BASIC SOILS TRAINING PROGRAM MANUAL

is nearly parallel to the soil surface. Some soil horizons are easy to distinguish from another horizon that lies above or below because there is a distinct boundary between the two layers. Other horizons change so gradually with depth that it is difficult to determine their boundaries. 2 COMPONENTS OF SOIL There are four basic components of soil. These are minerals, organic matter, water, and gases. Soil Minerals: Particle Size Mineral Type vs. Size. Mineral material is the most abundant component of most soils. Two important ways to classify minerals are by the SIZE of the mineral particle and by the TYPE of the mineral particle. The most common type of mineral in Florida soils is quartz. For the purpose of making most Onsite Sewage Treatment and Disposal System (OSTDS) land use decisions, particle SIZE is the mineral classification scheme that is most important to consider. Three Mineral Sizes. The three basic sizes of soil mineral particles are SAND size, SILT size, and CLAY size. Each basic particle size has distinguishing properties that can be observed even when the individual particles cannot be seen. Sand. Soil minerals are essentially weathered rock. The forces of nature, over time, have split and crushed rocks until they have become the size of a SAND grain. SAND is the largest soil particle. Sand ranges in size from 0.05 millimeters to 2.0 millimeters in diameter. Individual sand particles can be seen by the naked eye. Sand feels gritty when rubbed, and barely holds together when moist. Water moves through sand rapidly to very rapidly. Sand is nearly inert (it has very low chemical activity). It supplies few or no nutrients to plants. Sand Size Subdivisions. The sand particle can be subdivided into more detailed classes. These are very coarse sand, coarse sand, medium sand, fine sand, and very fine sand. Very coarse sand particles are about the size of a lower case alphabetic character produced by a standard typewriter. Medium sand particles are about the size of a sugar grain. Fine sand particles are about the size of pin point or the diameter of a strand of hair. Individual particles of very fine sand are difficult to see without the aid of a magnifying glass. Fine sand and Medium sand (medium sand is referred to simply as "sand") are the most common of the sand sizes that are found in Florida soils. Coarser sands are not common in Florida soils but are sometimes found on banks of swift flowing rivers and on beaches. Silt. The SILT sized particle is intermediate in diameter between sand and clay. If you were able to smash a sand grain with a hammer until it became powdery, you would have created silt particles. The diameter of an individual silt particle is 0.002 to 0.05 millimeters. Individual particles of silt are difficult to see without magnification. When moist, silt feels smooth and silky. It holds together well when molded, but cannot be formed into a RIBBON. (A ribbon is a thin, flat, elongated form that can be molded from materials containing clay). Silt is somewhat chemically active. In Florida, soils dominated by silt are not common. They are primarily found on the floodplains of large rivers, in some tidal marshes, and in broad areas of the southernmost part of the Florida Peninsula. Clay. The smallest soil mineral particle is the CLAY sized particle. Individual particles of clay have diameters that are smaller than 0.002 millimeters. Individual particles of clay are so small that they can only be viewed using powerful microscopes. Clay is chemically active, and may provide a large amount of nutrients to plants. Water moves slowly through materials dominated by clay particles. Clay is easily molded into shapes, or into a long ribbon that will hold together without easily breaking. It may be sticky when moist. It is rare to find soil materials that are pure silt or pure clay (nearly pure sand is common). Most soil materials are a mixture of the three particle sizes. For example, a soil layer might contain material that is 75 percent sand, 10 percent silt, and 15 percent clay. We refer to this mixture of particle sizes as SOIL TEXTURE. 3 PARTICLE SIZE CLASSIFICATION FOR SOIL MINERALS Size (diameter) Class Identification <0.002 mm clay need powerful microscope to see 0.002 mm to 0.05mm silt regular microscope needed 0.05 to 2.0 mm sand visible to naked eye Figure 1. Soil Minerals: Texture Field vs. Laboratory Determination. Soil texture can be accurately determined in the laboratory using various measuring techniques or soil texture can be estimated in the field by rubbing a MOIST sample between the fingers. It is generally impractical, time consuming, and costly to send permit site samples to the laboratory; however with practice, the field estimate can be quite accurate, and acceptable for the planning of onsite sewage treatment and disposal systems. Texture and Soil Properties. Because each different size of mineral particle has unique properties, soil material that is a mixture of sand, silt, and clay will have properties that are influenced by each of the different particle sizes. For example, soil material that is 40 percent sand, 40 percent silt, and 20 percent clay will have some grittiness, like sand; some stickiness, like clay, and be able to hold a substantial amount of water, like silt. The Textural Triangle. In order to simplify the description of particle size mixtures, a system was developed called the USDA SOIL TEXTURAL CLASSIFICATION. In this scheme, twelve classes of soil texture are depicted on a 3-axis graph called the USDA SOIL TEXTURAL TRIANGLE. USDA Textural Classes. A LOAM is a mixed textural class that has properties nearly equally derived from each of the three particle sizes. Loam is somewhat gritty, a bit sticky, yet also smooth when rubbed. It contains 7 to 27 percent clay, 28 to 50 percent silt, and less than 52 percent sand. Note that the Loam class is located at the lower center of the textural triangle. Other textural classes are positioned to the left, right, or above the loam class on the textural triangle. Classes to the left of loam contain a higher percentage of sand particles; classes to the right contain a higher percentage of silt particles and classes above contain a higher percentage of clay particles. For soil materials that are dominantly sand, dominantly silt, or dominantly clay, there are soil textural classes by the same name of the dominant particle: the SAND class, the SILT class, and the CLAY class. The SAND textural class contains mostly sand particles, but may contain some silt particles and clay particles. Similarly, the SILT textural class, contains mostly silt particles, and the CLAY textural class contains mostly clay particles. Other soil textural classes include SILT LOAM, CLAY LOAM, and SANDY LOAM; LOAMY SAND, SANDY CLAY, and SILTY CLAY; SANDY CLAY LOAM and SILTY CLAY LOAM. Common Soil Textures in Florida. The most common soil textures in Florida are fine sand, sand, loamy fine sand, loamy sand, fine sandy loam, sandy loam, sandy clay loam, and sandy clay. On occasion, the textures clay, clay loam, and loam are encountered. In most parts of the state, it is extremely rare to find soil materials with textures silt loam, silty clay loam, silty clay, and silt. Note that the most commonly occurring textures in Florida are those depicted on the lower left corner of the USDA TEXTURAL TRIANGLE. Textural Class Names Modified by Sand Sizes. Only the textural classes sand, loamy sand, and sandy loam are modified by the sand size subdivisions. Examples of the modified classes are fine sand, loamy very fine sand, loamy coarse sand, and very fine sandy loam. Detailed written descriptions of these and the other textural classes are found in the section on USDA Soil Textural Classification System in Chapter 64E-6. Broad Textural Categories. Three broad categories are sometimes used when referring to the dominant texture of a soil. These are not true categories of the USDA SOIL TEXTURAL CLASSIFICATION SYSTEM, but rather unofficial groups often used in conversation by soil scientists. SANDY soils have textures that are primarily sand (including the subdivisions of fine sand, etc.). SAND is the dominant constituent. For example, all sands (coarse, medium, fine and very fine) and all types of loamy sands, EXCEPT FOR LOAMY VERY FINE SAND, WHICH IS CONSIDERED A LOAMY SOIL. LOAMY soils are those having a texture of one of the classes with 4 loam or loamy in the class name where loam is the dominant constituent. For example sandy loam, fine sandy loam, clay loam or sandy clay loam. CLAYEY soils have textures in the classes of sandy clay, silty clay, or clay. NOTICE THAT THE DOMINANT PARTICLE SIZE IS NAMED LAST IN ALL INSTANCES, EXCEPT AS NOTED. Touch Texturing. When estimating the soil textural class by the field method called TOUCH TEXTURING. The sample must have enough water in it so that the finer textured soil aggregates (silt and clay particles) have been completely broken down and it is like moist putty in your hand. Do not use soil that is too wet or too dry. Sandy soil textures will not feel like moist putty. Use the textural flow chart guide provided in this manual until you have it committed to memory. Proficiency in touch texturing is possible only with experience and practice. The flow chart should be used to determine textural groups in conjunction with the textural triangle. Soil samples with known laboratory determined particle size distribution can be valuable learning tools for reference. Coarse Fragments. Mineral particles that have a diameter greater than 2.0 millimeters are called COARSE FRAGMENTS. Coarse fragments include gravels, boulders, and stones. While coarse fragments are not counted towards the percentage of soil mineral particles in the textural classification, they can be used as a modifier. For example, a sample of soil having a texture of sandy loam and containing an additional 15 percent of gravels (by volume, not weight), is called a GRAVELLY sandy loam. If the sample contains a minimum of 35 percent gravels, the modified textural classification would be VERY GRAVELLY sandy loam. Continuous bedrock that lies below a soil layer is not considered to be part of the soil, nor is it considered to be a coarse fragment. Soil scientists classify it by type of rock, (usually limestone in Florida) and by its degree of hardness (hard versus soft). Soft bedrock can be excavated by light power equipment and hard bedrock cannot be excavated by light power equipment. Organic Matter ORGANIC MATTER is the second solid component of soils. Organic matter consists primarily of pieces and parts of plants that are in various states of decay. Organic matter is also sometimes called humus. Generally, less decayed materials lie on the soil surface, especially where there is a thick canopy of trees. Effects of Organic Matter on Mineral Soils. The soil layer often called topsoil, is a mineral layer that is dark colored because it contains a small amount of well decayed organic matter, generally less than 2 percent. Organic matter is normally black or brownish colored and so it imparts a black or brownish color to the soil. Organic matter also increases the water holding capacity of the soil. Usually, a small amount of organic matter adds tilth, or loosens the soil, making it less compacted (dense). Compare that to the scenario where a soil material contains a substantial amount of organic matter, any weight placed on the soil can increase the compaction. Both can be compacted, but the higher the organic matter content, the more it can compact. Organic Matter in Dry vs. Wet Soils. In