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SOILS
Station Master
Brian Zimmerman, Nassau County SWCD
516-364-5860 email
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Learning Objectives
This section provides a framework of principal soils topics. It may help to organize your knowledge into categories
such as these while preparing for the contest. See the textbook for more complete information. The last section
contains supplementary material on the subject of hydric soils.
I. SOIL CONCEPTS
A. Definition of soil -- There can be many uses of the word "soil",
depending upon the context. For example, soil can be thought of as an engineering material for road construction,
as dirt on clothing, as a mixture of ingredients for growing potted plants, or what the farmers plow every spring.
For the purposes of the Envirothon, "soil" is defined as it is in the textbook (Soil Science Simplified,
1997): "Soil is the collection of natural bodies on the earth's surface, in places modified or even made by
man of earthy materials, containing living matter and supporting or capable of supporting plants out-of-doors."
Soil is thus considered both a product of nature and a critical part of natural systems. This definition also allows
soils to be collectively grouped into a classification system, as used in making soil surveys.
B. Soil development -- a process that occurs over time.
1. Soils "begin" as parent material, then the process of weathering
occurs.
2. Weathering eventually causes a differentiation into distinct horizons.
3. A soil and its profile show the effects of five soil-forming factors: Climate, Living Organisms, Topographic
Relief, Parent material and Time (it may help to remember the word "CLORPT"). Soils can be considered
as "young", "mature" or "old", depending upon their extent of weathering and horizon
development. Soils in NY State are relatively young or mature, but not old -- their parent material was exposed
or deposited during the relatively recent retreat of glaciers, some 10 to 15 thousand years ago.
II. SOIL CHARACTERISTICS
A. Composition -- About a 50%-50% mix of solids and open space; voids
may hold water or air.
B. Texture -- refers to soil particle size, sand = 2 to 0.05 mm; silt = 0.05 to 0.002 mm; clay = <0.002 mm.
Soil texture influences water storage & movement, fertility, and workability or "tilth". "Loam"
is a name for one of various mixtures of these three particle sizes.
C. Structure -- the arrangement of soil particles into aggregates, which may have various shapes, sizes and degrees
of development or expression. Soil structure influences aeration, water movement, erosion resistance, and root
penetration.
D. Slope -- the inclination of the ground surface. Slope influences runoff of rainfall, soil erosion, stability,
and machinery operation.
E. Color -- Soil color often indicates soil moisture status and is used for determining hydric soils. Often described
using general terms, such as dark brown, yellowish brown, etc., soil colors are also described more technically
by using Munsell soil color charts, which separate color into components of hue (relation to red, yellow and blue),
value (lightness or darkness) and chroma (paleness or strength).
F. Chemistry -- A complex subject within soil science; the most important subjects are:
pH -- The acidity or alkalinity of soils, which affects plant growth and soil fertility.
G. The soil profile -- A vertical cut that exposes soil layering or horizons. Horizons are formed by combined biological,
chemical and physical alterations. A, B, and C symbols are used to describe the topsoil, subsoil and substratum,
respectively.
H. Permeability -- The ability of a soil to transmit water or air. Faster or greater permeability often occurs
in sandy or gravelly soils due to large pore spaces. Slower permeability typically occurs in finer textured clay
soils, or compacted soils with little structure.
I. Drainage -- The rate in which water is removed from a soil. Drainage influences most uses of soils, whether
for agriculture, silviculture or urban. Classes of soil drainage are those found in soil survey reports, such as
well drained, moderately well drained, somewhat poorly drained, poorly drained, and very poorly drained. Soil color
patterns (such as mottle patterns or redoximorphic features) often indicate soil drainage class. Most productive
agricultural soils in NY are well drained or moderately well drained. By contrast, hydric soils are poorly or very
poorly drained. A soil's natural drainage rate can be significantly increased by subsurface "tile" drainage.
III. SOIL SURVEY MAPS
A. Soil Series -- A level of Soil Taxonomy, the soil classification system
used in making soil surveys. One example is the "Mardin Series".
IV. SOIL SURVEY INTERPRETATIONS
Become familiar with the interpretive tables within a relatively modern soil survey (since about 1970). These commonly
include soil suitability for uses such as:
A. Agriculture
V. EROSION AND SEDIMENTATION
These are separate processes, but think of them as occurring together, since once soil is eroded it will eventually
become sediment somewhere.
