Maryland Envirothon Soil Study Guide PDF 2002-2017

Compiled by the Maryland Envirothon Soils Workgroup September 2002 Dan Bard – Maryland Department of Agriculture Barry Burch – Frederick County Board of Education Carl Robinette – USDA, Natural Resources Conservation Service Elmer Weibley – Washington County Soil Conservation District Chad Wentz – U...

Compiled by the Maryland Envirothon Soils Workgroup September 2002 Dan Bard – Maryland Department of Agriculture Barry Burch – Frederick County Board of Education Carl Robinette – USDA, Natural Resources Conservation Service Elmer Weibley – Washington County Soil Conservation District Chad Wentz – USDA, Natural Resources Conservation Service Lenore Vasilas-– USDA, Natural Resources Conservation Service Revised 2017 by James Brewer - USDA, Natural Resources Conservation Service Introduction Sustaining our soil productivity and the management of our other natural resources is an important concern of farmers, rural landowners, homeowners and governmental agencies. This document will provide the scope by which farmers and landowners utilize soil and water conservation plans to maintain these important resources. It will also identify best management practices that will conserve, protect and enhance their land. As soil scientists analyze and examine soils, they believe texture is the most important aspect of a soil. By determining a soil’s texture, an individual is able to characterize the interrelationships among the other soil properties of the soil. Hence, the individual is better informed as to the ability and the uses of the land. Stated below are objectives that an individual can learn to improve their awareness and knowledge of soils and its capabilities: 1. Recognize the factors affecting soil formation and the composition of the soil. 2. Identify the various landforms and associated soil parent materials. 3. Identify in the field soil properties (such as texture, depth of bedrock, seasonal high water table, flooding, slope, etc.) that directly impact soil interpretations. 4. Utilize the soil survey to develop an assessment of the limitations for regional land us planning. 5. Develop an understanding of the soil properties that affect soil health and soil quality. 6. Determine the health and quality of the soil in the field. 7. Develop an understanding of, and the ability to apply the Land Capability Classification System in an effort to protect farmland from urban pressure. 8. Develop an understanding of the soil’s impact on the hydrologic cycle. We encourage the use of this document to develop a better understanding of soils, the factors associated with soils development, and its uses, as well as soil conservation districts and the various means to control soil erosion and water quality degradation. Table of Contents Soils Map..................................................................................................................Page 1 Soils Descriptions – Non-Technical.........................................................................Page 2 Overview..................................................................................................................Page 6 Soil Composition......................................................................................................Page 7 Factors of Soil Formation.........................................................................................Page 8 Parent Material....................................................................................................Page 8 Climate................................................................................................................Page 10 Living Organisms................................................................................................Page 11 Landscape Position..............................................................................................Page 11 Time.....................................................................................................................Page 14 Soil Forming Processes............................................................................................Page 14 Soil Features.............................................................................................................Page 18 The Soil Profile...................................................................................................Page 18 Soil Horizons.......................................................................................................Page 19 Color....................................................................................................................Page 23 Organic vs. Mineral Soil Material.......................................................................Page 28 Mineral Soil Texture (USDA).............................................................................Page 28 Rock Fragments...................................................................................................Page 32 Soil Structure.......................................................................................................Page 33 Permeability.........................................................................................................Page 34 Depth...................................................................................................................Page 35 Reaction...............................................................................................................Page 37 Drainage..............................................................................................................Page 37 Available Water Capacity....................................................................................Page 43 Erosion.................................................................................................................Page 45 Erosion Potential.................................................................................................Page 46 Land Capability Classification............................................................................Page 47 Other Management Interpretations......................................................................Page 52 Soil Surveys..............................................................................................................Page 53 General Soil Information.....................................................................................Page 54 Detailed Soil