very dry to dry sandy soils, very little organic matter accumulates and there may be none to very little black or brownish coloration to the topsoil. In contrast, wet soils usually have dark colored layers containing large amounts of organic matter. Some wet soils, especially those in swamps and marshes, have thick layers consisting of all or nearly all organic matter with little or no mineral soil material. This is called ORGANIC SOIL MATERIAL. Kinds of Organic Soil Material. MUCK and PEAT are terms used to describe organic soil materials comprised of about 20 to 30 percent (or more) organic matter. Muck is used to describe a greater state of decay than peat. Most organic soil materials in Florida are classified as muck. Remember that texture refers to mineral soil materials only, but if the soil material is muck, it is used in place of texture. If a soil material contains about 10 to 20 percent organic matter, the terms MUCKY or PEATY are used as textural modifiers. For example, a mineral soil material with the texture fine sand, and containing about 15 percent organic matter would be called MUCKY FINE SAND. In general, if the muck or peat layers in a soil are greater than 16 inches thick, the soil is called an ORGANIC SOIL. Water: The Mobile Soil Component All soils contain spaces between individual particles and between soil aggregates (clumps of particles). Most soils contain about 50 percent pore space and these pores are filled with either air or water. Air and water are the last two non-living components of soil. It is the movement of water through the soil that is extremely important for OSTDS design. Permeability. Water moves through the soil at variable rates depending on the physical properties of the soil. Many different terms are used to describe water 5 movement through soils, each having a slightly different definition. For our purposes the rate or speed at which water moves through a soil, a soil horizon, or through material used for fill, will be referred to as PERMEABILITY. In general, sandy soils have the highest permeability rates and clayey soils have the lowest permeability rates. There are some exceptions to this generality. For example, a common sandy soil found in Florida has a layer below the surface that has a slower permeability than might be expected for a sandy layer. This layer is called a SPODIC horizon, or stained layer. The significance of the spodic horizon will be discussed at a later point. USDA Permeability Classes. Classes for the standard USDA soil permeability rates are given in the following table. These classes define estimated values. They are obtained by considering laboratory measured rates of saturated soil samples along with such factors as volume of coarse fragments, degree of soil compaction, and soil texture. The USDA permeability classes are used to describe either the rate of water movement through a specified horizon (horizon or layer permeability), through soil material or geologic material, or the rate of water movement through the entire soil (soil permeability). If applied to the entire soil, the permeability used is that of the most restrictive (slowest) permeability of any horizon in that soil. Note that the permeability rates are for undisturbed native soils. Also, permeability rates are for the movement of water through the soil, not effluent from a septic tank. Permeability vs. Water Tables. Although permeability has a profound effect on the kind of water table and the depth to the water table, permeability and wet season water table should never be confused. Do not assume for example, that because a sandy soil has a rapid permeability, that it must be a well-drained soil. If the water has no outlet, then the soil pores will remain saturated with water, and despite rapid permeability, the soil will be poorly drained. Permeability vs. Loading Rates. Do not confuse the permeability rates given here with the loading rates given in Chapter 64E-6, Florida Administrative Code. Although the terms are similar, the units of measurement are different, as are the boundaries of the classes that describe loading rates. Altered Soil Permeability. The discussion has focused thus far on the correlation between soil texture and permeability. This relationship is strong. However it should be emphasized that other factors affect permeability and should be considered when estimating the permeability rate. Compaction of the soil by vehicle traffic (especially construction traffic) can significantly reduce permeability. The aggregation of loamy or clayey soils into SOIL STRUCTURES, called peds, can greatly increase permeability in loamy and clayey soils. Medium size and large size roots of shrubs and trees can be conduits for water and thus increase permeability tremendously. There are many other factors affecting permeability that are beyond the scope of this manual. Any good estimate of a permeability rate should consider obvious site factors and data presented in the published or web soil survey. Note that any weight placed on the soil can increase the compaction and hence decrease permeability. USDA Permeability Classes Permeability Class Rate (inches per hour) very extremely slow 0.0 to 0.01 extremely slow 0.01 to 0.06 very slow < 0.06 slow 0.06 to 0.2 moderately slow 0.2 to 0.6 moderate 0.6 to 2.0 moderately rapid 2.0 to 6.0 rapid 6.0 to 20.0 very rapid > 20 Gases. The fourth component is gas. The pores in the soil that are not filled with liquid will have some type of gas in them. 6 DESCRIBING SOILS USDA notation and terminology for describing soils is the most widely used methodology today and thus should always be used to attain the maximum transfer of technology. Regarding the OSTDS program, the use of USDA techniques, notation and terminology are required. No other methodology can be accepted. Munsell Color Notation Hue, Value, and Chroma. Munsell color notation is used to describe soils so that there is accurate communication about soil color. The Munsell color system utilizes three descriptive elements called HUE, VALUE, and CHROMA. In the reddish Munsell color ‘10R 4/6’, 10R is the hue, 4 is the value, and 6 is the chroma. The descriptive elements of this system are organized into a book of colors (Munsell Color Book) much like a paint store uses color strips. The Munsell Color Book must have all of the current hue cards in order to be used (and be clean and have all chips). Hue. Hue identifies the basis spectral color or wavelength (the relationship to the colors Red, Yellow, Green, Blue and Purple). In soils, these are the hues Red, designated by a capital R and Yellow, designated by a capital Y. Halfway between the Hue R and the Hue Y, is the hue YR, which represents yellow-red. Each hue consists of a different page in the Munsell color book. All of the colors on a single page have the same hue, except for the gley charts. In Florida, the basic hues are supplemented by several intermediate hues. The hues in progression from red to yellow are 5R, 7.5R, 10R, 2.5YR, 5YR, 7.5YR, 10YR, 2.5Y and 5Y. The Gley Charts. There are two supplemental charts called the GLEY charts. These group many of the grayish, bluish, and greenish colors often found in very wet mineral soils. The gley chart contains several hues on one page, and they contain more yellow than the other non-gley charts. Chart One has the hues N (these hues have value, but no chroma designation), 10Y (yellow), 5GY (green-yellow), 10GY and 5G (green). Chart Two has 10G, 5BG (blue-green), 10BG, 5B (blue), 10B and 5PB (purple-blue). In older versions of the Munsell Color Book, colors with chroma of 0 appear on some of the single hue pages. Soils with colors on the gley charts are very wet. Munsell books that do not have a complete, clean set of gley charts must be updated. Value. Value indicates the degree of lightness or darkness. Note on the first column of any page (any hue) that value increases from black at the bottom of the page, through the grays, to nearly white at the top of the page. Pure white would have a value of 10 in the Munsell scale and pure black would have a value of 0. Chroma. Chroma is the relative strength or purity of the color. As chroma increases, the color becomes more intense. The scales of chroma extend from 0, which indicates no strength, or the lack of spectral color, to 20 which has the greatest amount of spectral color (for soil color, chroma ranges from 0 to 8). When chroma equals 0, the HUE is classified as neutral and therefore specified as "N" in the notation. That means for example that the color 2.5YR 3/0 is exactly the same color as 7.5YR 3/0. When chroma equals 0, the notation used is N chroma/value, as in the expression N 3/0. The expression may also be simplified to N3. These colors have no hue and no chroma, but range in value from black (N2.5) to white (N8). An example of a notation for a neutral (achromatic) color is N5 (gray). A column of color chips with neutral hue and no chroma is located on chart one for gley colors. Field Measurement of Soil Color. When measuring soil color the sun should be behind you. The evaluator should not be wearing sunglasses or any type of tinted lenses. Very early morning or late afternoon measurements are not accurate. The sample should be moist. A moist sample will not get any darker when water is added to the sample, and it will not glisten. A sample that is too wet will glisten in the sunlight, or the water puddles on the sample. The sample should be placed behind the holes on the unaltered color chart so that the sun shines on the chip and soil sample (no shadows) and compared to the color chip that is most like the color of the soil sample. It is understood that an exact match is not likely, but that the closest color match will be used. In Florida, it is usually best to start on the 10YR page and make page turns to the left if the hue is not red enough, or make page turns to the right if the hue is not yellow enough. When the closest match is found, write the color notation using the hue (page) first, followed by value (left column), then write a slash, followed by the chroma (look to the bottom of the page); for example, "10YR 4/4". Care must be exercised to keep the color chips clean. These pages MUST be used in an unaltered form, meaning that they cannot be copied, laminated, etc. 7 USDA Horizon Designations Soil Profiles. The best way to study a soil is to dig a fresh pit in the ground and examine the wall or face of the pit. The face of the pit shows a sequence of horizons called the SOIL PROFILE. We describe each horizon in the profile by first designating a symbol, for the type of layer, followed by the depth in inches where the horizon begins and ends (for example, 0 to 9 inches), followed by the Munsell name of the color, the Munsell notation in parentheses, and the soil texture. For example, consider the following description: USDA NOTATION A1--0 to 9 inches; (10YR 2/1) fine sand; Bt1--9 to 15 inches; (10YR 5/6) and (7.5YR 5/4) SCL If there are mottles (be they redoximorphic features or not), they are described next by color and abundance. Mottles are described in quantity, contrast and color. Redoximorphic Features are mottles that indicate seasonal high water table elevations. Quantity is indicated by three percentage classes of the observed surface. These are: Few (<2%) Common (2 to 20%) Abbreviation is CMN. Many (>20%). No abbreviation. Write out. Size refers to the dimensions as seen on the plane surface. If the length of the mottle is not more than two or three times the width, the dimension recorded is the greater of the two. If the mottle is long and narrow, as a band of color