SOIL

"And the Lord God formed man of dust (soil) from the ground…And out of the ground the Lord God formed every beast… bird" Gen. 1:2-7

Define Soil

- The upper layer or layers of the earth in which fine rock particles and organic material provide the basis for plant life.

- The thin surface layer of mineral and organic matter (containing living matter) that support plant life.

- Or simply that portion of the earth's surface that can support plant life.

Why do we have different soils? Soil characteristics are derived from prevailing climate, through infusions of heat energy and water and from interactions with organisms that live within.

5 major environmental factors in soil formation

S = f(CROP)T² (climate, relief, organism, parent material) time

Different, complex - physical, chemical processes operate simultaneously within the soil

Polypedon - smallest distinctive division of the soil in a given area.

Pedon - soil column extending down from the surface to reach the lower limit in regolith or bedrock. A 3-D representation of soil profile.

Soil profile - display of horizons or one face of the pedon.

Solum (A and B horizons)

Soil components 4: mineral fraction, organic matter, soil water (hygroscopic, capillary, gravity0, and soil air

Soils evolve from parent rock materials to mature soils, distinct layers - soil horizons a well developed soil has 3 distinct horizons. Differ in:

- color

- Texture

- Structure

- Porosity

- Chemistry

Soil Color - .....................................................

black - indicates presence of organic matter

red - indicates presence of iron compounds

Texture - size grades. (Sand, Silt, and clay) Gravel?

2mm - gravel

0.05 - sand

.002 - silt

< 0.002mm -clay

Loam - mixture containing a substantial proportion of each of the three grades classified as sandy, silty or clay-rich when one of the grades is dominant.

Texture - largely determines the ability of the soil to retain water or to transmit water to the intermediate belt below.

Storage capacity -

How sand transmits water rapidly and clay most slowly

Sand reaches capacity very rapidly (in planning irrigation)

Parent minerals of soil

1^st degree and 2^nd degree minerals

clay ( 2^nd degree mineral)

Montmorillonite - can hold base .....High Fertility

Kaolinite - holds few base ions

Illite - intermediate

Humus - High

Mineral oxides - alteration products of clay? Several thousand of years. E.g. Al and Fe

Limonite and Bauxite - associated in soil of warm, moist climates in low latitude - They have large capacity to hold base ions.

Structure - ways in which soil grains are grouped together into bigger masses (shape of particles) called peds --- range in size from small grains to large blocks.

Granular,

Crumby structure,

Columnal,

Prismatic,

Platy,

Blocky

Ease of tilling depends on the soil structure.

Soil-forming Processes

Soil horizons are developed by the interactions through time of climate, living organisms and the configuration of land surface.

Horizons are usually explained by either selective removal or accumulation of certain minerals, colloids and chemical compounds. Translocations of minerals---elluviation and illuviation.

Downward transport process - Elluviation

Calcium carbonate (Calcite

Decalcification - removal of CaCO3 for soil… occurs in humid and dry

environments

Calcrete - C horizon - rock like layer

Salinization - desert climate

Salic horizon - a zone with high NaCl

Soil Forming processes or Pedogenic regimes

Podzolization High precipitation low temperature

Laterization High precipitation and high temperature

Calcification Mild temperature and mild precipitation

Gleization Low temperature high precipitation

Salinization High temperature and low precipitation

Sketch of Temp vs. Precipitation

Soil - water balance and soil temperature are important factors in soil formation including biological processes and Man.

Soil texture is largely an inherited feature of a given soil and depends on the composition of the parent matter.

Wilting point - a measure of soil - water storage

Colloids-particles smaller than 0.1u-inorganic colloids play vital role in soil -how?

Humus-finely divided, partially decomposed organic matter found resting on the soil surface & mixed through the upper horizons. These particles give soil brown or black coloration.

Ions in soil - e.g. NaCl dissolves to produce Na + and Cl - ions

Colloids of mineral origin have - we enter surfaces

Base cations - Ca, Mg, K and Na very useful to pits held by colloids but are released to pits.