A. Erosion is the "wearing away" of land by the action of water,
wind or ice. It is a natural, geologic process, but often is greatly accelerated by man's activities.
VI. HYDRIC SOILS
A. Introduction
Most of the soils in the U.S. are aerobic. This is important to our food, fiber and forest production because plant
roots respire (that is, they consume oxygen and carbohydrates while releasing CO2) and there must be sufficient
air -- especially oxygen -- in the soil to support root life. As mentioned in the textbook (Soil Science Simplified),
air normally moves through interconnected pores by forces such as changes in atmospheric pressure, turbulent wind,
the flushing action of rainwater, and by simple diffusion.
In addition to plant roots, most forms of soil microorganisms need oxygen to survive. This is true of the more
well-known soil animals as well, such as ants, earthworms and moles. But soils can often become saturated with
water due to rainfall and flooding. Air travels very slowly (some 10,000 times slower) when soil becomes saturated
with water because there are no open passageways for air to travel. When oxygen levels become limited, intense
competition arises between soil life forms for the remaining oxygen. When this anaerobic (no oxygen) environment
continues for long periods during the growing season (April to October in most of NY), quite different biological
and chemical reactions begin to dominate, compared with aerobic soils. In soils where saturation with water is
prolonged and is repeated for many years, unique soil properties usually develop that can be recognized in the
field. Soils with these unique properties are called Hydric Soils, and although they may occupy a relatively small
portion of the landscape, they maintain important functions in the environment.
B. Why are hydric soils important?
The environmental conditions that create hydric soils (water remaining at or near the soil surface for extended
time periods during the growing season) also favor the formation of many types of wetlands.
Wetlands play important roles in the environment, some of which we have only begun to understand and appreciate.
Groundwater is recharged or restored by entering some wetlands; however, in New York soils it is probably just
as common that groundwater discharges (exits) to become surface water through wetlands. During periods of heavy
rains or melting snow, flooding can present a real danger to people and property; but because wetlands occupy depressions
in the landscape they can trap and thereby detain flood waters, thus reducing downstream damages. Wetlands are
often difficult places for humans to physically move around in, so most people avoid them; this is one reason that
they provide critical habitat for many rare and endangered species of flora and fauna. Because wetlands often occur
in relatively low elevations, they commonly receive polluted waters from man's activities on higher, drier ground;
wetlands can effectively filter these waters and retain excess nutrients. Wetlands are also valuable for recreation,
including nature appreciation, hunting, fishing, canoeing, etc.
Due to historical and present development pressures, the number and extent
of wetlands have been greatly diminished (by about 50%!) in the United States since the time when the first white
settlers arrived. Within the last 10 to 20 years, political debates and new regulations have focused on methods
to conserve and rehabilitate wetlands. Because they are formed in association with wetlands, hydric soils can be
used to identify the presence and boundaries of wetlands. In fact, hydric soils were defined so that they help
identify wetlands. Along with unique vegetation and hydrology, hydric soils are one of the three required indicators
for wetland identification. As a result, hydric soils are a very important issue in land management and land planning
across the United States due to their role in the identification of wetlands and their function in wetland ecology.
C. Defining hydric soils
Various government agencies are involved with wetland protection. The NY State Department of Environmental Conservation
(DEC) protects wetlands over 5 hectares (12.4 acres) in size. The US Department of Agriculture - Natural Resources
Conservation Service identifies and protects wetlands that have been used for agriculture. The US Army Corps of
Engineers protects wetlands of practically any size. With the help of soil scientists, they have defined hydric
soils, which they consider to be those soils which are developed under sufficiently wet conditions to support the
growth and regeneration of hydrophytic vegetation:
A hydric soil is a soil that is saturated, flooded, or ponded long enough during the growing season to develop
anaerobic conditions in the upper part.
This definition can be broken up into three component parts:
1) The soil is saturated, flooded or ponded. Saturated conditions are often the result of a high water table. Flooded
conditions are produced by overflowing streams, runoff from higher surrounding slopes or from high tides that inundate
coastal wetlands. Ponded conditions are produced by higher water inflow then water outflow from a closed depression.
2) Wet conditions occur during the growing season. This is the period
of time when the soil is above 5oC or approximately 40oF. Above this temperature, biological activity is significant
and many plants are able to grow.