at the periphery of a ped, the dimension recorded is the smaller of the two and the shape and location are also described. Three classes are used. Fine: <5mm Medium: 5 to 15mm Coarse: >15mm Contrast refers to the degree of visual distinction that is evident between associated colors. The color contrast (faint, distinct, prominent) is determined by use of Soil Survey Technical Note Number 2, Soil Color Contrast, found later in this manual. For example, the soil color contrast between a 10YR 5/4 and 10YR 5/8 is no change in hue or value, but a change of four units of chroma, which would be a prominent color contrast. DO NOT COUNT CHIPS (OR PAGES FOR HUES) TO DETERMINE COLOR CONTRAST, COUNT THE UNITS OF DIFFERENCE BETWEEN HUES, VALUES AND CHROMAS, RESPECTIVELY. Faint mottles are only evident upon close examination. They commonly have the same hue as the color to which they are compared and differ by no more than 1 unit of chroma or 2 units of value. Distinct mottles are those that are readily seen but contrast only moderately with the color to which they are compared. They commonly have the same hue as the color to which they are compared to but differ by up to 3 units of chroma and up to 3 units of value. Distinct is abbreviated as DST. Prominent mottles contrast strongly with the color to which they are compared. Prominent mottles are commonly the most obvious color feature of the section described. Prominent mottles that have medium chroma and value commonly differ from the color to which they are compared by at least 5 units (two pages) of hue if chroma and value are the same; or by at least 4 units of value or chroma if the hue is the same. Prominent is abbreviated as PRM. It can also be stated that bright mottles are those that appear to moderately or substantially contrast with the matrix, or the dominant color of the layer. These could be referred to as distinct or prominent mottles, respectively. These are the minimum parameters needed to sufficiently describe a soil for OSTDS interpretations. For DOH OSTDS site evaluations, the minimum standard is the correct Munsell notation, followed by the soil texture, then the depth in inches where the horizon begins and ends. For example: 7.5YR 4/2 FS 0-6" The redoximorphic features (abbreviated as RF) must be identified in the soil profile on a separate line, or in the remarks section. For example: The following matrix soil color and textures are in a horizon at a depth of 15-28”: 10YR 6/4 FS 15-28”, which would be followed by the redoximorphic features that exist within that horizon. For example: 10YR 6/6 CMN/DST RF FS 17-20" The reason the soil color contrast is distinct is because there is no change in hue or value, but two units of change in chroma. Review of the soil color contrast memo shows this to be a DISTINCT contrast. It is allowable to identify the actual percentage of redoximorphic features, such as: 10YR 6/6 5% DST RF FS 17-20" 8 Additionally, any restrictive layers must be properly identified, for example a spodic horizon (a Bh horizon) could be noted as: 5YR 3/2 FS spodic 20-30" Auger Investigation. Since it is typically impractical to dig a fresh pit for every onsite investigation, the soil is usually examined using a bucket auger. Each sample brought to the surface in the auger must be carefully examined to determine if there is a sufficient difference in texture and/or color to designate a new horizon. Texture and color pattern are the parameters used most to distinguish one horizon from another. Note that the use of a bucket auger less than 2¾ inches provides a comparatively small sample. Consequently, soil indicators could be less abundant and more difficult to identify. The use of a larger bucket will increase the amount of surface area where soil indicators would be present. The best place to observe soil conditions is in the center of the bucket auger sample. Remove the sample from the bucket, keeping it intact and then separate it into two halves on the long axis. This provides a natural, relatively undisturbed sample for color identification and soil texturing. Soil coloring should be done prior to soil texturing. Accurate profile descriptions require many hours of study and good observational skills. Horizon Designation Symbols. The horizon designation symbol is related to the color, texture and other characteristics of the layer with respect to how the layer formed. The symbol usually consists of a capital letter and a lower case subscript, if applicable. O Horizon. A layer of organic matter on the surface of a mineral soil is called the O horizon. This soil layer consists of decaying plant residues. In an extremely wet soil it is comprised of peat (partially decomposed, where individual pieces of plants are identifiable), or muck (where all plant material is totally decomposed). This layer has the master horizon designation of a capital O (for Organic). L Horizon. Limnic (means fresh water) Includes both organic and mineral limnic materials that were either (1) deposited in water by precipitation or the action of aquatic organisms such as algae or diatoms, or (2) derived from underwater and floating plants and subsequently modified by aquatic animals. These layers include coprogenous earth (sedimentary peat), diatomaceous earth, and marl. They occur only in Histosols (organic soils). They have the following subordinate distinctions (suffixes) of co (coprogenous), di (diatomaceous), ma (marl). They do not have the subordinate distinctions of other master horizons. A Horizon. The topsoil layer, colored dark by organic matter, is always designated with a capital letter A. The surface layer is almost always an A horizon. The subscript ‘p’ indicates that the surface has been plowed (Ap). On disturbed sites, the A horizon may be missing due to erosion or removal (e.g. grading). The Classic Soil Profile. A classic soil profile would have a subsurface layer next, followed by subsoil layer, and a parent material layer. However, layers are sometimes missing from the sequence. For example, there is not always a subsoil layer or the parent material layer may be too deep in the profile to describe. E Horizon. The typical subsurface layer is a "LEACHED" zone from which downward moving rainwater has translocated either clay particles and/or iron and other substances. This zone is designated by a capital E. An E horizon is always followed by a subsoil layer. B Horizon. The typical subsoil layer underlies the subsurface layer. In Florida, the typical subsoil contains an accumulation of clay particles or aluminum complexed with organic acids. Most of the substances accumulated in the subsoil were leached from the overlying A horizon and/or the E horizon. The subsoil is designated the B horizon. C and R Horizons. The material below the B horizon, generally lacks evidence of soil development and is usually considered to be relatively unaltered parent material. It designated the C horizon. Hard bedrock is designated the R horizon. The R horizon can also be considered parent material if it is thought that the soil formed in place from the weathering bedrock. M Horizon. Root-limiting subsoil layers consisting of nearly continuous, horizontally oriented, human- manufactured materials. Examples are geotextile liners, asphalt, concrete, rubber and plastic. W Horizon. Water. This symbol indicates water layers within or beneath the soil. The water layer is designated as Wf if it is permanently frozen and W if it is not permanently frozen. The W (or Wf) is not used for shallow water, ice or snow above the soil surface. Transitional Horizons. Sometimes if a layer looks and feels similar to both the layer above and the layer below, a transitional layer is designated by the conjugation of two master horizon symbols. For 9 example, a layer that was intermediate in color between an overlying A horizon and underlying E horizon, may be designated as the AE horizon. Horizon Subscripts. Numerous subscripts can be attached to the master horizons designated by the capital letters. A ‘g’ indicates that the horizon is predominantly a “gley” color or gray color which is normally chroma 2 or less, and includes the colors on the gley charts, with the exceptions noted earlier. The low chroma can be the color of reduced iron or the color of uncoated sand and silt particles from which iron has been removed. These areas may include redox concentrations. A ‘t’ may be used with a B horizon to indicate a subsoil accumulation of clay or an ‘h’ indicates an accumulation of organic acids. The Bh horizon is the spodic horizon referred to earlier. Other subscripts used in Florida soils include ‘w’ and ‘v’ for subsoils. A ‘v’ indicates the accumulation of soft iron nodules (plinthite) and a ‘w’ indicates development of a subsoil layer without the accumulation of substances found in Bt and Bh horizons. A ‘b’ is used to indicate quickly buried soil layers. The layers have usually been buried within the past several hundred years and are recognizable as soil layers as opposed to sedimentary materials. Classification of the Soils. This section in the soil survey manual deals with soil series and their morphology, or their structure and form. Here you will find detailed descriptions of each soil horizon for each soil series that is recognized in the soil survey area. Additional information that you will find here is the type of topography the soil is normally located on and the soil drainage classification. You will note that there is a listing of geographically associated soils. The listing of the associated soils will normally indicate some of the differences among the soils. It is important to note that after the detailed descriptions there is information on variations on thickness, textures and colors of the soil horizons. This information is extremely important in determining soil classifications. When performing a soil profile, it is understood that an exact match is not likely, but that the closest match will be used. You could also encounter variations in a soil profile. Use of the information regarding the variations allowed in describing the soil color will assist in identifying the soil series. Accurate classification of soils require many hours of practice and good observational skills. Soil Taxonomy: How Soils Are Classified Soil Taxonomy is the USDA classification system used by soil scientists to group like soils and give them names. The system is a complex one that is well beyond the scope of the current discussion. For making most OSTDS decisions, it is only necessary to be familiar with the concept of soil classification. Therefore, only a brief overview will be featured here. Soil Taxonomy is a hierarchical system that has several levels of classification, just as the biological classification system that is used to classify plants and animals. Consider for example that humans are first distinguished as animals (vs. plants) then they are in the kingdom of animalia, phylum chordata, class mammalia, order primata, family homidae, genus homo, species sapiens. In a similar way, a soil is first classified as mineral or organic, then into a soil order, a suborder within the order, a great group within the suborder, a sub group within the great group, and a family within the great group. A name is then conjugated from the formative components of the order through the family. For example, the soil series Myakka is a mineral soil classified as a Sandy, siliceous, hyperthermic Aeric Alaquod. Sandy siliceous hyperthermic is the family indicating quartz sand composition in a warm climate; Aeric is the greatgroup indicating a relative thin surface due to slightly