Information....................................................................................Page 55 References................................................................................................................Page 56 Agricultural Best Management Practices.............................................................Page 57 Grassed Waterway....................................................................................................Page 58 Contour farming......................................................................................................Page 59 Crop residue management.......................................................................................Page 60 Crop rotation............................................................................................................Page 62 Cover crop...............................................................................................................Page 63 Nutrient management..............................................................................................Page 64 No-till farming.........................................................................................................Page 65 Soil Health................................................................................................................Page 66 Soils in the Urban Landscape................................................................................Page 70 Maryland Envirothon Soils Exam Guidance Information.................................Page 71 Outland to Soils Exam.........................................................................................Page 71 Guidance to Soils Exam......................................................................................Page 113 Maryland Envirothon Soils Scorecard Example.................................................Page 131 1 Soil Descriptions - Non-Technical Anywhere County, Maryland Only those map units that have entries for the selected non-technical description categories are included in this report. Map DsB - Duffield silt loam, 3 to 8 percent slopes Description Category: SO5 THE DUFFIELD SERIES CONSISTS OF VERY DEEP AND DEEP, WELL DRAINED SOILS ON UPLANDS. THEY FORMED IN MATERIAL WEATHERED FROM IMPURE LIMESTONE. TYPICALLY THESE SOILS HAVE A DARK GRAYISH BROWN SILT LOAM SURFACE LAYER 10 INCHES THICK. THE SUBSOIL FROM 10 TO 53 INCHES IS YELLOWISH-BROWN AND BROWNISHYELLOW SILTY CLAY LOAM. THE SUBSTRATUM FROM 53 TO 60 INCHES IS YELLOWISH-BROWN SHALY SILT LOAM. SLOPE RANGE FROM 0 TO 35 PERCENT. Map DsC - Duffield silt loam, 8 to 15 percent slopes Description Category: SO5 THE DUFFIELD SERIES CONSISTS OF VERY DEEP AND DEEP, WELL DRAINED SOILS ON UPLANDS. THEY FORMED IN MATERIAL WEATHERED FROM IMPURE LIMESTONE. TYPICALLY THESE SOILS HAVE A DARK GRAYISH BROWN SILT LOAM SURFACE LAYER 10 INCHES THICK. THE SUBSOIL FROM 10 TO 53 INCHES IS YELLOWISH-BROWN AND BROWNISHYELLOW SILTY CLAY LOAM. THE SUBSTRATUM FROM 53 TO 60 INCHES IS YELLOWISH-BROWN SHALY SILT LOAM. SLOPE RANGE FROM 0 TO 35 PERCENT Map HaB - Hagerstown silt loam, 3 to 8 percent slopes Description Category: SO5 THE HAGERSTOWN SERIES CONSISTS OF VERY DEEP, WELLDRAINED, REDDISH SOILS ON UPLANDS. THEY FORMED IN MATERIALS WEATHERED FROM HARD LIMESTONE. TYPICALLY THESE SOILS HAVE AN 8 INCH PLOW LAYER OF BROWN OR DARK BROWN SILT LOAM. THE MATERIAL BELOW THIS DEPTH AND EXTENDING RATHER UNIFORMLY TO BEDROCK IS GENERALLY YELLOWISH RED CLAY OR SILTY CLAY, WITH LIMESTONE FRAGMENTS COMMON IN THE LOWER SUBSOIL AND SUBSTRATUM. SINK HOLES OCCUR IN SOME PLACES. LIMESTONE ROCK OUTCROPS ARE VERY COMMON BUT SOIL CAN USUALLY BE FARMED BETWEEN OUTCROPS. SLOPES RANGE FROM 0 TO 60 PERCENT. Map HbC - Hagerstown silty clay loam, 8 to 15 percent slopes, very rocky Description Category: SO5 THE HAGERSTOWN SERIES CONSISTS OF VERY DEEP, WELLDRAINED, REDDISH SOILS ON UPLANDS. THEY FORMED IN MATERIALS WEATHERED FROM HARD LIMESTONE. TYPICALLY THESE SOILS HAVE AN 2 8 INCH PLOW LAYER OF BROWN OR DARK BROWN SILT LOAM. THE MATERIAL BELOW THIS DEPTH AND EXTENDING RATHER UNIFORMLY TO BEDROCK IS GENERALLY YELLOWISH RED CLAY OR SILTY CLAY, WITH LIMESTONE FRAGMENTS COMMON IN THE LOWER SUBSOIL AND SUBSTRATUM. SINK HOLES OCCUR IN SOME PLACES. LIMESTONE ROCK OUTCROPS ARE VERY COMMON BUT SOIL CAN USUALLY BE FARMED BETWEEN OUTCROPS. SLOPES RANGE FROM 0 TO 60 PERCENT. Map RmB - Ryder-Duffield channery silt loams, 3 to 8 percent slopes Description Category: SO5 THE RYDER SERIES CONSISTS OF MODERATELY DEEP, WELLDRAINED SOILS ON UPLANDS. THEY FORMED IN MATERIAL WEATHERED FROM SHALY LIMESTONE. TYPICALLY, THESE SOILS HAVE A YELLOWISH BROWN SILT LOAM SURFACE LAYER 8 INCHES THICK. THE SUFSOIL FORM 8 TO 30 INCHES IS YELLOWISH-BROWN FRIABLE SILT LOAM IN THE UPPER PART AND LIGHT YELLOWISH-FROWN FIRM CHANNERY SILTY CLAY LOAM IN THE LOWER PART. THE SUBSTRATUM FROM 30 TO 35 INCHES IS YELLOWISH-BROWN AND BROWN VERY CHANNERY SILT LOAM. SHALY LIMESTONE IS AT 35 INCHES THE DUFFIELD SERIES CONSISTS OF VERY DEEP AND DEEP, WELL DRAINED SOILS ON UPLANDS. THEY FORMED IN MATERIAL WEATHERED FROM IMPURE LIMESTONE. TYPICALLY THESE SOILS HAVE A DARK GRAYISH BROWN SILT LOAM SURFACE LAYER 10 INCHES THICK. THE SUBSOIL FROM 10 TO 53 INCHES IS YELLOWISH-BROWN AND BROWNISHYELLOW SILTY CLAY LOAM. THE SUBSTRATUM FROM 53 TO 60 INCHES IS YELLOWISH-BROWN SHALY SILTLOAM. LIMESTONE OUTCROPS ARE VERY COMMON. SLOPES RANGE FROM 0 TO 45 PERCENT. Map RmC - Ryder-Duffield channery silt loams, 8 to 15 percent slopes Description Category: SO5 THE RYDER SERIES CONSISTS OF MODERATELY DEEP, WELLDRAINED SOILS ON UPLANDS. THEY FORMED IN MATERIAL WEATHERED FROM SHALY LIMESTONE. TYPICALLY, THESE SOILS HAVE A YELLOWISH BROWN SILT LOAM SURFACE LAYER 8 INCHES THICK. THE SUFSOIL FORM 8 TO 30 INCHES IS YELLOWISH-BROWN FRIABLE SILT LOAM IN THE UPPER PART AND LIGHT YELLOWISH-FROWN FIRM CHANNERY SILTY CLAY LOAM IN THE LOWER PART. THE SUBSTRATUM FROM 30 TO 35 INCHES IS YELLOWISH-BROWN AND BROWN VERY CHANNERY SILT LOAM. SHALY LIMESTONE IS AT 35 INCHES THE DUFFIELD SERIES CONSISTS OF VERY DEEP AND DEEP, WELL DRAINED SOILS ON UPLANDS. THEY FORMED IN MATERIAL WEATHERED FROM IMPURE LIMESTONE. TYPICALLY THESE SOILS HAVE A DARK GRAYISH BROWN SILT LOAM SURFACE LAYER 10 INCHES THICK. THE SUBSOIL FROM 10 TO 53 INCHES IS YELLOWISH-BROWN AND BROWNISH3 YELLOW SILTY CLAY LOAM. THE SUBSTRATUM FROM 53 TO 60 INCHES IS YELLOWISH-BROWN SHALY SILT LOAM. LIMESTONE OUTCROPS ARE VERY COMMON. SLOPES RANGE FROM 0 TO 45 PERCENT. Map RnC - Ryder-Nollville