The colloids make the ions available to pits which have normally been lost through leaching.

Acidity and Alkalinity - Presence of H and Al - acid

Base cations tend to make the soil alkaline

Increase of cations - soil acidity increases. Cations replaces in soil making the soil less fertile.

The degree of acidity or alkalinity of is designated by pH number.

High soil acidity is typical of cold humid climates

High soil alkalinity is typical of dry climates.

Global Scope of Soils

Factor of climate

Parent material

Time are linked with the distribution of

Biological process types of soil

Fertility of soil + available water = measure of the capability of an environmental region to produce food for the human race.

Classification of soils

Six categories or levels

1^st level - soil orders - (11)

2^nd level - sub orders - (47)

3^rd level - Great groups (185)

Soil orders and suborder can be distinguished on basis of the presence of diagnostic horizon. Each has some unique combination of physical properties (color, structure, texture) Chemical (minerals present of absent)

2 basic kinds of diagnostic horizons

- A horizon formed by removal or accumulation of matter.

Based on overall properties and history of development the 10 orders can be grouped into 3 classes.

I. Soils with well- developed horizons or with fully weathered minerals, resulting from long- continued adjustment to the prevailing soil- temp. and soil- water regions.

Oxisols - Heavy leaching.... tropics/equatorial

- V. old, highly W soils of low Lat. With subsurface horizon of accumulated mineral oxides (red, yellow)

-Ultisols - red and yellow brown

Soils of equatorial tropical and subtropical lat. With subsurface horizon of clay acc. And low base wide cracks
Vertisols - Soils of Subtropical and tropical zones with high clay contact and high base status developing deep (Brown)

Alfisols - Some leaching clay accumulation in B zone. Sub humid climates with subsurface H of C accumulation and high base

Spodosols - S cold moist climate with well developed B horizon and low base (Brown. White., yellow)

Mollisols - Sometimes called Chernozem, Prairie etc. Semiarid and Subhumid mid latitude.
Grassland with a dark, humus-rich Epipedon and very h base ( brown yellowish color)

Aridisols - Horizon poorly developed or absent. -S dry climates, low in org. matter and high subsurface H of arc of CO3 minerals and soluble salts (white, brown colors)

VII. Soils with large proportion of organic matter

Histosols - S with thick upper layer very rich in organic matter....originally called bug soils horizons poorly developed (black, brown)

VIII. Soils with poorly developed horizons or and capable of further mineral weathering

Entisols - youthful soils

-Soils lacking horizons usually because of occurrence of parent matter Alluvial sand dunes

Inceptisols - young cells

-Soils with weakly developed horizons having minerals that are capable of further alteration by weathering processes

Important of River flood plain and delta plains Volcanic ash deposit

Gellisols ... permafrost or extremely cold soils

Old soils - Seven soil orders consist of soils with well developed horizons or with fully weathered minerals. They are old with a large history of development, well adjusted to preventing soil temperature and soil water conditions.

Organic soils - one soil order that is characterized by a thick upper layer of organic matter called peat.

Young soil - two orders have poorly developed horizons or no horizons, they are young soils, not yet well adapted to the environment.

Base status - Soils differ greatly in natural fertility.

Fertile soils have high base status.

Poor soils have low base status.

Soil order- Classes II and III are geologically controlled by local occurrences of features, such as flood plains, recent deposits left by glaciers, acres of sand dunes, marshlands or bogs.

In low latitudes, Ultisols are identified with the wet-dry tropical climate and the monsoon and trade-wind littoral zones.

Oxisols and Ultisols can only sustain crops on freshly cleared areas for only 2 to 3 years at most before the nutrient bases are exhausted. Use of lime and fertilizers are necessary for high sustainable crop yields.

Vertisols formed under grass and savanna vegetation - subtropical and tropical climate with a pronounced seasonal soil-water shortage.