more aeration; Al is the subgroup formative element indicating an aluminous subsoil complexed with organic acids; Aqu is the suborder formative element indicating wetness and Od is the soil order formative element for the order of Spodosols. Soil Orders In Florida Soil orders commonly found in Florida are discussed briefly below. Histisols. These are the organic soils (they are almost always very wet soils). The formative suffix for this order is ist, as in the suborder Saprist. Entisols. These are weakly developed soils or ones that are sandy throughout (excluding spodosols). The formative suffix for this order is ent, as in the suborder Aquent. Spodosols. These are sandy soils with a subsoil accumulation of organic acids called a spodic horizon. The spodic horizon is sometimes called an organic hardpan, but this term should be used carefully because not all spodic horizons are hard and dense. Myakka fine sand, the state soil of Florida, is a spodosol. The formative suffix for this order is od, as in the suborder Aquod. Mollisols. These are alkaline or non-acid soils with thick black surfaces. In Florida, they are usually wet 10 soils. The formative suffix for this order is oll, as in the suborder Aquoll. Inceptisols. In Florida, these are essentially soils that do not fit well into the other soil orders. It includes soils similar to Mollisols that are acid instead of alkaline and some floodplain soils. The formative suffix for this order is ept, as in the suborder Aquept. Alfisols and Ultisols. These are soils with loamy or clayey subsoils that underlie horizons with less clay. Alfisols have alkaline subsoils and Ultisols have acid subsoils (more or less). The formative suffixes are alf and ult, as in the suborders Aqualfs and Aquults. Typical Horizon Sequences Each of the Florida soil orders has a typical sequence of horizons. It must be stressed however that numerous variations of the basic sequence are possible. For the sequences given below, those horizon designations (or parts of the designation) delineated in bold, are most diagnostic for the specified soil order. Histosols Oa, Oe, C1, C2. Entisols A, C1, C2, C3. Spodosols A, E, Bh1, Bh2, BC, C. Mollisols Ap, A1, A2, AC, C. Inceptisols Ap, E, Bw, BC, C. Alfisols and Ultisols Ap, E1, E2, Bt1, Bt2, BC. Representative Profile Schematic of the Classic Soil Profile A-Topsoil. Mineral horizon Surface layer colored dark by organic matter. AE-Transitional horizon Subsurface layer. has characteristics similar to both the A & E horizons E – Horizon of maximum leaching, Subsurface layer. or loss of substances such as clay particles Bt or Bh – Horizon of Subsoil layer. maximum soil development, usually the accumulation of organic acids or of clay particles. C-Horizon of geologic material that Substratum or underlying layer is relatively unaltered by soil forming processes. Figure W 11 SOIL WATER TABLES In Florida, the soil water table is the soil property most often considered for planning a variety of land uses. For urban land uses, the problem is likely to be "too much water" rather than "not enough water." Where to Start Measurements All indicators are measured from the natural soil surface, which includes all horizons that were made by the soil forming process. The natural soil surface is measured from mineral, muck or mucky mineral soil. Do not measure from peat or mucky peat surface unless using Hydric Soil Indicators A1, A2 or A3 (note for A3: this one would be an unusual case and probably would never meet the color requirement). Where the natural soil surface has been altered by the action of man via soil addition or removal, the indicators must be judged using natural soil surface criteria, accounting for what was added or removed. As a notation, remember that redox features may form in fill material and extra care must be taken during their evaluation. Water Table Fluctuations. The soil water table is the depth to saturated soil material. The depth to the water table can be measured at any time, but a single measurement is not useful for making land use interpretations. A group of water table measurements, taken weekly over a period of many years, will show how the water table fluctuates up and down in a soil. Unfortunately, this method is not practical for most land uses. Using soil morphology however, it is possible to predict the depth to the SEASONAL HIGH WATER TABLE (SHWT), also sometimes called the wet season water table. SHWT Definition. The SHWT is the highest average depth to a zone of saturation. The SHWT normally persists at its depth for several weeks or more, and normally occurs during the time of the year when the most rain falls. Informationally, the USDA NRCS uses a 30 day criteria to judge SHWT for the ranges presented in their soil surveys. In addition, because some years are drier than others, and some years are wetter, the SHWT may not be reached in some years while it may be exceeded in other years. Many different factors affect the seasonal high water table including climatic variation, relative landscape position, landscape development, vegetation, and soil texture. Although it is soil morphology that is the basis for SHWT estimation, other factors should always be considered. Matrix and Mottle Color as SHWT Indicators Soil Color is the dominant morphological feature used to predict the SHWT. Soil color determination and terminology is obtained from the Munsell soil color charts. When describing the color of a soil horizon, there are two components to be considered. Recall that the dominant color of the layer is called the matrix color and splotches of color are called mottles (where indicative of the seasonal high water table, they are termed Redoximorphic features or RF). Often, mottles are not present in a soil horizon, but when they are present, both the color of the matrix and the color(s), amount and contrast of the mottles must be described. The color contrast (faint, distinct, prominent) is determined by use of Soil Survey Technical Note Number 2, Soil Color Contrast, found later in this manual. DOH and Hydric Soils/Redoximorphic features from Natural Soil Surface to 12 Inches and use of Hydric Soil Indicators (HSI). DOH does not define the term “hydric soil” nor exert regulatory control because the soil may be hydric. In the broadest sense a hydric soil equates to a SHWT within 6” of the soil surface if a sandy soil, or within 12” if non-sandy. Hydric soils have specific indicators that are used to identify them, collectively called Hydric Soil Indicators (HSI). The HSI used in Florida and their descriptions can be found later in this manual. Note that HSI must be used to determine the SHWT in all soils from surface down to 12”. Additionally, HSI can also be used as SHWT indicators at depths greater than 12”, just make sure you follow the specific criteria for the indicators, except for them having to be within 6” or 12” of the surface. Redoximorphic Features in Loamy and Clayey Soils. In loamy or clayey soil horizons, INCLUDING THE TEXTURE LOAMY VERY FINE SAND, the best indicator of the depth to the seasonal high water table below a depth of 12” (30 cm) from the natural soil surface is the depth to grayish low chroma soil colors, either as the matrix or have common appearance as “mottles” (iron depletions). These low chroma colors have a value of ≥5 (note the higher values) with a chroma of ≤2 down to a depth of one meter (39.37 inches). Below one meter, the depth to saturation is the depth to common to many distinct or prominent redox 12 depletions or a matrix color with value ≥5 and chroma ≤3. There is an important exception to use of this color pattern as an indicator. If low chroma colors directly underlie a dark topsoil layer, the SHWT is at, near, or above the soil surface. Additionally, Hydric Soil Indicators can be used to determine the SHWT at any depth in the profile. Note that the Gley Chart colors having a value ≥4 are also indicators. Note: For depths of one meter or less, depletions of chroma 2 or less is required and for depths of more than one meter, depletion of chroma 3 or less is required. The difference is that this phenomenon is reported from thousands of field sites, and by remembering that the requirements for reduction (microbial activity, saturated soil, lack of oxygen and organic matter) become less and this might lead to less dissolution of iron even when the soils are just as wet and just as reduced. Redoximorphic Features in Sandy Soils. In sandy soils or soil horizons, the best SHWT indicators below a depth of 12” from the natural soil surface are the depth to bright colored redox features (concentrations) and/or a gley color matrix. THIS IS FOR THE TEXTURE LOAMY FINE SAND AND COARSER. Recall that gley colors are low chroma colors, including types of greenish, grayish, and bluish low chroma colors found on special charts in the Munsell Color Book called the gley charts and values ≥4 are considered redoximorphic features. Bright mottles are those that appear in substantial contrast to the matrix. These are more accurately described as distinct or prominent mottles, which were discussed in a prior section. See USDA NRCS Technical Note 2, Soil Color Contrast later in this manual for color contrast identification procedures. The matrix has a chroma of ≥3 and/or high value and the mottles are mid value (≥5) and high chroma (≥6). Sometimes the appearance of bright mottles will coincide with an abrupt matrix color change. A likely change is from a brighter matrix color above to a lighter (often white) matrix color below. In sandy soils with a chroma ≥3 and below a depth of 12” from the natural soil surface, the depth to saturation is the depth to common to many distinct or prominent redox concentrations having a hue between 2.5YR and 10YR, value ≥5, and chroma ≥6. Between the soil surface and 12”, the Hydric Soil Indicators must be used. This is due to the amount of biological activity as well as the high organic matter content in Florida soils. Any contemporary redoximorphic concentration cannot have a hue that is 10R or more red, as this indicates a relict feature. This applies to hydric and non-hydric soils. Redox concentrations having a hue of 10R or redder would indicate relict wetness. So, to summarize for contemporary redox concentrations: 1.) The hues that can be used for non-hydric redoximorphic concentrations range from 2.5YR to 10YR to indicate concurrent wetness. 