channery silt loams, 8 to 15 percent slopes Description Category: SO5 THE RYDER SERIES CONSISTS OF MODERATELY DEEP, WELLDRAINED SOILS ON UPLANDS. THEY FORMED IN MATERIAL WEATHERED FROM SHALY LIMESTONE. TYPICALLY, THESE SOILS HAVE A YELLOWISH BROWN SILT LOAM SURFACE LAYER 8 INCHES THICK. THE SUFSOIL FORM 8 TO 30 INCHES IS YELLOWISH-BROWN FRIABLE SILT LOAM IN THE UPPER PART AND LIGHT YELLOWISH-FROWN FIRM CHANNERY SILTY CLAY LOAM IN THE LOWER PART. THE SUBSTRATUM FROM 30 TO 35 INCHES IS YELLOWISH-BROWN AND BROWN VERY CHANNERY SILT LOAM. SHALY LIMESTONE IS AT 35 INCHES. THE NOLLVILLE SERIES CONSISTS OF DEEP, WELL DRAINED SOILS ON UPLANDS. THEY FORMED IN RESIDUAL MATERIALS DERIVED FROM ARGILLACEOUS LIMESTONE AND LIMY SHALE NOLLVILLE SOILS ARE ON CONVEX UPLAND RIDGES OF LOW RELIEF. TYPICALLY THESE SOILS HAVE A DARK YELLOWISH BROWN CHANNERY SILT LOAM SURFACE LAYER 10 INCHES THICK. THE SUBSOIL FROM 10 TO 29 INCHES IS YELLOWISH BROWN SILTY CLAY LOAM OR ITS CHANNERY ANALOGUE, AND FROM 29 TO 41 INCHES IS STRONG BROWN SILTY CLAY. THE SUBSTRATUM FROM 41 TO 57 INCHES IS STRONG BROWN VERY CHANNERY SILTY CLAY LOAM. SLOPES RANGE FROM 3 TO 35 PERCENT. Map SpA - Swanpond silt loam, 0 to 3 percent slopes Description Category: SO5 THE SWANPOND SERIES CONSISTS OF VERY DEEP, MODERATELY WELL DRAINED, SLOWLY PERMEABLE SOILS. THEY FORMED IN RESIDUUM WEATHERED FROM CALCAREOUS SHALE AND LIMESTONE ROCK, ON BROAD FLAT SUMMITS, BACKSLOPES, DEPRESSIONS, AND UPLAND DRAINAGE SWALES. TYPICALLY THESE SOILS HAVE A BROWN SURFACE LAYER 12 INCHES THICK. THE SUBSOIL FROM 12 TO 70 INCHES IS A YELLOWISH BROWN CLAY. THE SUBSOILS FROM 70 TO 73 INCHES IS A BROWNISH YELLOW SILTY CLAY. SLOPES RANGE FROM 0 TO 8 PERCENT. Map SsA - Swanpond-Funkstown silt loams, 0 to 3 percent slopes Description Category: SO5 THE SWANPOND SERIES CONSISTS OF VERY DEEP, MODERATELY WELL DRAINED, SLOWLY PERMEABLE SOILS. THEY FORMED IN RESIDUUM WEATHERED FROM CALCAREOUS SHALE AND LIMESTONE ROCK, ON BROAD FLAT SUMMITS, BACKSLOPES, DEPRESSIONS, AND UPLAND DRAINAGE SWALES. TYPICALLY THESE SOILS HAVE A BROWN 4 SURFACE LAYER 12 INCHES THICK. THE SUBSOIL FROM 12 TO 70 INCHES IS A YELLOWISH BROWN CLAY. THE SUBSOILS FROM 70 TO 73 INCHES IS A BROWNISH YELLOW SILTY CLAY. SLOPES RANGE FROM 0 TO 8 PERCENT. THE FUNKSTOWN SERIES CONSISTS OF VERY DEEP, MODERATELY WELL DRAINED, MODERATELY PERMEABLE SOILS ON UPLAND DRAINAGEWAYS AND HEAD SLOPES. THEY FORMED FROM LOCAL ALLUVIAL AND COLLUVIAL MATERIALS OVERLYING LIMESTONE RESIDIUUM. TYPICALLY THE SURFACE IS YELLOWISH BROWN SILT LOAM FROM 0 TO 12 INCHES, FOLLOWED BY STRONG BROWN GRAVELLY SILT LOAM FROM 12 TO 22 INCHES. THE UPPER SUBSOIL IS STRONG BROWN VERY GRAVELLY SILT LOAM FROM 22 TO 30 INCHES. THE LOWER SUBSOIL AND SUBSTRATUM IS YELLOWISH BROWN OR YELLOWISH RED SILTY CLAY LOAM, CLAY LOAM OR SILT LOAM. SLOPE RANGES FROM 0 TO 3 PERCENT. 5 This section of the manual includes material from the NRCS publications From the Surface Down and Field Book for Describing and Sampling Soils, the University of Maryland publication A Guide to Landjudging in Maryland and the GLOBE program’s publication GLOBE 2002 Teachers Guide - Soils Chapter. For more information, citations and websites for these publications are listed at the end of this section. Overview Soils are a thin layer on top of most of the earth’s land surface. This thin layer is a basic natural resource. Soils deeply affect every other part of the ecosystem. They are used by humans to meet many needs. Soils hold nutrients and water for plants and animals. Water is filtered and cleansed as it flows through soils. Soils affect the chemistry of water and the amount of water that returns to the atmosphere to form rain. The food we eat and most of the material we use for paper, buildings and clothing are dependent on soils. Much of our life's activities and pursuits are related and influenced by the behavior of the soil around our houses, roads, septic and sewage disposal systems, airports, parks, recreation sites, farms, forests, schools, and shopping centers. What is put on the land should be guided by the soil that is beneath it. Land is a natural resource as are water and mineral deposits. It is essentially fixed; more land cannot be made, except what little might be reclaimed from the sea or filled into water bodies. Much land and its associated soil resources have been misused. Many acres misused to the point where reclamation is nearly impossible or impractical. As our population increases and the pressure for land intensifies, it is important that the wisest use be made of this resource. We can no longer afford to mismanage land and soil. 6 SOIL COMPOSITION Soils are composed of three main ingredients: minerals of different sizes; organic materials from the remains of dead plants and animals; and open space that can be filled with water or air. A good soil for growing most plants should have about 45% mineral (with a mixture of sand, silt and clay), 5% organic matter, 25% air, and 25% water (fig. 1). Soils are dynamic and change over time. Some properties, such as temperature and water content change very quickly. Others, such as mineral transformations, occur very slowly over hundreds or thousands of years. Soil Composition Water 25% Mineral 45% Air 25% Organic Matter 5% Figure 1. The relative proportion of mineral, organic matter, air and water in a soil that is optimum for growing plants. 7 FACTORS OF SOIL FORMATION Soils are natural expressions of the environment in which they were formed. They are derived from an infinite variety of materials that have been subjected to a wide spectrum of climatic conditions. Soil development is influenced by the topography on which soils occur, the plant and animal life which they support and the amount of time which they have been exposed to these conditions. Soi1 scientists recognize five major factors that influence soil formation: 1) parent material, 2) climate, 3) living organisms (especially native vegetation), 4) topography and 5) time. The combined influence of these soil-forming factors determines the properties of a soil and their degree of expression (fig. 2). Figure 2. The five factors of soil formation affect the processes that influence soil development. Parent Material Parent material refers to organic (such as fresh peat) and mineral material in which soil formation begins. Mineral material includes partially weathered rock, ash from volcanos, 8 sediments moved and deposited by wind and water, or ground up rock deposited by