3) The soil is wet long enough to develop anaerobic conditions in the
upper part. The vast majority of soil biological activity occurs at or near the soil surface. When the soil is
biologically active, a few weeks of wet conditions is usually adequate to use up available oxygen; however, this
can be affected by many factors (e.g. soil and water temperature, the oxygen content of the water, soil organic
matter content, soil permeability, etc.). The important thing is that anaerobic conditions result often or long
enough to support mostly hydrophytic (water-loving) plants. Further, much of the biological activity in soils is
engaged in the decomposition of organic matter either deposited within or on the soil surface. When oxygen is not
available to the soil flora and fauna, biological activity is greatly reduced. As a result, organic material builds
up in the soil. Additionally as a result of the wet, anaerobic environment the soil takes on a characteristic reducing
condition and undergoes chemical reactions that are different than non-hydric soils.
D. Hydric soil properties and indicators
The physical, chemical and biological properties which make hydric soils recognizable are the result of complex
bio-geochemical processes occurring over many years.
Hydric soils usually have a water table, or the top of a zone of saturation, within one foot from the soil surface
during the growing season. This shallow water table excludes oxygen and so creates a reducing environment, especially
in the upper part of the soil profile. As a result, mostly hydrophytic plants proliferate -- such as rushes, cattails,
sedges and skunk cabbage.
Most soils, including hydric soils, are dominantly composed of minerals such as quartz, feldspars, clay minerals,
etc. However, hydric soils commonly have a build-up of organic matter at the soil surface, for reasons described
above, which can make the surface horizon dark colored. If the organic matter content (measured as organic carbon)
is greater than 20 to 30% of the soil's weight (depending upon clay content) and this organic-rich layer is over
16 inches thick, then it is considered an organic soil. Most soil organic matter originates as plant tissue, so
organic soils are called Histosols (the Greek word for tissue is histose). Many types of organic soils exist, but
they can be classified by their thickness and degree of decomposition (see Chapter 12 of text). Peat, such as common
"peat moss", is mostly composed of recognizable plant fragments that are only partly decomposed. Muck
contains highly decomposed organic matter and, when drained of excess water and carefully managed, these black
and spongy soils comprise some of the most important vegetable-producing soils in the eastern US.
Another property unique to hydric soils is their color or color patterns. Besides the dark shading from the presence
of organic matter, iron compounds are the most important coloring agents in soils. Hydric soils tend to exhibit
gray or blue-gray colors (known as gleying or gleyed colors) especially just beneath the topsoil or surface horizon
(see lower portion of photograph). This results from the chemically reduced oxidation state of iron compounds,
as opposed to the rusty red (oxidized) and brown colors of drier, non-hydric soils. Where shallow water tables
fluctuate, gray, yellow and red colors can also occur as small splotches, threadlike or network patterns, created
by accumulations or depletions of iron and manganese (orange colors in photograph). Because they result from processes
of reduction and oxidation these color indicators of wetness are collectively termed redoximorphic features.
Hydric Soils section written by Larry Day (Delaware County Soil and Water Conservation District) and Jonathan Russell-Anelli
(c/o Dept. Soils, Crops and Atmospheric Sciences, Cornell University).
back to the top
Study Outline
I. Soil: What is it?
A. Definition
B. Development
1) parent material
2) processes of development
II. Characteristics
A. Composition
B. Texture
C. Structure
D. Slope
E. Color
F. Chemistry
G. Horizons/Profile
H. Permeability/Percolation
I. Soil Water and Drainage
III. Soil Maps (Know how to use this information)
A. Soil Series
B. Map Symbols
C. Slope Classes
D. Soil Surveys
1) what are they
2) how to use them
IV. Soil Interpretations (Know how to use this information)
A. Agriculture
B. Forestry
D. USDA Land Use Classification
1) prime soils
V. Erosion & Sedimentation
A. Definitions
B. Types of erosion
C. Economic impacts
D. Prevention
1) principles
2) agricultural conservation practices
3) nonagricultural conservation practices
VI. Hydric Soils
A. Definition
B. Characteristics
C. Uses/Limitations
D. Economic Value
Sample Test Questions
Soils Terminology and General Soils Knowledge:
A soil developed in "glacial outwash" refers to its:
a) Moisture condition
b) Temperature classification
c) Parent material
d) None of the above
What size might a single sand particle be?
a) 3 millimeters
b) 3 centimeters
c) .03 millimeters
Which of the following sentences makes the most sense?
a) The consistence of the soil is friable.
b) The consistence of the soil is subangular blocky.
c) The consistence of the soil is silt loam.