High in base status and are particularly rich in such nutrients bases on Ca and Mg

SOILS AND HUMAN WELFARE Soil mismanagement

Soil erosion - natural but can be accelerated by man through ? ask class

Wind, landslide, gully erosion

Prevention - soil reclamation

-tree/grass planting

-check dam?

-Strip-cropping

LAND FORM, INTERIOR OF THE EARTH, AND EARTH MATERIALS

General structure of the earth: Crust (8-40 km), Mantle (2900 km), and Core (3500 km).

Structure and composition of the earth

Mohorovicic Discontinuity (MOHO)

Continental drift and sea-floor spreading hypothesis…Alfred Wegener….Henry Hess

Pangea --- Gongwana land and Eurasia

A combination of the two hypothesis gave rise to the Plate Tectonic Theory

Lithosphere… 8 giant plates and lesser plates

Plate Boundaries…spreading (divergent), coming together (convergent0, and sliding past one another (transform)

Lithosphere- includes the crust and 1^st 100 km of mantle

Asthenosphere- Next 100 km and the rest called Mesosphere-

Upper mantle. Crust- continental and oceanic

Solid realm of planet earth- inorganic and organic

Continents- Landforms (surface configuration) - Sial (Granite)

Oceans- 71% of earths surface - Sima (Basalt) - Magnesium

Composition- Earths crust (~17 Km) continent and oceans, source of soil, sediments vital to life, salts of the sea, gases of atmosphere, H2O.

Composition: Oxygen (47%), Silicon (28%) form 75% of the crustal minerals. Other minerals are, Aluminum, Iron, Calcium, Sodium, Potassium, Magnesium, Titanium H, P Ba, St Point out the significance

Rocks and Minerals

A Mineral is a naturally occurring inorganic substance, usually possessing a definite chemical composition and characteristic atomic structure. There are over 2000 known minerals. Rock forming minerals are few >90% of the rock forming minerals belong the silicate group of minerals.

Rocks are aggregate of minerals in the solid state (compound) (there are rocks that are composed of one mineral type).

Classes (3 major)

1. Igneous (High temperature, molten)

2. Metamorphic (Physical and chemically changed (Igneous and Sedimentary))

3. Sedimentary (layered accumulated of mineral particles.)

Silicate Minerals- Bulk of Igneous Rocks consists of

silicate minerals.

1. Examples of silicate group of minerals:

2. Quartz (silicon dioxide)

3. Feldspar- Potash feldspar or K (Potassium and Aluminum)

Plagioclase feldspar (sodium, calcium)

13. Mica group (eg Biotite, Muscovite)

14. Amphibole (Hornblende

15. Pyroxene (Augite) Mafic (dark) minerals

16. Olivine (Mg and Fe silicate)

Other mineral Groups

1. Carbonates e.g. Calcite, Dolomite

2. Sulfides e.g. Galena, pyrite, chalcopyrite, sphalerite

3. Oxides e.g. Hematite, magnetite, corundum

4. Sulfates e.g. Gypsum, anhydrite

5. Native, Cu, Au, Ag

6. Phosphate, Apatite

7. Halides, Halite, Flourite

Some physical mineral properties
Color, Streak, Luster, Hardness, Density,Crystalline form, Fracture, Cleavage, etc.

Rocks...definition ( visit IPFW geogarden )

Igneous Rocks- are rocks that are produced from molten rock called magma (or lava when they are at the land surface).

Brief discuss Magma and how igneous rocks are formed

Job. 12:8 "Speak to the earth and it shall teach thee…" Translation….ask the rocks questions and they will answer you.