glaciers. The material has a strong effect on the type of soil developed as well as the rate at which development takes place. Soil development may take place quicker in materials that are more permeable to water. Dense, massive, clayey materials can be resistant to soil formation processes. Bedrock such as limestone, sandstone, shale, granite, gneiss and schist, slate, marble and many others break down into residuum (residue) through the weathering process. It is this residuum that becomes the parent material of soil and imparts some of the parent characteristics into the resulting soil profile. Soil material and rock fragments may fall, roll or slide downslope under the influence of gravity and water. This incoherent mass of material that generally accumulates on the lower portion of slopes and in depressions is called colluvium. Rock fragments in colluvium generally are angular in contrast to the rounded waterworn cobbles and stones found in alluvium and glacial outwash. Streams and rivers commonly overflow their banks and deposit fresh materials on the floodplains. These fresh or recent deposits, commonly topsoil, comprise the parent materials for the soils developed on these floodplains. Since there is new material added almost annually, the soils never have time to form well-developed horizons. Therefore, these young soils have poorly developed profiles, and most of their character is inherited from the parent material. This type of parent material exceeds 0.5 m (20 in.) in depth, and it is referred to on the scorecard as recent alluvium. Soils located on stream terrace positions that contain water worn coarse fragments have parent materials referred to as old alluvium. These soils were originally deposited by water and commonly have had time to form well-developed horizons. They never or rarely flood, and thus are not influenced by deposition of fresh materials. 9 In the Mid-Atlantic region, large areas are underlain by the complex series of waterdeposited sediments left by previous geologic events. These older sediments comprise the Coastal Plain along the Atlantic seaboard. In Maryland, these materials occupy half of the land area, and they comprise nearly all the parent material for Delaware soils and large segments of New Jersey. These Coastal Plain sediments, although much older than the recent alluvium along streams, have not been cemented and consolidated into bedrock-thus, the name unconsolidated sediments. Often these sediments have been capped or coated with a thin (several cm to several m) veneer or sheet of material consisting mainly of silt (loess). The wind may have carried this material from the glacial outwash areas before the rise in sea level that formed the Chesapeake Bay. The Coastal Plain soils are formed in these sediments and silt-cap parent materials. Therefore, soils occurring on the upland portions of the Coastal Plain are considered to have Coastal Plain sediments as their parent materials on the scorecard. Recent alluvium can and does occur on the Coastal Plain in the same landscape positions (along streams and rivers) as in other sections of the state. Climate Climate is a major factor in determining the kind of plant and animal life on and in the soil. It determines the amount of water available for weathering minerals, transporting the minerals and releasing elements. Climate, through its influence on soil temperature, determines the rate of chemical weathering. Warm, moist climates encourage rapid plant growth and thus high organic matter production. The opposite is true for cold, dry climates. Organic matter decomposition is also accelerated in warm, moist climates. Under the control of climate freezing, thawing, wetting, and drying break parent material apart. Rainfall causes leaching. Rain dissolves some minerals, such as carbonates, and transports them deeper into the soil. Some acid soils have developed from parent 10 materials that originally contained limestone. Rainfall can also be acid, especially downwind from industrial processes. Living organisms Plants affect soil development by supplying upper layers with organic matter, recycling nutrients from lower to upper layers, and helping to prevent erosion. In general, deep rooted plants contribute more to soil development than shallow rooted plants because the passages they create allow greater water movement, which in turn aids in leaching. Leaves, twigs, and bark from large plants fall onto the soil and are broken down by fungi, bacteria, insects, earthworms, and burrowing animals. These organisms eat and break down organic matter releasing plant nutrients. Some change certain elements, such as sulfur and nitrogen, into usable forms for plants. Microscopic organisms and the humus they produce act as a kind of glue to hold soil particles together in aggregates. Well-aggregated soil is ideal for providing the right combination of air and water to plant roots. Animals living in the soil affect decomposition of waste materials and how soil materials will be moved around in the soil profile. Landscape position Landscape position causes localized changes in moisture and temperature. When rain falls on a landscape, water begins to move downward by the force of gravity, either through the soil or across the surface to a lower elevation. Even though the landscape has the same soil-forming factors of climate, organisms, parent material, and time, drier soils at higher elevations may be quite different from the wetter soils where water accumulates. Wetter areas may have reducing conditions that will inhibit proper root growth for plants that require a balance of soil oxygen, water, and nutrients. 11 Steepness, shape, and length of slope are important because they influence the rate at which water flows into or off the soil. If unprotected, soils on slopes may erode leaving a thinner surface layer. Eroded soils tend to be less fertile and have less available water than uneroded soils of the same series. Aspect affects soil temperature. Generally, for most of the continental United States, soils on north-facing slopes tend to be cooler and wetter than soils on south-facing slopes. Soils on north-facing slopes tend to have thicker A and B horizons and tend to be less droughty. Position Position generally refers to the point on the landscape where the soil is located. Most soil series have a rather limited range of position and land form. In figure 3, the landscape is divided into (1) upland, (2) upland depression, (3) terrace, and (4) floodplain. Most soils can be classified into one of these landscape positions by observing the general surroundings in respect to streams or natural drainage systems. Figure 3. Landscape position can be upland, upland depression, terrace, or floodplain. 