Use of Soil Survey Reports:
On the soil map provided, what direction is point A in relation to point B?
a) Point A is Southeast of point B
b) Point A is Southwest of point B
c) Point A is Northwest of point B
d) Point A is Northeast of point B
What soil map unit occurs at the intersection of NYS Rte. 28 and County Rte. 12?
a) MrB - Mardin silt loam, 3 to 8 percent slopes
b) WeB - Wellsboro channery loam, 3 to 8 percent slopes
c) MwB - Mardin and Wellsboro soils, gently sloping
d) MoB - Morris silt loam, 2 to 8 percent slopes
In the tables within the soil survey report, what is the suitability rating of map unit MwB for camp areas?
a) Severe: slope
b) Moderate: small stones
c) Slight
Field Exercises:
Consulting the three soil samples provided (labeled 1, 2 or 3), which soil has a texture of sandy loam?
a) Soil 1
b) Soil 2
c) Soil 3
Using either the clinometer provided or a visual estimate, determine the slope of the soil surface between the
two marked stakes. The stakes are 50 feet apart. Choose the slope range that includes your determination.
a) 0 to 3 percent
b) 4 to 8 percent
c) 9 to 15 percent
d) 16 to 25 percent
e) 26 to 35 percent
In the soil pit, what type of structure exists within the horizon marked by the large nail?
a) Blocky
b) Prismatic
c) Platey
d) Granular
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References
Copies of the books listed below are available for
borrowing from your Soil & Water Conservation
District office. To make arrangements call Nassau at 516-364-5860 or Suffolk at 631-727-2315 x3
Note: These suggested references are listed in decreasing order of relevance
to the Envirothon. Other references may be found to be more useful but are either not generally available, are
written for a more advanced audience, or are unknown to those of us who create questions for Envirothon soils exams.
Soil Science Simplified,
3rd edition, by Milo Harpstead, T. Sauer and W. Bennett. 1997. Iowa State University Press, Ames. Available on
www.amazon.com new $52.99 and used $37.24.
This textbook gives a good introduction to most of the principal topics in soil science. It is profusely illustrated
with simple diagrams, and written for an audience at the high school level. Despite the title, this is a worthwhile
reference book for professionals too, especially when faced with introducing complex soils topics to lay audiences.
The authors use basic concepts from geography, biology, ecology, geology, chemistry and physics to create a comprehensive,
modern perspective of soil science. Chapters include: The Soil Around Us; Formation of Soil; Physical Properties
of Soil; Life in the Soil; Clay and Humus; Chemical Reactions; Soil Water; Heat Flow and Soil Temperature; Soil
Fertility and Plant Nutrition; Soil Management; Soil Erosion; Soil Classification; Soil Surveys; and Engineering
Uses of Soil (plus a glossary and an index). One weakness is the authors' very brief treatment of wetlands and
hydric soils.
Soil Survey of (your county), New York. Available through your county's Soil and Water Conservation District. In Suffolk call
631-727-2315 x3 and in Nassau call 516-364-5860.
Soil survey reports have been available for decades in parts of New York State. The primary purpose of these reports
has always been to provide maps of soils as they occur in the landscapes of each county, and text which describes
important characteristics and uses of each soil type. Newer versions of soil survey reports, those published since
1975, provide considerably more interpretive information than older reports. Being familiar with the content and
format of modern soil survey reports will always be considered an important part of Envirothon soils tests.
Typical tasks that students should know how to do with this reference include: read the general soils map and map
units; locate a given site on the soil map index and detailed soil map; determine distances and directions on soil
maps using the given scale and north arrow; determine soil map units from the soil symbol legend; locate and read
soil map unit or soil series descriptions; locate and use interpretive tables; find and read terms listed in the
glossary section.
FOR FURTHER READING
How to Use a Clinometer.
The Nature and Properties of Soils.
Brady and Weil. Prentice Hall. Available on www.amazon.com
new $130.60 and used $56.08.
A valuable reference for teachers or students devoted to agriculture or environmental science, it provides in-depth
explanations of soil science concepts, along with many diagrams, graphs and photographs.
The Pedosphere and its Dynamics.
N. Juma. 1999. Published by Salman Productions (Order text online for $62.08).
This is both a soils textbook and a free online version of the same text, available at www.pedosphere.com/textbook.html. The online version is a very good resource written by Dr. Juma of the University of Alberta,
Canada.
Note that references to soil classification tend to emphasize the Canadian system, and not the U.S. system of soil
taxonomy.