2.) The hues that can be used for hydric soil redoximorphic concentrations range from 2.5YR to 5Y, as long as the concentration meets the criteria of value and chroma for the element type being considered. For example, if the concentration were iron (Fe), the value and chroma would have to be ≥4. See hydric soil indicators for more information. Please note that gley colors are depletions not concentrations, so the gley charts would not be used to identify redoximorphic concentrations. Stripped Matrix. Another indicator used in sandy soils is the presence of low chroma colors where no matrix color appears to be dominant. This pattern appears as a splotchy, faintly contrasting arrangement of 2 or more colors of which at least one is low chroma and the others are relatively dull. In Munsell notation, these "dull" colors are defined as having a value of ≥5 and a chroma of 3 or 4. The boundaries between the colors are diffuse, which means that the color grades over ≥2mm. A clear boundary has a color grade over <2mm. A sharp boundary has a color grade that is not visible to the naked eye. This color pattern is called the stripped matrix. The stripped (lighter colored) areas must be at least 10% of the volume of the sample. The depth to the stripped matrix is used as the SHWT indicator more often in wet soils but can be applied even in better drained soils. In most areas of Florida, the stripped matrix may be difficult to identify because of its characteristic subtle color patterns. PLEASE SEE THE SECTION ON HYDRIC SOIL INDICATORS FOR MORE INFORMATION. Problems Identifying SHWT Indicators Stray Mottles and Microenvironments. The distribution and amount of mottles in a soil is extremely important for determining the depth to the seasonal high water table. Make sure the mottles are actually Redoximorphic Features. In many soils, the mottled zone begins gradually, and often a few stray mottles occur above a zone of substantial mottling. A stray mottle should not be used to estimate the SHWT (must be at least 2%). In addition to stray mottles, there are 13 sometimes micro-environments that contain gray matrix colors or features that appear to be mottles. These micro-environments may be golf ball size to basketball sized but the actual size is nearly impossible to determine from a bucket auger sample. A soil micro- environment may have formed as a result of a number of different factors, including soil disturbances by plants (e.g., decayed roots) or animals (e.g. burrows). This is only one of many reasons why a proper site evaluation requires more than one auger hole. Misidentification of Mottles. There is another important point to consider when using mottling as a SHWT indicator: MAKE SURE THAT YOUR MOTTLE IS A REDOXIMORPHIC FEATURE. In some sandy soils, layers of contrasting texture often have highly contrasting colors. The abrupt contact of a light colored, upper sandy horizon that tongues into a bright colored loamy or sandy layer below may be confused with mottling when observed in an auger sample. When a mottle is encountered that is the same color as the subsoil below, the suspected mottle should be examined carefully to see if it contains an increase in clay percentage as compared to the matrix. Some sandy soils contain a subsoil accumulation of clay that is distributed in fine lateral bands called LAMELLAE. Lamellae usually appear in contrasting colors, and are not normally indicative of wetness. And finally, in some cases, splotches of brown and red in a loamy or clayey soil might actually be called mottles but they are not drainage mottles and they are not indicators of the SHWT. Another possible problem is oxidized rhizospheres (root channels or roots). Even in well drained soils with no actual SHWT indicators, roots from plants will sometimes cause “mottles” to form around the roots. These are not indicative of the SHWT. However, in a HYDRIC SOIL, oxidized rhizospheres are indicative of the SHWT. We will discuss this later in greater detail. Estimating Drainage Classes in Spodosols Soils Without SHWT Indicators. Some sandy soils lack the obvious SHWT indicators such as high chroma or gley redoximorphic features. Most often, this deficiency is observed in spodosols. A spodosol has a horizon sequence consisting of a topsoil layer (an ‘A’ horizon), normally underlain by a lighter layer (an ‘E’ horizon), underlain by a slightly hardened, darkly colored layer (a ‘Bh’ horizon) called a SPODIC horizon. As a general rule, the spodic layer has a value 4 and a chroma 3. This must occur below the ‘A’ horizon. The spodic horizon formed as rainwater washed tea-colored humic acids from decaying plants and down through the porous sandy soil. Here the "tea" sloshed up and down with the fluctuating water table for many hundreds of years, coating the sand grains to form the spodic horizon. In Florida, while the spodic horizon also contains a substantial amount of aluminum, iron is usually deficient and therefore iron oxide mottling is absent. A stripped matrix might be present, but recall that this indicator is often difficult to identify. Where high chroma mottles are present within the actual spodic layer, they are not a reliable seasonal high water table indicator. Normally, the seasonal high water table is above these mottles. The Depth to Spodic Fallacy. In the past, some persons estimated the SHWT in spodosols to be the depth where the spodic horizon begins. While it is generally true (but not always) that the SHWT is somewhere above the spodic horizon, an exact correlation usually cannot be made with the depth to the top of the spodic horizon. Conceptual Drainage Models. When the SHWT indicators are not obvious, or are difficult to interpret, a good way to find support for an uncertain estimate is to organize spodosol data from the soil survey in a conceptual model for landscape position and drainage. By studying and learning the morphological differences between spodosols of differing landscape positions, a drainage sequence can be constructed and used to estimate general SHWT classes. The most commonly occurring spodosol drainage sequence in Florida, from wettest to driest is given in the following table. The wettest spodosol of the sequence is ‘a.’ and the driest is ‘d’. Note in this sequence that as the soil gets better drained, the subsurface layer becomes lighter and the subsoil layer changes in color from black or brownish to reddish and finally yellowish. This is a broad, generalized model only and there are many variations and substitutions possible. 14 Conceptual Drainage Sequence for Spodosols in Florida a.1. Thick, very dark colored surface, grayish or no apparent subsurface, black or dark colored spodic horizon. SHWT at about 0 to 6 inches below soil surface. a.2. Thick, very dark colored surface, grayish subsurface, sometimes stripped with a deep, black or dark colored spodic horizon often beginning below 50 inches. SHWT at about 0 to 6 inches. b. Grayish or salt and pepper surface, light gray subsurface, reddish brown or dark brown spodic horizon. SHWT at about 6 to 18 inches. c.1. Light gray or light salt and pepper surface, white subsurface, reddish brown gradually changing to yellowish brown spodic horizon. SHWT at about 18 to 42 inches. c.2. Light gray or light salt and pepper surface, white or light yellowish subsurface grading to white or light gray, brown spodic horizon below 50 inches. SHWT at about 18 to 42 inches. d. Thin, very light gray or light salt and pepper surface (that is sometimes not discernible from the subsurface), white subsurface tonguing abruptly into a brownish yellow subsoil with a thin spodic layer at contact of the white subsurface and brownish yellow subsoil. Underlying layer gradually lightens to white and may have bright mottles. SHWT at about 40 inches or greater. Vegetation and SHWT Vegetation is a natural indicator that can help provide confidence in a SHWT estimate, but should be used carefully because there are so many "exceptions to the rule" and because vegetation is so easily and quickly changed by natural and human forces. A section on vegetative indicators will be featured later in this manual. Organic Matter Content and SHWT The presence of organic matter in a soil may also be helpful in estimating the SHWT of a soil. Organic matter, which darkens the mineral soil, does not fully decompose in wet soils. If a soil has a dark colored surface composed of fully decayed plant material, called MUCK, the SHWT is at or above the soil surface. Muck imparts a slightly sticky, often greasy feel to the soil material (it is often confused with clay or silt). It is usually black or dark brownish colored. If the texture is not muck, but there is enough muck in the surface to modify the textural class (i.e., mucky sand), then the seasonal high water table can be predicted to be at or slightly above the soil surface. To determine the amount of organic material in these types of soils one must use the “Near-saturated Soil Rub Test” which IS NOT the same as texturing mineral soil. In this test, the material is wet enough to squeeze water out of the sample. If, after two light quick rubs between your thumb and forefinger, the soil feels gritty (meaning dominated by sand particles), the soil is neither muck or mucky mineral, it is mineral. If, after three MORE light quick rubs, the soil feels either gritty or plastic, the soil is not muck, it is mucky mineral. Only after not feeling grit or plastic after at least 6 rubs (preferably 10) should the soil be considered to be a muck. Lesser amounts of organic matter, which may be easier to see than to feel, can be used to predict seasonal high water table depth. A black surface for example, usually has a SHWT within 12 inches. A very dark gray surface usually has a SHWT at about 12 (9-15) inches. Dark gray is usually >15 inches. USDA Drainage Classes Soils with similar SHWT's are often grouped into broad categories called DRAINAGE CLASSES. It must be emphasized that correlation of these classes to SHWT ranges is generalized and drainage class should never be given when depth to the SHWT is requested. There are six classes commonly used in Florida. VERY POORLY DRAINED soils generally have SHWT's at 0 to 24 inches above the surface. POORLY DRAINED SOILS generally have SHWT's at about 0 to 18 inches below the surface. SOMEWHAT POORLY DRAINED soils generally have SHWT's at 12 to 30 inches below the surface. MODERATELY WELL DRAINED soils generally have SHWT's at 24 to 48 inches below the soil surface. WELL DRAINED soils generally have SHWT's at 60 inches or more. The well drained class is rarely applied to soils that are sandy throughout. EXCESSIVELY DRAINED soils are always sandy throughout and have a SHWT greater than 72 inches below the surface. 15 USING THE SOIL SURVEY Nearly every county in the state of Florida has a published soil survey. The soil survey is an extremely valuable reference and every environmental health specialist must have his or her own copy. There are three basic parts to the soil survey. They are the soil maps, the interpretive and data tables, and the informative text. A brief primer called "How To Use This Soil Survey" is located on the inside cover of each modern soil survey publication. There is now a Web soil survey that supersedes any legacy documents (printed copies of soil surveys). The best way to get to the web soil survey is to go to a search engine and look up “web soil survey” and find the one from the USDA NRCS.. The current web address is http://websoilsurvey.nrcs.usda.gov/app/. Detailed Soil Maps Maps, Symbols, and Legends. The detailed soil survey maps are located in the back of the published soil survey. The map "base" is an aerial photograph. Lines have been placed on the photograph that DELINEATE or encircle a type of soil that differs from the type of soil on the outside of the delineation. Inside each delineation there will be a numerical symbol (sometimes an alpha character group in older soil surveys) that identifies the soil type. To find out the name of the soil represented by the numerical symbol, turn to the page at the beginning of the set of soil maps and refer to the SOIL LEGEND. Note that to the right of the soil legend, on the same fold-out page, there is a CONVENTIONAL AND SPECIAL SYMBOLS LEGEND. All of the other symbols that might be drawn on the detailed maps are defined in this legend. For example, a narrow perennial stream (one that flows almost all of the time) is denoted by a dash-dot-dash-dot pattern that traces the stream's course. The detailed soil survey sheets are called ATLAS SHEETS or MAP SHEETS. The atlas sheet is usually identified by a page number in the upper left hand or upper right hand corner, directly over an arrow that points north. The atlas sheet number is encircled by a bold line. Map Scale. On the bottom or side of the atlas