12 The floodplains refer to areas near streams that flood periodically. These soils may be quite productive, but they have a flooding hazard that seriously limits their use for urban development or agriculture. Terrace refers to soils developed in older alluvial materials above the zone of current flooding. Upland depressions or waterways refer to soils developed on concave land forms or at the heads of drainage ways and along waterways where surface drainage is retarded. Water tends to pond in these depressions, and the soils commonly have a darker and thicker surface horizon because of organic matter accumulations. Areas unaffected by stream activity in recent geologic time, and ordinarily lying at higher elevations (than alluvial plains) on rolling and convex positions, are designated upland. Slope Characteristics Slope generally is expressed as a percentage that is calculated by dividing the difference in elevation between two points by the horizontal distance and multiplying by 100. For example, a 10 percent slope would have a 10-foot drop per 100 horizontal feet. The percent slope can be estimated visually, but the Abney level, or a similar type of instrument, is used for more precise measurements. Slope classes are used for interpretive purposes. The classes are nearly level, gently sloping, strongly sloping, moderately steep, steep and very steep. The range in percentages for these classes will vary depending on the topography of the area. Because of contrasting landscapes, two divisions are used in establishing limits for the slope classes in Maryland: (1) the Coastal Plain and (2) a combination formed by the Appalachian and Piedmont provinces. The slope classes and appropriate ranges of percent for the two divisions are shown in table 1. 13 Table 1. Slope classes for Maryland’s Coastal Plain and Piedmont-Appalachian provinces and their corresponding letter designations in the soil survey. Slope Class Coastal Plain Piedmont-Appalachian Soil Survey Percentage Percentage Letter Designation Nearly level 0-2 0-3 A Gently sloping 2-5 3-8 B Strongly sloping 5-10 8-15 C Moderately steep 10-15 15 25 D Steep 15-25 25-50 E Very steep 25+ 50+ F Time Time is required for horizon formation. The longer a soil surface has been exposed to soil forming agents like rain and growing plants, the greater the development of the soil profile. Soils in recent alluvial or windblown materials or soils on steep slopes where erosion has been active may show very little horizon development. Soils on older, stable surfaces generally have well defined horizons because the rate of soil formation has exceeded the rate of geologic erosion or deposition. As soils age, many original minerals are destroyed and many new ones are formed. Soils become more leached, more acid, and more clayey. In many well drained soils, the B horizons tend to become redder with time. SOIL FORMING PROCESSES The four major processes that change parent material into soil are additions, losses, translocations, and transformations. 14 Additions The most obvious addition is organic matter. As soon as plant life begins to grow in fresh parent material, organic matter begins to accumulate. Organic matter gives a black or dark brown color to surface layer. Most organic matter additions to the surface increase the cation exchange capacity and nutrients, which also increase plant nutrient availability. Other additions may come with rainfall or deposition by wind, such as the wind blown or eolian material. On the average, rainfall adds about 5 pounds of nitrogen per acre per year. By causing rivers to flood, rainfall is indirectly responsible for the addition of new sediment to the soil on a flood plain. Losses Most losses occur by leaching. Water moving through the soil dissolves certain minerals and transports them into deeper layers. Some materials, especially sodium salts, gypsum, and calcium carbonate, are relatively soluble. They are removed early in the soil's formation. As a result, soil in humid regions generally does not have carbonates in the upper horizons. Quartz, aluminum, iron oxide, and kaolinitic clay weather slowly. They remain in the soil and become the main components of highly weathered soil. Fertilizers are relatively soluble, and many, such as nitrogen and potassium, are readily lost by leaching, either by natural rainfall or by irrigation water. Long- term use of fertilizers based on ammonium may cause acidity in the soil and contribute to the loss of carbonates in some areas. Oxygen, a gas, is released into the atmosphere by growing plants. Carbon dioxide is consumed by growing plants, but lost to the soil as fresh organic matter decays. When soil is wet, nitrogen can be changed to a gas and lost to the atmosphere. 15 Solid mineral and organic particles are lost by erosion. Such losses can be serious because the material lost is usually the most productive part of the soil profile. On the other hand, the sediment relocated to lower slope positions or deposited on bottom lands has the potential to increase or decrease productive use of soils in those areas. Translocations Translocation means movement from one place to another. In low rainfall areas, leaching often is incomplete. Water starts moving down through the soil, dissolving soluble minerals as it goes. There isn't enough water, however, to move all the way through the soil. When the water stops moving, then evaporates, salts are left behind. Soil layers with calcium carbonate or other salt accumulations form this way. If this cycle occurs enough times, a calcareous hardpan can form. Translocation upward and lateral movement is also possible. Even in dry areas, low-lying soils can have a high water table. Evaporation at the surface causes water to move upward. Salts that are dissolved in solution will move upward with the water and deposit on the surface as the water evaporates. Transformations Transformations are changes that take place in the soil. Microorganisms that live in the soil feed on fresh organic matter and change it into humus. Chemical weathering changes parent material. Some minerals are destroyed completely. Others are changed into new minerals. Many of the clay-sized particles in soil are actually new minerals that form during soil development. Other transformations can change the form of certain materials. Iron oxides (ferric form) usually give soils a yellowish or reddish color. In waterlogged soils, however, iron oxides lose some of their oxygen and are referred to as being reduced. The reduced form of iron 16 (ferrous) is quite easily removed from the soil by leaching. After the iron is gone, generally the leached area has a grayish or whitish color. Repeated cycles of saturation and drying create a mottled soil (splotches of colored soil in a matrix of different color). Part of the soil is gray because of the loss of iron, and part is a browner color where the iron oxide is not removed. During long periods of saturation, gray lined root channels develop. This may indicate a possible loss of iron or an addition of humus from decayed roots. 