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MSU / Soil Science / PSS 3303 / Why humanity depends on soil?

Why humanity depends on soil?

Why humanity depends on soil?


School: Mississippi State University
Department: Soil Science
Course: Soils
Professor: Jac varco
Term: Fall 2016
Tags: soils
Cost: 25
Name: Soils Ch. 1 and 2
Description: These notes cover the material that will be on quiz 1,2, and 3. Also this is part of the material on test 1.
Uploaded: 09/07/2016
11 Pages 43 Views 2 Unlocks

Ch. 1 Introduction to Soils  

Why humanity depends on soil?

∙ What is Soil?  

o Humanity depends on it

o Natural medium for plant growth  

o Foundation of our existence  

∙ Why Study it?  

o See above

∙ You’ll discover… what lives in soil, and how soil helps  things to live/thrive.

Interdisciplinary Science  

∙ Soil depends on many other sciences  

o Biology, Microbiology, Plant Physiology, Soil Animals o Physics, Hydrology, Water, Temp  

o Geology, Mineralogy, Weathering, Sedimentation  o Chem, Biochem  

Earth- Our Home  

∙ Life Sustaining Properties:  

o Atmosphere  

o Water  

o Soil  

When was the science of forest soils began?

∙ Supports a US pop of 324 mil. and world pop of > 7.34 bil.


∙ Ecosystem services- doing things for the benefit of  improving the habitat or ecosystem

∙ Soil- Top layer of the earth’s surface suitable for plant  growth. Also, land, to make dirty (soiled), animal feed.  

∙ Dirt- Earth or soil, also filthy with soil, dust excrement etc.  Humanity depends on soil:  

∙ To produce food, feed, fiber, wood and biofuel

∙ Soil supplies water, air, nutrients, temp, moderation, and  support for plant life  

∙ Construction of homes, buildings, roads and recreational  areas.  

o Firm stable soil is critical in construction  

Soil is a natural entity of unconsolidated organic?

∙ To dispose of waste  We also discuss several other topics like What do anions gain?

o Soil serves as a filter for groundwater, a  

decomposer and storage

∙ As a component of our environment.  

o Gas and water exchange

o Supports microbial and animal life  

∙ “The quality of life is directly related to soil quality.” – Dr.  Jac J. Varco  Don't forget about the age old question of What are the essential polysaccharides in the living world?



∙ 0.66% of US pop are principle farmers  

∙ Expanded economy in manufacturing and service  ∙ Miss. Acreage Data  

o Total acres= 30 mil

o MS Delta=5 mil acres  

o 1 crop soybean= 2 mil  

∙ Land use  

o Urban 2.68%  

o Cropland 18%  

o Parks 11.1%

o Pasture 27%  

o Forest 29.7%  

Demand on Land Resources  

∙ Population increase- demand for food, feed, fiber, and  timber increases  

∙ Potential Biofuel production  

∙ Yields per acre have increased but how high can they go?  

∙ Acreage that could be brought into production includes  marginal land, wetlands, forest and arid soils.  

∙ Soils exploited in the past in terms of fertility and erosion

∙ Proper soil management is imperative to maintain  productivity.  

∙ Crop productivity and sales represent and infusion of  money and economy  

∙ Soil History:  We also discuss several other topics like Neurogenesis is the formation of what?

o Soil destruction or mismanagement-contributed to  downfall of some civilizations  


o For example, Mesopotamia-overcrowding-pollutions  and irrigations

∙ Potential Problems in the US include:  

o Erosion  

o Salt buildup  

o Loss of prime farmland to urbanization  

 2.2 mil acres per year 1992-1997  

o Pollution

o Declining Fertility  

∙ Early Soil Concepts

o Romans and Greeks observed soil-plant  


o Early soil science (1563-1850) developed linkage  between manures, legumes and soil and plant  nutrition.  

Soil Scientists  

∙ Two individuals responsible for recognizing soil as an  organized body; an entity which evolves and depends on  various factors  

∙ EW Hilgard If you want to learn more check out In psychology, graded potential used to describe what?
If you want to learn more check out What are the contemporary concepts of a family?

o State geologist of MS, recognized relationships  between climate, vegetation, and rock materials  and soils which develop  

o Father of Soil Science  

o MS  

∙ VV Dukochaev  


o Russian scientist who described horizonation and  soils or natural bodies  

o Responsible for developing a system of soil  classification around 1883

∙ Late 19th Century: the science of forest soils began  ∙ Early texts published 1946 and 1958 Don't forget about the age old question of In biology, what is a polypeptide chain?