sheet, there is a ruler-like SCALE that graphically depicts the length of a mile and a kilometer on the detailed map. Note that below the ruler scale, a written scale appears. For example, the line might say SCALE 1:24,000 (one to twenty-four thousand). This means that one inch on the map equals 24,000 inches on the ground. This can be converted mathematically to one mile equals 2.64 map inches OR one map inch equals 0.3787 miles equals 2000 feet. Most Florida soil surveys will have scales of 1:24,000 or 1:20,000. Some older surveys may have somewhat different scales. Mostly the scales range generally from 1:15,000 to 1:24,000. Finding A Location On Soil Survey Maps Perhaps the most difficult part about using the soil survey is locating a point on the detailed map. There is absolutely no substitute for experience, and experience can only be gained by practice in locating points. Getting Started: Index to Map Sheets. Directions to a field site may consist of a set of written instructions, or perhaps a crudely drawn map. It is usually best to then locate the general area of the site on a county map that you are comfortable using. Next, turn to the INDEX TO MAP SHEETS located in the soil survey on a fold out page just before the set of detailed maps. Note that a county map has been blocked out into forty or more rectangles. Each rectangle represents the area mapped on a detailed atlas sheet, and the number in the left hand corner of the rectangle is the atlas sheet number. Use this index to locate the general area of your site. Then turn to the correct atlas sheet. Aerial Photos and the Changing Landscape. Because so many areas in Florida are rapidly developing, landscapes photographed from the air can change dramatically in a short period of time. This is why it is important to be familiar with the date of the aerial photograph. The date of the photo is located on the atlas sheet, often on the inside margin. Most soil survey photography will be at least 5 to 10 years old. If an area has developed intensely, finding a point will not be easy for an inexperienced soil survey user. Geographic Reference Points. The first step is to find a familiar starting point on the atlas sheet. The best reference point is often the intersection of two numbered roads. Small named lakes and ponds, other named features, and land boundaries make good reference points. Using a favorite county map, look for familiar shapes and patterns (i.e., the shape of a parking lot or pattern of roads in a development). Measuring Distances on the map. In many instances, it will be necessary to use a ruler or scale to measure the distance to a turn from the last known point. For example, a written instruction might say to" turn south from the intersection of two roads, go 0.3 miles and turn left, then go 0.4 miles to the lot on the right". If the atlas sheet scale is 1:24,000, then it is known that one 16 mile equals 2.64 inches. Divide 2.64 by ten to get the distance for one tenth of a mile. This equals 0.264 inches. Then, to get the 0.3 mile distance given in the directions, multiply 0.264 by 3 to get the result that three tenths of a mile equals 0.792 inches, or about 0.8 inches. Complete the conversion in a similar manner for the other distance. The map directions now read "turn south from the intersection of the two roads and go 0.8 inches, then go about 1 inch east to the lot on the right. Locate the point and identify the soil. Land Survey Systems Locations or parcels of land are often referenced using a land survey system. Two types of land survey systems are commonly used to describe land ownership. They are the metes and bounds system and the U.S. Public Land Survey (PLS). Metes and Bounds. The metes and bounds system describes the boundaries of a parcel of land referenced by compass settings or geographic features such as shorelines and named roads. This system is generally not useful for locating specific points. Here is an example of an older metes and bounds parcel description: “Begin at the confluence of Red Creek and the South River and proceed along the shoreline of Red Creek to the point where it intersects with Oldtown Road, following Oldtown Road to the intersection with South River, then along the shoreline of South River to the starting point.” U.S. Public Land Survey. The U.S. Public Land Survey is a system that uses a grid originating at the intersection of a north-south line and an east west line, analogous to lines of longitude and latitude. The north- south lines are called meridians, or range lines. The east-west lines are called parallels, or township lines. The origin of the grid is formed by the intersection of a principal meridian with the intersection of a principal parallel, or base line. The principal meridian used in Florida is drawn through Tallahassee and is called the Tallahassee Meridian. The principal parallel used in Florida is called the Tallahassee Base Line. It runs approximately from Jacksonville to Pensacola. Additional parallels and meridians are added to form the grid. These additional lines are about 6 miles apart. They enclose a 36 square mile area called a sectionalized township. Each sectionalized township is further divided into 36 individual 1 square mile areas called sections. All of the land area in a strip bounded by a meridian to the west and a meridian to the east, lies within the same numbered range. The ranges that lie west of the principal meridian are numbered in succession as follows Range 1 West (abbreviated R.1W), R.2W, and so forth. The ranges that lie east of the principal meridian are numbered similarly: R.1E, R.2E, R.3E. Townships identify strips of land that extend from east to west, bounded by parallels, and they are numbered in the same method used for ranges: T.1N, T.2N, T.3N, and T.1S, T.2S, etc. The intersection of all the land that lies within an individual range and an individual township is the 36 square mile area called the sectionalized township. Each sectionalized township is identified as in the example: R.1E T.3S. Each of the 36 individual 1 square mile parcels in the sectionalized townships, called sections, is identified by a number. The numbering of the sections begins with 1 in the northeastern most section in the sectionalized township and ends with 36 in the southeastern most section in the sectionalized township. 17 Each section can be further subdivided, most commonly in increments of quarters. Each quarter of a section, can also be subdivided by quarters, as can each successive subdivision. The following designation of a parcel of land is read: SW1/4, NE1/4, NW1/4, Sec. 35, R.2E. T.3N. as “the southwest one quarter of the northeast one quarter of the northwest one quarter of section 35, range 2 east, township 3 north.” Using the PLS with maps. A clear plastic grid guide is useful for determining the PLS location of a parcel. The guides contain printed lines that divide the section into quarters, divide each quarter again, and divide each quarter one more time. It is extremely important that the scale of the guide corresponds exactly with the scale of the reference map. Some guides contain a grid for only one scale, while others contain a guide for several scales. The guides often list the acreage of a cell for each subdivision. A perfect section is equal to 1 square mile which is equal to 640 acres. A quarter section will therefore be equal to 160 acres, and this parcel quartered will yield 4 parcels, each containing 40 acres. When locating specific points on a map (as opposed to parcels of land), it is often best to specify the point by the distance in 2 cardinal directions from the closest corner of the section in which the point lies. For example, a point might be referenced: 625 feet south and 1220 feet east of the NW corner of section 3, R.4E. T.7S. Using the PLS with the soil survey. All of the photography that appears on a single soil survey atlas sheet is bordered by a solid line called a match line. One township or range is divided from the adjacent township or range by a single dash that is oriented perpendicular to the match line and the township or range is identified as in the example: R.21E.|R.22E. . The corners of each section are marked by a large plus sign (+). A bold section number is placed as near to the center of the section as is practical. Although section corners are placed on the soil survey atlas sheet as accurately as possible (usually within 100 feet), their use in the document is intended to be for reference only. Land Grants. Because the U.S. Public Land Survey was authorized by the Land Ordinance of 1785, earlier land survey systems had already been in place. In Florida, British and Spanish Land Grants had established land boundaries that had been in place for over a century in some cases. These land grant boundaries are still in existence today, and supersede the section boundaries of the PLS . For a parcel of land surveyed by a land grant, the section number is replaced by the land grant number, as in the example: Land Grant 66, R.2E. T.3N. It is generally not appropriate to describe quarters of the land grant because few of the land grants are square. Land Grant numbers are always greater than 36 so that they are not mistaken for PLS section numbers. Land grant boundaries are often delineated by a dashed line separated by two dots (---- ----), while only corner points delineate a PLS section. 18 The Soil Survey Text Map Units. The numeric or alphabetic symbol that identifies the type of soil on the atlas sheet actually identifies an entity called the MAP UNIT. The map unit may include 2 or 3 soil types, only one soil type, or possibly a land type that does not include any soil type. "Urban land" for example is a map unit that includes mostly parking lots and city buildings. Map Unit Descriptions (MUD’s). Refer to the "Detailed soil map units" section of the text (see the CONTENTS section in the beginning of the publication). The written descriptions of the map units are arranged in numerical order. Turn to the description for map unit number of interest. The order of the data presented in the map unit description will be the same for every map unit in the county. Most often, the map unit name is the conjugation of a soil series, soil texture, and slope class. The texture in the map unit name identifies the most common surface texture for the map unit in the survey area. The opening paragraph identifies the slope class, the drainage class, the landscape position that the soil is on, and the general shape and range in size of the delineations. The second paragraph gives a non-technical description of the soil profile. Inclusions. The third paragraph talks about INCLUSIONS. All map units contain inclusions. An inclusion is a kind of soil that differs from the one named in the map unit title. Sometimes there are soil inclusions in a map unit delineation because an area of the different kind of soil is too small to encircle with a pencil line. Note that to be delineated on a soils map, a particular soil type must be at least 6mm square (1/16 sq. inch). Maps with smaller scales usually have delineations commonly 1.5-2 times the size of the minimum area that can be shown. For example, on a 1:20,000 scale, the minimum size delineated is 4 acres, while on a 1:24,000 scale, it is 5.7 acres. Other times it is a transition soil found near the edge of the delineation. For the map scale 1:24,000, the printed line used to encircle the delineation of soil is 50 feet wide in real life! Be sure to note in this paragraph that the types of inclusions are identified by name so that they will be easier to identify if encountered