17 SOIL FEATURES There are many properties or features that describe and characterize soils (fig. 4). Some of these features (such as color, texture and depth) are relatively easy to record while others require very sophisticated equipment and highly technical procedures (such as chemical data and mineralogical analysis). Climate Slope Erosion Overflow Vegetation SOIL Physical Properties Water Supplying Capacity Chemical Properties Nutrient Supplying Capacity Wetness Texture Figure 4. Soil properties that can influence use and management of land. The Soil Profile Due to the interactions of the five soil-forming factors, soils differ greatly. Each section of soil on a landscape has its own unique characteristics. The way a soil looks if you cut a section of it out of the ground is called a soil profile. When you learn to interpret it, the profile can tell you about the geology and climate history of the landscape over thousands of years, the archeological history of how humans used the soil, what the soil properties are used today, and the best way to use the soil. In a sense, each soil profile tells a story about the location where it was found. 18 Soil horizons Soils are deposited in or developed into layers. These layers, called horizons, can be seen where roads have been cut through hills, where streams have scoured through valleys, or in other areas where the soil is exposed. Surface Subsoil Substratum Figure 5. Soil profile separated into horizons. Where soil forming factors are favorable, five or six master horizons may be in a mineral soil profile (fig. 5). Each master horizon is subdivided into specific layers that have a unique identity. The thickness of each layer varies with location. Under disturbed conditions, such as intensive agriculture, or where erosion is severe, not all horizons will be present. The uppermost layer generally is an organic horizon, or O horizon. It consists of fresh and decaying plant residue from such sources as leaves, needles, twigs, moss, lichens, and other organic material accumulations. Some organic materials were deposited under water (fig. 6). Subdivisions of Oa, Oe, and Oi are used to identify levels of decomposition. The O horizon is dark because decomposition is producing humus. 19 Oi horizon Figure 6. Profile on the left shows an Oi horizon at the surface; an organic horizon with little decomposition. Profile to the right shows an Oa horizon; an organic horizon that is highly decomposed. A horizon Ap horizon Ab horizon Figure 7. The soil profile to the right shows a well drained soil with an A horizon from the surface to a depth of 5 cm (2 in.). The measuring tape is in feet. The middle soil profile is a somewhat poorly drained soil with the top of the gray due to wetness occurring at 40 cm (16 in.). Tape measure is in meters. The middle soil profile has a buried A horizon starting at 1 m (40 in.). The soil profile to the left is moderately well drained with an Ap horizon from the surface to 20 cm (8 in.). 20 Below the O horizon is the A horizon. The A horizon is mainly mineral material. It is generally darker than the lower horizons because of the varying amounts of humified organic matter (fig. 7). It is the horizon of maximum biological activity. This horizon is where most root activity occurs and is usually the most productive layer of soil. It may be referred to as a surface layer in a soil survey. An A horizon that has been buried beneath more recent deposits is designated as an "Ab" horizon (fig. 7). An A horizon that has been plowed or otherwise manipulated is an Ap horizon (fig. 7). The E horizon generally is bleached or whitish in appearance (fig. 8). As water moves down through this horizon, soluble minerals and nutrients dissolve and some dissolved materials are washed (leached) out. The main feature of this horizon is the loss of silicate clay, iron, aluminum, humus, or some combination of these, leaving a concentration of sand and silt particles. E horizon B horizon C horizon Figure 8. This profile is a soil found in the Appalachian Plateau showing an E horizon from 20 to 35 cm (8 to 14 in.) and a B horizon from 35 to 55 cm (14 to 22 in.) Measuring tape is in 10 cm increments. Below 55 cm (22 in.) is a C horizon. 21 Below the A or E horizon is the B horizon, or subsoil (fig. 8). The B horizon is usually lighter colored, denser, and lower in organic matter than the A horizon. It commonly is the zone where leached materials accumulate. The B horizon is further defined by the materials that make up the accumulation, such as "t" in the form of "Bt", which identifies that clay has accumulated. Other illuvial concentrations or accumulations include iron, aluminum, humus, carbonates, gypsum, or silica. Soil not having recognizable concentrations within B horizons but show color or structural differences from adjacent horizons is designated "Bw". Still deeper is the C horizon or substratum (fig. 8). The C horizon may consist of less clay, or other less weathered sediments. Partially disintegrated parent material and mineral particles are in this horizon. Some soils have a soft bedrock horizon that is given the designation Cr. C horizons described as "2C" consist of different material, usually of an older age than horizons which overlie it. The lowest horizon, the R horizon, is bedrock (fig. 9). Bedrock can be within a few centimeters of the surface or many meters below the surface. Where bedrock is very deep and below normal depths of observation, an R horizon is not described. R horizon Figure 9. This soil profile has 110 cm (44 in.) of unconsolidated soil material over hard bedrock. 