∙ 1979-1st edition Forest Soils: Properties and Processes  ∙ Two approaches exist for studying soils:  

o Edaphology  

 Study of soil properties as they relate to plant  growth  

o Pedology

 Study of soils as a natural body and how  

environmental factors affect the classification

∙ Soil is a natural entity of unconsolidated organic and  inorganic constituents in dynamic equilibrium with its  environment and serves as a medium for plant growth

o Sand,Silt, and Clay

Soil as an Organized Body

A. Soil Horizon  

- A distinct zone or layer formed by soil  

forming processes and having distinct  

characteristics such as texture, color and  


B. Soil Profile  

- Horizons which make up a soil at a given  


∙ Sollum-upper-most weathered material  

∙ Regolith- unconsolidated materials above bedrock 5

o Red Soil: iron oxide  

∙ Soil Composition by Volume:  o Organic matter 5%

o Mineral 45%  

o Water 20-30%

o Air 20-30%

∙ Soil Composition by Weight:  o Mineral Water-77%

o Organic Matter-3%

o Water-varies  


Ch. 2 Formation of Soils from Parent Materials

Formation of Soils from Parent Materials

∙ Soil- derived from weathered products of rocks and  minerals  

∙ Physical and chemical decomposition or rocks and  minerals= inorganic unconsolidated sediments  Soil formed  

∙ Directly from weathering of rocks in situ

∙ Or, from sediments deposited by geological processes.  ∙ Mississippi?  

∙ Weathered materials=parent material of soil inorganic  fraction, organic debris or detritus serves as parent  material for organic fraction.  


∙ Determine origin of soil mineral and organic fractions  and processes which alter physical and chemical  properties of geological materials to produce it.  

Minerals and Rocks

∙ Mineral-Inorganic substances formed through geological  processes which have a fairly definite chemical  composition and display uniform physical properties  

∙ Minerals can be classified as being primary or secondary ∙ Rocks: bunch of minerals  

Primary Minerals  

∙ Formed directly after volcano  

Secondary Minerals

∙ Formed from re-crystallization of weathering products of  primary minerals and/or alteration of primary minerals

Some important soil forming minerals include:  

Mineral Name




KAlSi3O8, also Ca&Na
























Ca2(Al,Fe)4(Mg,Fe)4Si6 O24


See written notes for more details on above

Classification of Rocks

∙ Rock- compromised of two or more minerals  

A. Igneous  

- Volcanic in origin, contain primary minerals  

o Granite  

o Diorite  

o Gabbro, basalt  

- Granite  

o Quartz, feldspar, mic and possibly apatite  

o Acidic in nature can form loam to clay loam soils - Diorite  

o Low quartz  

o Higher in feldspar and muscovite  

- Gabbro, basalt  

o Dark minerals such as augite and biotite, or ferro magnesium  


o Basic in nature, more easily weathered  

B. Sedimentary

- 75% of Earth’s surface  

- Deposition and recementation of rock weathering  products  

- Cementing agents include sandstone, limestone,  shale, conglomerate  

- Sandstone  

o Quartz, cementing agents Al/Fe-oxides/CaCo3 - Limestone  

o Calcite  

o Dolomite  

- Shale

o Clay or mudstone  

- Conglomerate  

o Cemented rocks  

C. Metamorphic  

- Sedimentary and igneous rocks changed by extreme  heat and pressure  

o LimestoneMarble  

o ShaleSlate

o GraniteGneiss

o MicaSchist

o SandstoneQuartzite  

∙ Physical disintegration and chemical decomposition  (weathering) results in:  

o Release of essential plant nurtrients  

o Formation of secondary clay minerals  

o Concentration of resistant minerals  

∙ Geochemical Weathering  

o Weathering reactions taking place in rock and  unconsolidated parent material  

∙ Pedochemical Weathering  


o Weathering within a soil profile  

1. Physical Weathering  

o Temperature

o Forces of water, ice and wind  

o Plants and Animals  

∙ Temperature  

o Freezing and thawing  

o Differential heating and cooling of rocks, exfoliation  ∙ Forces of water, ice and wind  

o Water-rounded gravel, sand grain etc. abrasive  action of water movement loaded with sediments  o Ice-erosive forces, abrasion, transport, detachment  o Wind-abrasive action, transport  

∙ Plants and Animals  

o Plants and animals have little consequence  

o Splitting of rocks by roots  

2. Chemical Weathering  

o Chemical or mineralogical composition of the  original rocks and minerals is altered

∙ Chemical Weathering- geological agents water and  oxygen, as well as biological agents such as acid  produced by microbial and plant-root

∙ Biogeochemical Weathering- convert primary minerals  (e.g. Feldspars and micas) to secondary minerals (e.g.  clay and carbonates) and release elements in soluble  forms including plant nutrients  

1. Hydrolis

- Reaction with water which results in the splitting of it  - KAlSi3O8+H20HAlSi3O8+KOH

2. Oxidation

- Reduction  

- Redox reactions  

- 4FeO+O2Fe2O3

- Ferrous oxide Fe2+

- Ferric oxide Fe3+  


- Oxygen is always O2-

- Oxidation- loss of electrons  5

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