, halite, kaolinite, hematite

also known as fool’s gold

Pyrite

Forms in B horizon, common in semiarid and arid regions, presence of salt cap, slow water permeability.

Columnar

Aka salt or NaCl

halite

aka Clay mineral

Kaolinite

aka oxidized iron

hematite

observable cracks caused by pressure release during uplift and erosion

exfoliation

water enters cracks and expands rock upon freezing

Freeze-thaw

cracking of rocks due to repeated expansion (high temperature) and contraction (low temperature)

Thermal expansion

collision of rocks resulting to smooth surface

abrasion

Combination of oxygen to minerals

Loss of electrons

Oxidation of magnetite to hematite

Oxidation

Forms as a result of compaction,

common in A horizon under intensive management,

very slow water permeability.

Platy

Removal of oxygen to minerals

Gain of electrons

Reduction

attack of water to minerals which causes

Change in mineral composition

Change in mineral structure

Decomposition

Hydrolysis of Kaolinite → Silt clay

Hydrolysis

Water is absorbed in the mineral structure

Does not destroy chemical structure

Hydration

Rocks or mineral with carbonic acid

Carbonation

entry of plant roots in small cracks which causes further cracks as it grows

Root wedging

Burrowing and excavation of animal, eg piddocks

Animal activity

natural body comprised of solids (minerals and organic matter), liquid, and gases that occurs on the land surface, occupies space, and is characterized by one or both of the followings: horizons or layers, that are distinguishable from the initial material as a result of additions, losses, transfers, and transformations of energy and matter or the ability to support rooted plants in a natural environment

Definition of soil, soil survey 1999

Father of Soil Science

Vasily Dokuchaev

5 Factors of Soil Formation, CLORPT

Hans Jenny

5 factors of soil formation.

Climate, Organism, Relief, Parent Materials, Time

What formation in forest soil based on the table?

Thin surface horizon (a horizon), formation of thin O horizon

Grains are not connected, lacks structure, examples are dune sand and river deposites

Single grained

Mass of soil particles with no pattern, lack structure, very slow water permeability

Massive

Test the stability of soil aggregates in water

Slake test

Fast development of soil due to high leaching and relatively less erosion as compared to backslope

Summit, shoulder

Slow development of soil due to less leaching and faster runoff causing soil erosion

Backslope

Slow development of soil due to accumulation of sediments from upslope

• Prone to flooding

Footslope and toeslope

Residual – from the bedrock

Parent material

transportation and deposition of sediments by flowing water

Alluvium

Deliberately destroying soil structure by plowing and harrowing the soil in a flooded or saturated state. Formation of impervious layer

Puddling

transportation and deposition of sediments by flowing water

What are considered cementing agents in the soil?

Lime, sesquioxides, clays

soil formation by desposition of wind transported sediments.

aeolian

bulk density increase with

increasing soil depth

bulk density is heavily related to?

Compaction

Soil accumulation transported downslope by gravity.

Colluvium

Ratio of mass of soil solids to the volume of soil.

Bulk density.

deposition of soil material from melting ice

Glacial drift

Includes processes and conditions by which initial materials are differentiated into soil profiles with many horizons

Horizonation

Includes processes and conditions by which horizonation is inhibited or decelerated or by which horizons are mixed or disturbed

Haploidization, erosion and pedoturbation

Simonson’s model

Soil = f(a,r,t1,t2)

general term for any material added to soil body

Enrichment

darkening of light colored mineral by admixture of organic matter

Melanization

aeolian, hydrologic, and man-made additions of mineral particles to the surface of a soil solum

Cumulization

accumulation on the mineral soil surface of organic litter and associated humus to a depth of less than 30cm

Littering

Standard of particle density (mineral soils)

2.65 g/cm3

removal of material from the surface layer of a soil

Erosion

general term for washing out or eluviating soluble materials from the solum

Leaching

breakdown of mineral and organic materials

Decomposition

formation of new particles of mineral and organic species

Synthesis

release of minerals components (inorganic) of organic matter through decomposition

Mineralization

transformation of raw organic materials into humus

Humification

chemical, biological, and physical changes in organic soil after air penetrates previously waterlogged soil

Ripening

increase in volume of voids by activity of plants, animals, and humans and by freeze-thaw or other physical processes and by removal of material by leaching

Loosening

decrease in volume of voids by collapse and compaction and by filling of some voids with fine earth, carbonates, silica, and other materials

Hardening

accumulation of soluble salts such as sulfates and chlorides of calcium, magnesium, sodium, and potassium in salty (salic) horizons

Salinization

accumulation of sodium ions on the exchange sites in a soil

Alkalization/ Solonization

leaching of sodium ions and salts from nitric horizons

dealkalization/ solodization

chemical migration of aluminum and iron and/or organic matter, resulting in concentration of silica in the layer eluviated

Podzolization / Silication

chemical migration of silica out of the soil solum and thus the concentration sesquioxides in the solum

Laterization / Desilication

release of iron from primary minerals and the dispersion of particles of iron oxide in increasing amounts; their progressive oxidation or hydration, giving the soil mass brownish, reddish brown, and red colors, respectively

Braunification, Rubification, Ferrugination

reduction of iron under anaerobic “waterlogged” soil conditions, with the production of bluish to greenish gray matrix colors, with or without yellowish brown, brown, and black mottles, and ferric and manganiferous concretions

Gleization

washing in suspension of fine clay down cracks and other voids in a soil body

Lessivage