Ch. 1 Introduction to Soils
∙ 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.
∙ 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:
∙ 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
∙ 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 Salt buildup
o Loss of prime farmland to urbanization
2.2 mil acres per year 1992-1997
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.
∙ 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
∙ 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:
Study of soil properties as they relate to plant growth
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%
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
∙ Formed directly after volcano
∙ Formed from re-crystallization of weathering products of primary minerals and/or alteration of primary minerals
Some important soil forming minerals include:
KAlSi3O8, also Ca&Na
See written notes for more details on above
Classification of Rocks
∙ Rock- compromised of two or more minerals
- Volcanic in origin, contain primary minerals
o Gabbro, basalt
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
- 75% of Earth’s surface
- Deposition and recementation of rock weathering products
- Cementing agents include sandstone, limestone, shale, conglomerate
o Quartz, cementing agents Al/Fe-oxides/CaCo3 - Limestone
o Clay or mudstone
o Cemented rocks
- Sedimentary and igneous rocks changed by extreme heat and pressure
∙ 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 Forces of water, ice and wind
o Plants and Animals
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
- Reaction with water which results in the splitting of it - KAlSi3O8+H20HAlSi3O8+KOH
- Redox reactions
- Ferrous oxide Fe2+
- Ferric oxide Fe3+
- Oxygen is always O2-
- Oxidation- loss of electrons 5