in the field. INCLUSIONS ARE THE PRIMARY REASON WHY ON SITE SOIL INVESTIGATIONS ARE REQUIRED TO SUPPLEMENT SOIL SURVEY DATA. Physical Data in the MUD. Next find a paragraph that gives physical data for the soil. Available water capacity, permeability, and water table data are generally given. If data is grouped by a class, the class data range will be identified in the glossary. For example, if the permeability is given as moderate, turn to the glossary and look up "permeability". The glossary entry will provide a table showing that moderate permeability equals 0.6 to 2.0 inches per hour. Vegetation in the MUD. Another paragraph describes the natural vegetation that grows most often in areas of the specified map unit. The last several paragraphs discuss limitations and potentials for specified land uses including major crops grown on the soil and urban land uses. Technical Soil Descriptions. To read a technical description of the soil series components of map units in the county, turn to the section entitled "Classification of the Soils". Preceding an alphabetically arranged set of soil series descriptions, note the short introduction to the soil classification system used by the USDA Natural Resources Conservation Service. Like the map unit description, the technical description uses a standard format for each soil series described. The technical description is also called the taxonomic unit description or the series description. The last sentence of the introductory paragraph always gives the taxonomic classification for the soil. The third paragraph begins the actual soil profile description, written in technical terminology. Following the description, the range of characteristics describes the allowable variation in horizon thicknesses, colors, textures and other parameters for the soil series. Use and Management of the soils. The types of information presented in the interpretive data tables are discussed in a text section entitled USE AND MANAGEMENT OF THE SOILS. Information such as county land use data, soil map units used for certain land uses, and practices used to overcome soil limitations are given in this section. Subsections are usually written for cropland, rangeland, woodland management, windbreaks, recreation, wildlife habitat, building site development, sanitary facilities, construction materials, and water management. The individual subsections also discuss the interpretive table ratings for the specified land use. Soil Properties Section. The types of information presented in the data tables are discussed in a text section entitled SOIL PROPERTIES. Engineering index properties, physical and chemical properties, soil and water features; physical, chemical and mineralogical analyses of selected soils, and engineering index test data are some of the titles of 19 subsections that discuss everything from laboratory methods, local data, and other classification systems. This brief portion of the soil survey text is intended primarily for the advanced professional user. Soil Survey Tables The TABLES section of the soil survey is located between the detailed soil maps and the text. There are two basic types of tables. They are DATA TABLES and INTERPRETIVE TABLES. Generally, the first data table is "Temperature and Precipitation". Use this table to learn how rainfall is distributed throughout the year and when the highest water tables might be expected in years with normal rainfall patterns. Note carefully the data table entitled "acreage and proportionate extent of the soils". Use this table to find out which soils are most extensive in the county. Read the map unit descriptions for these soils carefully. Many of the interpretive tables that follow are agricultural. They give yield data and limitations for the specified use. The urban land use tables give a rating of slight, moderate or severe for the components of each map unit and also give a reason for moderate and severe ratings. In the "sanitary facility" table, septic tank absorption field ratings will often seem more restrictive than might be expected under Florida law. The last table appearing in this section is the engineering and other laboratory data. Be sure to consult the Soil Properties section of the text. The table "Soil and Water Features" will probably be most useful. This table contains data on flooding potential and water tables. Water table data here is often more generalized than given in the map unit description. If there is a difference between tabular data ranges, and map unit data ranges, use the data range given in the map unit description. The General Soils Map Find the color fold-out county map preceding the detailed soil maps. This is the General Soils Map. Delineations on the general soils map show broad areas of the same GROUP of soils. The general soils map unit is named after the two or three most extensive soils in the unit. An example is the Candler-Tavares-Apopka association. The general soils map unit description also identifies other minor soils commonly found in the general soil map unit area. Often, the general soils map unit lines correspond to lines on geomorphic or physiography maps. Several general soils map units might be grouped into even a broader category. For example, the Candler- Tavares-Apopka association and Zolfo-Tavares association could be in the broad legend category Soils of the Uplands. When conducting a soil investigation in a general soils map unit called Zolfo-Tavares association, note that there is a description of the geologic landform where the soils are found. The Zolfo-Tavares association is on uplands at a lower elevation than the main ridges of the county. Landscape positions are also given for the individual soil components of the general soils map unit. Using this information, it is possible to construct a landscape model that can be drawn on paper and used for reference. In the Zolfo-Tavares association, Tavares is the on the highest landscape position along with the minor soil Millhopper. Zolfo soils are on the next lowest landscape position along with Adamsville and Sparr soils. Myakka soils are on the lowest landscape positions. The landscape model can be used in the field to predict inclusions to the mapped soil especially when there is a noticeable landform change. In conclusion, each environmental health specialist should have a personal copy of the soil survey. Sites should be marked, and there should be notes in the margin. A successful site investigator often uses the soil survey for reference. Web Soil Survey The current official soil survey for the nation is the Web Soil Survey, which was created by the USDA NRCS. The following address will take you to the current site. http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm This site will let you find current properties with much more current photography. There are different ways with which to navigate the system. Please go to the site and start using it. Should you have questions please contact a co-worker or your departmental program consultant. Soil Series Name Search This site will allow the user to type in a name of a soil and retrieve the classification information on the soil. It is highly useful to all as it is the more updated resource than some of the older soil surveys. The following address will take you to the site. https://soilseries.sc.egov.usda.gov/osdnamequery.asp This site is particularly useful if a county health department receives a soil profile with a series name that is unfamiliar to them. All that needs to be done is to type the soil name into the blank, hit “process” and then “view description” to obtain the technical soil 20 description. If you have questions regarding this, please contact your departmental program consultant. Older Soil Surveys The soil survey program began in the United States in the 1890's. Some Florida soil surveys were published in the first decade of the 1900's and, unfortunately, some still have not been replaced by a modern soil survey publication. The good news is that only a small number of counties in Florida lack a modern publication. Older soil surveys are not obsolete. Modern soil surveys are better because of the technological advancements in the second half of the 20th century that have increased our knowledge base and given us better tools to work with. Currently, the Web Soil Survey is the official soil survey for the entire nation. In general older soil surveys are less useful because: 1. they don't include as much data (for example they may lack soil characterization data); 2. the methodologies of soil survey have changed (for example, the soil classification system has changed); Changes in methodologies may be so drastic that data compared between an older and modern soil survey appear to be in contradiction. One such apparent contradiction is the difference in SHWT ranges. The difference exists because in general many more soil series are recognized now and the older soil series simply encompassed a wider range of characteristics. For example, currently the Lakeland series has a SHWT that is greater than 80 inches and it has a texture throughout of sand or fine sand only. At one time the Lakeland series had a texture range of loamy fine sand to coarse sand with or without finer textured subsoils that began at various depths as shallow as 30 inches. A water table could be perched above the subsoil at any depth. Now there are over 20 soil series that cover this same range of characteristics. If a modern soil survey or interim report does not yet exist, the best way to accommodate the older soil survey is by obtaining supplemental data and/or special training from the Natural Resources Conservation Service. In many areas, supplemental data correlates new information with the soil series and map units of older surveys. Ask the local NRCS office if this information is in a format for distribution. In some cases, a special workshop may be requested to discuss the data in the older publication. Conversion of Old Horizon Designations Before about 1981, soils surveys and other documents contained profile descriptions that used a slightly different group of horizon designations. A list of some old designations and their equivalent designations in the new system is shown. Old New O1 Oi or Oe O2 Oa or Oe A1 A A2 E A3 AB or EB AC AC B1 AB or BA B2 B or Bw B3 BC or CB Horizon numbering in the old system is the same as in the new system, however the inclusion of numbers in old master horizon designation makes interpretation somewhat confusing. Consider the following example: Old New A11 A1 A12 A2 A21 E1 A22 E2 B21t Bt1 B22t Bt2 21 VEGETATION AND SOILS There is an intimate relationship between soil type and vegetation type. Plants have varying nutrient and water requirements, just as different soils have varying nutrient and water contents. Therefore, recognizing certain vegetative clues can help us predict certain soil characteristics. The cypress tree, for example, almost always grows in soils that have a seasonal high water table at or above the surface. Ecological Plant Communities. There are few specific soil-vegetation relationships that are as easy to recognize and use as the cypress example given. Some relationships change in different areas of the state. A good general way of using the soil-vegetation relationship is by grouping plants in communities. There are many plant community classification schemes, but the one that will be considered here was developed by the Natural Resources Conservation Service in Florida. This soil based system organizes vegetation into ECOLOGICAL PLANT COMMUNITIES. This is a generalized classification