22 Generally, soil horizons are found in the order presented (fig. 10). However, a soil profile may lack certain horizons or have horizons out of order due to factors that influenced that soil’s development. For example, a soil profile may lack E and B horizons if it is a young soil that has not had the time for an E and B horizon to develop. Or, a soil may have a buried A horizon if that soil has had material deposited on top of what was once the soil surface (fig. 7). This may occur on flood plains after a flooding event deposits sediments, because of erosion deposition, or because man has deposited material on top of the soil. Cultivated Soil O horizon – Organic material in. 0 A horizon – Mineral material E horizon – Horizon of (leaching) high in organic matter Ap maximum eluviation 10 EB or BE horizon – to B horizon transitional horizon from E 20 B horizon – zone of illuviation soil development (accumulation), maximum 30 BC or CB horizon – to C horizon transitional horizon from B 40 C Horizon – unconsolidated weathering Undisturbed Forested Soil mineral horizon with little 50 R horizon – hard bedrock 60 Figure 10. Common horizons designations and the order in which they are most commonly found. Color To the casual observer, color is the most noticeable soil property. Maryland soils vary in color from red, yellow and brown to gray in the subsoil (B horizon) and from black to very light gray in the topsoil (A horizon). Color is a significant indicator of several soil properties, including the organic matter content and drainage condition. The three components that have the most affect on soil color are organic compounds (usually black or dark brown), iron oxides (usually red, orange or yellow) and the color of the mineral grains (usually gray). 23 Black or very dark colors in the A horizon suggest relatively high organic matter contents. Most cultivated Maryland soils have organic matter in their plow layer ranging between 1 and 4 percent by weight. In some poorly drained soils, the organic matter content will reach 10 percent and higher. Generally, the darker the A horizon the higher the organic matter content. In Maryland, this generalization can be taken a step further; a deep, dark colored A horizon indicates the soil was formed under very poorly drained conditions. Organic matter enhances soil tilth (physical condition) or structure and is a natural nitrogen supplier under favorable conditions. As the organic matter content decreases, the color is determined more by the mineral components of the horizon. Pale colors indicate that the horizon has low organic matter content (fig. 11). Figure 11. The soil profile on the left has a dark surface high in organic matter, while the soil profile on the right has a pale surface low in organic matter. The measuring tapes are in meters. 24 Subsoil colors are not greatly influenced by organic matter. Usually, the iron compounds coating the mineral particles are largely responsible for the color of this horizon. Soils formed under well-drained conditions, where oxygen is readily available, have subsoils with bright colors, usually brown, red or yellow (iron oxide colors). Some grayish tones may occur in these soils, but they are associated with the weathering of rocks and not drainage. Usually, soils formed under well-drained conditions are uniform in color, however, mottles (splotches of color), may occur due to weathering of rock fragments or parent material colors, etc (fig. 12). Brown, red or yellow colors can be interpreted as indicating good natural drainage making artificial drainage unnecessary. Septic systems should work in these soils unless they contain too much clay. Also, these soils should provide good dry locations for houses with basements. Figure 12. The red and gray colors in this soil profile are inherited from its parent material. 25 When these bright colors are mixed with areas of gray (color of the mineral grains) the soil developed under conditions of imperfect drainage. The mixed pattern, called redoximorphic features, indicates that the soil is saturated with water for significant periods during the year (fig. 13). This pattern is caused when iron is reduced due to wetness and moved leaving splotches where of gray colors where the mineral grains have been stripped of iron. Artificial drainage usually is necessary for good crop production and septic systems are subject to periodic failure when installed in these soils. Figure 13. The red and gray colors in these soil profiles are due to wetness. These splotches of colors due to wetness are called redoximorphic features. The soil profiled and the left has a predominance of gray due to the loss of iron starting close to the bottom of the spade. The soil on the right has a predominance of red with gray splotches starting at 1 m (40 in.). The measuring tape for the profile on the right is in meters. When gray (color of the mineral grains) predominates with only streaks and spots of brighter colors (redoximorphic features) the soil was formed under poorly drained conditions. The spots of brighter colors are where the iron has re-oxidized forming spots 26 similar to rust. These soils are called hydric soils, soil that have a water table near the surface for significant periods of time. Artificial drainage is necessary for crop production, and these soils are poor building sites, especially where septic systems are needed. Figure 14. This soil profile is a hydric soil. The predominance of gray colors with splotches of red near the soil surface demonstrates the typical pattern of redoximorphic features found in a hydric soil. When determining colors, make sure that the soil is moist. Moistened soil better illustrates color variations, making it easier to distinguish one horizon from another. Soil scientists use standard color (Munsell) charts to determine color (fig. 15); this permits uniformity and eliminates some of the human variable. According to the chart, a soil horizon described as yellowish-brown in Maryland has exactly the same color as a yellowish-brown horizon in California. 