The following references give good, expanded lessons within each soil subject. They are available through: Curriculum
Instructional Materials Service
Judging Land & Soil for Urban Use.
$10.99
From The Surface Down,
An Introduction to Soil Surveys for Agronomic Use. 1991. USDA
- Soil Conservation Service Staff. 26 pages. pdf format FREE online!
An artfully prepared bulletin which gives a good introduction to soils for agricultural uses as described in most
soil survey reports. It contains high quality color diagrams, photographs of soil profiles and brief discussions
of soil survey terminology.
Soils Biology Primer Order for
$16.00
An introduction to the living component of soil and how it contributes to agricultural productivity, and air and
water quality. There is a discussion of the soil food web and how it relates to soil health.
Sustaining Our Soils and Society; American Geological Institute
Environmental Awareness Series #2; American Geological Institute
in cooperation with USDA-NRCS, and Soil Science Society of America; 1999. ISBN #0-922152-52-0. Available on www.amazon.com new $9.95 and
used $6.15.
An introduction to soil health, sources of soil contamination, and management practices to conserve soils and keep
them productive.
WEBSITES
Soil and Water Conservation Society
National Science & Technology LEFT - Soil Biological Communities
Soil Science Education Home
Page
Urban Soils Primer
Web Soil Survey (allows online viewing of soil survey maps and reports. This new application
greatly enhances access to information on soils.)
Soil Data Mart (determine if spatial and/or tabular data of soil survey is available for specific
county for viewing in ArcGIS)
Helping People Understand Soils - USDA
NRCS
USDA
Natural Resources Conservation Service - Soil Facts
Additional References
Land Judging
and Soil Evaluation. Virginia Polytechnic Institute and State
University.
Field Indicators
of Hydric Soils in the United States. USDA - NRCS.
From the
Surface Down - An Introduction to Soil Surveys for Agronomic Use.
USDA - NRCS.
Hydric Soils. USDA - NRCS.
Master
Horizons and Layers. USDA - NRCS.
Urban Soil Primer. USDA - NRCS.
Building Soils
for Better Crops. Sustainable Agrilculture Network.
Understanding
Soil Risks and Hazards. USDA - NRCS.
Soils Texture
Triangle. USDA - NRCS.
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2009 L.I. Envirothon Soils Station
Old Bethpage Village Restoration in Nassau County
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2009 L.I. Envirothon Soils Station
Old Bethpage Village Restoration in Nassau County
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2009 L.I. Envirothon Soils Station
Old Bethpage Village Restoration in Nassau County
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2009 L.I. Envirothon Soils Station
Old Bethpage Village Restoration in Nassau County
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2009 L.I. Envirothon Soils Station
Old Bethpage Village Restoration in Nassau County
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2009 L.I. Envirothon Soils Station
Old Bethpage Village Restoration in Nassau County
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2009 L.I. Envirothon Soils Station
Old Bethpage Village Restoration in Nassau County
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2009 L.I. Envirothon Soils Station
Old Bethpage Village Restoration in Nassau County
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2009 L.I. Envirothon Soils Station
Old Bethpage Village Restoration in Nassau County
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2008 L.I. Envirothon at the Usdan
Center for Performing and Creative Arts
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2008 L.I. Envirothon at the Usdan
Center for Performing and Creative Arts
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2008 L.I. Envirothon at the Usdan
Center for Performing and Creative Arts
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2007 L.I. Envirothon
St. John's University, Oakdale Campus
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2007 L.I. Envirothon
St John's University, Oakdale Campus
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2005 L.I. Envirothon
St John's University, Oakdale Campus
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2005 L.I. Envirothon
St. John's University, Oakdale Campus
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2005 L.I. Envirothon
St. John's University, Oakdale Campus
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2005 L.I. Envirothon
St. John's University, Oakdale Campus
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2005 L.I. Envirothon
St. John's University, Oakdale Campus
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2004 L.I. Envirothon
St. John's University, Oakdale Campus
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2004 L.I. Envirothon
St. John's University, Oakdale Campus
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2003 L.I. Envirothon
Belmont State Park
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2003 L.I. Envirothon
Belmont State Park
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2003 L.I. Envirothon
Belmont State Park
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2003 L.I. Envirothon
Belmont State Park
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2003 L.I. Envirothon
Belmont State Park
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2003 L.I. Envirothon
Belmont State Park
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2002 L.I. Envirothon
Belmont State Park
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