scheme and does not seek to provide detailed classes for the entire range of variation possible in Florida plant communities. Some of the more rare plant communities will not be considered in the following discussion. In addition, some communities have been grouped together for the purpose of this manual. Be reminded that recognition of plant communities can assist in the decision making process but there is still no substitute for a soil investigation. Coastal Strand. These communities of north and south Florida are adjacent to the gulf and ocean. They consist primarily of dunes, swales and beaches. Soils are generally sandy throughout with droughty soils on dune ridges and wet soils in the lowest swales. These soils generally lack much profile development. There are few good specific vegetative indicators. Look for plants like Spartina patens (saltmeadow cordgrass), black needlerush, and Spartina alterniflora (smooth cordgrass or saltmarsh cordgrass) in the wet areas. If protected from salt spray, some wet swales may contain Swamp or Pond vegetation. Sand Pine Scrub. This community is recognized for its even-aged stands of sand pine or thick scrubby oak growth. This community is found throughout the state, from the coast to inland sites. Generally, soils are somewhat poorly drained to excessively drained. Commonly, the excessively and well drained soils have weakly developed spodic characteristics including a yellowish subsoil beneath a white, leached subsurface. Drier sites have a sparse understory, and wetter sites have a thicker understory. There are few areas in this community that have wet soils. Rosemary is a plant more associated with the driest sites in this community. Some areas of this community are locally called the "sandhills". Longleaf Pine-Turkey Oak Hills. This community is also found in areas called the sandhills. Landscapes are generally rolling lands with level to strong slopes. Vegetation is dominantly longleaf pine, turkey oaks, with a sparse understory of wiregrass. The soils are generally sandy throughout, and well drained to excessively drained. Some soils have a loamy subsoil below a thick sandy surface. Wetter soil inclusions are often easy to identify because they are on an obviously lower landscape position. Mixed Hardwood and Pine. This community grows almost exclusively in the upper Florida Panhandle. It is much like the typical hardwood forest that northern tourists don't expect to find in Florida. The landscapes are nearly level to sloping, and the soils have shallow, loamy to clayey subsoils. The soils are generally moderately well drained to well drained. Older communities often have a relatively open understory. Dominant trees are beech, maple, oaks, magnolia, hickories and holly. Flatwoods. These plant communities are broad flat lands supporting mostly saw palmettos and pine trees. In the south Florida condition, they are much like a savannah with only scattered pine trees and extremely thick palmetto growth in their natural state. In north Florida, there is likely to be a thicker stand of pine trees and the understory is usually mixed with other shrubs like wax myrtle and gallberry (North Florida Flatwoods). Other variations of this plant community include areas where south Florida slash pine dominates the sparse overstory, where cabbage palms replace slash pine (Cabbage Palm Flatwoods) or where tropical vegetation is included and soils are underlain by limestone at shallow depths (Everglades Flatwoods). Except in the Everglades Flatwoods, soils are poorly to somewhat poorly drained. The classic soil is a spodosol such as the Myakka series in south Florida and the Leon series in north Florida. Some soils have a loamy subsoil, but rarely is there a shallow clayey subsoil. 22 Upland Hardwood Hammocks. This community is mostly in central and northern peninsular Florida. It is usually on rolling terrain with nearly level to strong slopes. It is similar in many respects to the mixed hardwood pine community, but it generally lacks pine trees, or contains very few. The understory is commonly sparse and open. Common trees are beech, magnolia, live oak, laurel oak, holly, black cherry and dogwood. Soils are generally somewhat poorly drained to well drained with sandy surfaces and loamy to clayey subsoils. Wetland Hardwood Hammock. This community grows predominantly just inland, but generally parallel to the Big Bend coast from Wakulla county to Pasco county. The landscape is nearly level and the soils are poorly to somewhat poorly drained, with sandy surfaces and loamy to clayey subsoils. The soils are often alkaline, and shallow limestone is found in many areas. The vegetation is luxurious with thick canopies of evergreen and semi-evergreen deciduous trees. The trees include live oak, laurel oak, red bay, sweetgum, and magnolia. In some areas, red cedar is the dominant tree. Swamps. The ecological communities that grow in swamps will not be described in detail here. These include Scrub Cypress, Cypress Swamps, Mangrove Swamps, Swamp Hardwoods, and Shrub Bog-Bay Swamps. They are on nearly level landscapes with a variety of very poorly drained soils and sometimes a few poorly drained soils. Remember that if there are cypress trees, the site is likely to have soils with seasonal high water tables at or near the surface. A plant identification handbook should be used to identify and learn about other plants that are indicators of very poorly drained soil conditions. Bottomland Hardwoods. This community is on the floodplains of the large north Florida rivers. The landscape is nearly level along the river courses and often ends abruptly at higher, non-flooded landscapes. Soils are generally somewhat poorly drained to very poorly drained with flooding that occurs mostly in the winter and spring. In many areas, the vegetation looks like that in other hardwood communities, so it is probably best to learn to recognize this landscape. Pitcher Plant Bogs. This community is on flat landscapes that resemble a savannah. There are scattered pines, bay trees, and shrubs with thick grass and sedge growth containing numerous patches of pitcher plants. Pitcher plants are a good wet soil indicator. The soils in this community are usually very poorly drained, but can also be poorly drained. They are usually sandy but may have a loamy subsoil. Sawgrass marsh. This community is the wet, nearly level grassland of the Everglades. Sawgrass is a good wet soil indicator. Trees are rare, and in fact the community is often a monotype of sawgrass. The soils are very poorly drained, and they are often Histosols. Freshwater marsh. This community is usually easy to recognize because it is essentially a shallow pond landscape. The landscape is covered with water most of the time and the vegetation generally does not include trees or shrubs. Look for maidencaine, reeds, and rushes. The soils are very poorly drained and are often Histosols. Salt Marsh. This community occurs along the Gulf and Atlantic coasts adjacent to rivers and bays. In estuaries, it often transitions gradually to freshwater marshes. The landscape is flat and usually flooded daily by tides. Vegetation consists primarily of grasses, sedges and rushes. The soils are very poorly drained and are often Histosols. They often contain high contents of sulfur and emit a characteristic rotten egg odor. Sloughs. This community is often difficult to recognize. Part of the problem is that the word slough has so many different connotations to different people. For our purposes, the slough is a long, relatively narrow or strand-like, open expanse of grasses, sedges, and rushes. It often contains scattered trees and shrubs. It is nearly level, and the soils have a water table at or near the surface during the rainy season. Water on the surface of this landform often flows slowly towards an outlet. Representative soils in the slough community have sandy surfaces or are sandy throughout and often have a weakly developed spodic-like subsoil that varies in color from yellowish to brownish. The slough is primarily a south central and southern Florida community. Cutthroat Seeps. This community is on nearly level to gently sloping landscapes, mostly in Polk and Highlands counties. The vegetation is savannah-like with a dominance of cutthroat grass and other grasses and scattered shrubs, slash pine, saw palmetto and wax myrtle. The soils are usually poorly drained spodosols. Occurrence and Density of Vegetative Indicators. There are many good individual plant indicators for a variety of soil conditions. Many of these indicators are more useful in some parts of the state than others. It is not only the occurrence of an individual plant but also 23 the density of the occurrence that can be important. For example, one turkey oak on a site might just indicate an exception to the rule but a small community of turkey oaks growing in an area thought to be poorly drained is likely to indicate a slightly drier site. Please go to the following link for a listing of plants from the USDA NRCS. http://plants.usda.gov/ Non-Water Table Factors. Changes in vegetation can provide other clues about soil conditions in addition to the SHWT. In some areas of Florida, an abundance of eastern red cedar and cabbage palms is a clue that the underlying limestone is at a shallower depth. The occurrence of salt tolerant plants such as black needle rush might indicate that the site is occasionally inundated by the tides or subject to salt spray. Non-Soil Factors. It is important to remember however that factors other than soil conditions affect the occurrence and density of certain plants. Management by humans, natural succession, lightning caused fires, animal populations, insect pests and many other factors can influence the vegetative characteristics of a site or area. Experience in an area is by far the best help for effective use of plant indicators. Learn how to identify plants through the experience of others, attending formal training sessions and by obtaining a guide book for plants in Florida. Vegetative characteristics alone should be used only in rare instances to predict SHWT's. Remember, exceptions to the rule can be very common in some areas of the state. METHODS OF SOIL INVESTIGATION The following methods and procedures can only be used successfully if the information presented previously in the Florida Soils Manual is fully understood. Consult the manual and the published soil survey (if one is available) frequently. Discuss observations made during your site investigation with co-workers or supervisors. Request assistance from a soil scientist when unusual soil conditions are encountered. There is no substitute for practice and experience. Obtaining Soil Survey Data The official soil survey for the nation is the Web Soil Survey. It should be used in place of the printed (legacy) copies. These legacy documents are still good sources of information and can be taken into the field to help identify the soils that actually exist on site, which often are inclusions of different soil series. They also are an excellent source of older aerial photography. When using the legacy documents, the following methodology should be used. 1. Find and record the soil survey data that will be used for all site investigations. This step needs to be taken only once and the information obtained should be committed to memory and/or recorded in a convenient location in your copy of the soil survey (such as on the inside cover). The date that the aerial photography was taken for the atlas sheets is usually located on the inside margin of each atlas sheet page. The atlas sheet scale