Types

1. Granite (Quartz, potash feldspar, plagioclase, biotite, amphibole)

2. Diorite (No quartz) more of plagioclase

3. Gabbro (Dominant mineral is pyroxene followed by plagioclase

4. Peridotite (olivine ~ 60% , pyroxene 40%)

Plutons (intrusive (Plutonic rocks))

1. Batholiths (several kilometers deep and several thousands square km)

2. Sill === Plate

3. Dike // Wall like

4. Stock

5. Laccolith

6. Lopolith

Extrusive Igneous rocks (lava) quick cooling (illustrate with obsidian)

Rhyolite- Pale grayish or pink color - similar to granite

Andensite- Pale grayish or pink color - similar to diorite

Basalt- black - similar to gabbro

Metamorphic Rocks- Alterations of Igneous as fed by tremendous pressures and high temperatures that accompany Mt. Building movement fo the earths crust

Shale - slate- Schists

Sandstone - Quartzite

Limestone - Marble (sugary texture) GNEISS

Sedimentary Rocks

Origin - Igneous, Met and also from other Sedimentary rocks

Sediments - Broken pieces of minerals/rocks carried in fluid - air, water, ice.

3 classes

1. Clastic

sorting determines texture

13. Chemically precipitated sediments - Sea water or hard parts of once living organisms. E.g. rock salt, lime

14. Organic sediments - tissues of plants/animals. E.g. peat in a bog

Layering nature STRATA

Clastic Sedimentary rocks

1. Sandstone

2. Mudstone (Mud - silt and clay with some sand grains

3. CLAYSTONE

4. SHALE (from mud) -

5. Clay minerals: kaolinite, illite, montmorillonite

Why is quartz an important clastic sediments?

Carbonate Rocks

1. Limestone (largely calcite (caCO3)

2. Dolomite (Ca(Mg)CO3 Chalk-pure white rk is from skeleton of marine algae. Reef 1^st from corals

3. Chert (silicon dioxide non-crystalline) also occurs with 1^stChemical

4. Phosphate

5. Evaporites (Rock salt) (Halite - sodium chloride)

Peat- soft fibrous substance of brown-black color accumulates in bog Coal

Petroleum (crude oil) oil shale

Natural gas Kerogen (waxy)

Bitumen (thick log)

Clastic, Organic, chemical, evaporite (Major classes of sedimentary rocks)

ROCK CYCLE

Igneous rocks (melting)

(melting, weathering) (melting, High temp./pressure)

(weathering) Sedimentary (weathering, HT/HP) Metamorphic (HT/HP)

Structures

Folds…. Anticline, syncline , simple fold, isoclinal, overturn, recumbent

Domes and basins

Faults…..Normal, reverse, trust, strike-slip

Joints

Unconformity

Weathering and Mass wasting

Processes that cause rocks to disintegrate physically and decompose chemically because they are exposed at or near the earth's surface.

Regolith- products of Lt. Weathering - sources for sediment consist of detached minerals.

Disintegration and decomposition of various kinds of hard bedrock greatly facilitate the erosion of land surface by water.

Weathering leads to a number of distinctive landforms.

Agitations in the soil and regolith because of changes in temperature and water content (Daily and seasonal changes)

Spontaneous downhill movement of soil, regolith and rock, under the influence of gravity (No fluid involved) is known as wasting.

Slope- Inclined land surface from the horizon (Guides flow of surface water)

Physical (Mechanical) Weathering (More effective in cold dry climates)

1. Frost action- Tundra climate of arctic coast

Talus slopes (fragments)

Stone rigs (in tundra region sorting)

Ice-wedge polygons

2. Salt (in dry environments) salt crystals

3. Unloading (through erosion) Sheeting structure esp. in granitic rocks.

Exfoliation dome At smaller scale have spheriodal weathering - this due to chemical weathering.

4. Vegetation- similar to the Heat/cool cycle

5. Heating and cooling cycle

Chemical Weather (warm wet climates)

Hydration 1. Mineral alteration (ion exchange)

Hydrolysis 2. Oxidation - the combination of oxygen with metallic accompanies hydrolysis

Oxidation 3. Carbonic acid action - limestone. Caverns. Karst landscape, also know as solution weathering

Carbonation 4. Hydrolysis - potash feldspar. - Kaolinite

Solution Product clay. Bauxite (warm climate) from plagioclase Feldspar

Mass Wasting

Landslides from USGS website.
Pictorial representation of mass wasting types. Which one is a slump and which is a slide according to the clas lecture?

Landside Types and Processes