27 Figure 15. The Munsell soil color book is used to standardize soil color designations. Organic vs. mineral soil material Organic soil contains high amounts of organic matter. Organic soil material will be very dark in color, contain fibers, and will feel greasy when rubbed. Organic soil material is usually found at the soil surface, where leaves, twigs, and other sources of organics accumulate. When observing organic soil material, you may be able to readily identify leaves and twigs and other sources of organics. This is relatively undecomposed and is considered to be peat. If the source of organics is not easily identified the organic matter is more highly decomposed and would be considered mucky-peat (intermediate decomposition) or muck (high decomposition). Mineral soil texture (USDA) Texture is determined by the relative proportion of sand, silt, and clay (mineral material 2 to 75 mm diameter (0.08 to 3 in.) – Cobbles >75 to 250 mm diameter (3 to 10 in.) – Stones >250 to 600 mm diameter (10 to 25 in.) – Boulders >600 mm diameter (>25 in.) Flat – Channers >2 to 150 mm long (0.08 to 6 in.) – Flagstones >150 to 380 mm long (6 to 15.2 in.) – Stones >380 to 600 mm long (15.2 to 25 in.) – Boulders >600 mm long (>25 in.) Figure 19. This soil profile contains cobble size rock fragments in a high enough concentration to put an extremely cobbly modifier on the texture. 32 If a soil horizon contains more than 15 percent rock fragments a modifier is put on the texture (fig. 19). For example if a soil horizon contains 20 percent gravel size rock fragments and the texture is a sandy loam, the modifier would be gravelly and the texture would be labeled gravelly sandy loam. Table 2 shows modifiers used when the gravel content is greater than 15 percent. Table 2. Rock fragment texture modifiers. Fragment Content % by Rock Fragment Modifier Volume 4 and chroma > 4 8. Pin Flag – Compaction – the amount of compaction of the topsoil layer is related to soil health and root growth. The more compaction the worst the health of the soil is. Insertion of a pin flag, into the topsoil, can infer the amount of compaction. Good: Wire flag enters soil easily to a depth below the topsoil layer; unrestricted root penetration. Fair: Wire flag enters soil, but requires force to reach a depth below the topsoil layer; root growth restricted. Poor: Wire flag enters soil with force, but does not penetrate through the topsoil layer; roots growing laterally. 9. Structure and Aggregation of Topsoil – the amount of aggregation/structure of the topsoil layer is related to soil health. The more aggregation and fine roots in the layer the better the soil health. Good: Soil is granular, soft and crumbly, held together with many fine roots. Looks like cottage cheese. Fair: Soil is blocky and firmer with some fine roots. Poor: Soil is single grain, massive or platy and hard to break apart. It has few or no fine roots. 10. Nutrient Management (page 64) - requires basic knowledge of types of crops (legumes vs. non legumes), soil test results, and when nutrients as well as lime should be applied. Legume crops such as soybeans, alfalfa, and clovers do not require nitrogen. All other crops such as corn, small grains, and grasses for hay or pasture require supplemental nitrogen for optimum productivity. Recommendations are given for the crop indicated on information sign irrespective of what might actually be growing on the site. Soil tests for magnesium, phosphorus, and potassium will be given on information sign as VL = Very low, L = Low, M = Medium, H = High or VH = Very high. These nutrients are needed or recommended if the soil test is VL, L or M. Lime is recommended if the pH of the topsoil layer is less than 6.5. Lime: check if pH 72 inches, depth to redox depletions (gray colors/wetness) in the 40 72 inch range and slow permeability, the suitability would be SEVERE because of the slow permeability. Caution - since many soil pits, for safety purposes are seldom excavated to a depth of 72 inches or more, it is presumed that conditions evident at the bottom of the exposed profile, i.e. at 60 inches for example, also represent conditions at > 72 inches unless specific guidance to the contrary is provided on the information sign or by the proctor. 78 12. Suitability for Lawns - is similar in format to suitability for septic tank absorption fields except that key soil properties are different as are some criteria depth ranges, i.e. depth to redox depletions (wetness). This suitability rating also requires the estimation of % rock fragment (gravel) by volume in the surface layer. Representative samples of varying gravel contents should be carefully evaluated during training sessions for reference. Soil properties include slope, soil surface texture, rock fragments in or on surface, past erosion, and, depth to redox depletions (gray colors/wetness) 13. Suitability for Dwellings with basements - is similar in format to other suitability questions except soil features and criteria change. Again, soil features determined in earlier portion of exam are used to arrive at an overall suitability. Soil features include slope, flooding, depth to bedrock, depth to redox depletions (gray colors/wetness). Wildlife Suitability 14. Suitability for Wildlife habitat Section II. Soil Survey Use (page 53) - this portion of exam is intended to expose the participant to the soil survey report and how to find soils information contained in it. The participant will be given a real-life scenario and a soils map with a legend of the mapping units. They will be required to use the report to find the answers to questions related to the soil map. Some questions may be related to soil interpretations others to specific soil properties. In most cases the questions will be the same across the county or state but responses will change depending upon the soil survey area. An example of a scenario is: “You have just purchased a piece of property in ??????? County. The following is the soils map and soil legend for the property you just purchased. You’re unsure of what you want to do. You may want to develop it, do some farming, or change some areas to attract wildlife. Using the soil survey, answer the following questions to help you decide where the most appropriate places are to do these things on your property.” NOTE: Although the “official” soil surveys for Maryland are all on the NRCS Web Soil Survey internet site (http://websoilsurvey.nrcs.usda.gov/app/), for the contest, soil survey information reports will be provided to the students for answering questions. Section III. Fifth Issue as Related to Soils - this portion of the exam consists of general knowledge questions of the current Fifth Issue subject as it is related to soils. The questions are usually taken from reference materials posted on the State Envirothon web page or from handouts provided by the soil instructors. 79