Soils

10 Key excerpts on "Soils"

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  eBook - PDF

  The Environment

  Science, Issues, and Solutions

  • Mohan K. Wali, Fatih Evrendilek, M. Siobhan Fennessy(Authors)
  • 2009(Publication Date)
  • CRC Press

    (Publisher)

  51 Topics Soil Defined Origin of Soils Soil Physical Characteristics Soil Chemical Relations Soil Biota Soils and Plant Distribution Soil Formation Major Soils of the World 4 The Soil Environment Soil Defined Soil is the sustenance of life and water its elixir. An old saying, attributed to the Chinese, sums it all up: “Man—despite his artistic pretensions, his sophistication, and his many accomplishments— owes his existence to a six-inch layer of topsoil and the fact that it rains.” This truism is as old as human knowledge of the use of Soils. For more than 150 years and from many continents, studies have documented the interplay of geologic substrates, climate and organisms, and their interactions that produce a rich diversity of Soils that, in turn, support the mosaic of life. The definitions of Soils are numerous, but those presented in the following discussion capture both the essence and the progression in scientific thinking. Plant growth was central to the definition of Soils nearly a hundred years ago when Soils were defined as “the surface stratum of earthy material, as far as the roots of plants reach” (Hillgard 1911). It continues to be so in the latest glossary of soil science, where soil is “the unconsolidated mineral or organic material on the immediate surface of the Earth that serves as a natural medium for the growth of land plants” (Soil Science Society of America 1997). As more scientific knowledge has accumulated over the past century and a half, it has also become clear that many potentially arable Soils brought under cultivation throughout the world have been degraded by management practices. Soils have also been used as a repository for waste products that human society generates. These often exceed the capacity of Soils to assimilate such wastes, resulting in the accumulation of toxins and the pollution of ground waters and adjacent ecosystems.

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  Soils

  Genesis and Geomorphology

  • Randall J. Schaetzl, Michael L. Thompson(Authors)
  • 2015(Publication Date)
  • Cambridge University Press

    (Publisher)

  Like land-scapes, Soils evolve; changing patterns of Soils over time are a reflection of a multitude of interactions, processes, and factors, replete with feedbacks, inertia, and flows of energy and mass. Yes, Soils are a challenge! For that reason, we provide information, tools, resources, and background data to draw the reader closer to deciphering this most complicated – and important – of natural systems. Whitehead ( 1925 ) wrote, “It takes a genius to under-take the analysis of the obvious.” All people who walk the Earth’s surface depend on the soil, yet the soil is not obvi-ous to all. It is seemingly everywhere, and yet compara-tively few study it. Additionally, Soils are usually hidden from view and require excavation to be revealed. Neither are Soils discrete entities like trees, insects, or lakes, which have clearly defined outer boundaries. Instead, Soils grade continuously, one into another, until they end at the ocean, a sheer rock face, or a lake. When broken into discrete enti-ties, in the way a geologist might break apart a rock, Soils appear to lose their identity. This soil science – it’s not easy. But therein lies the challenge! We believe that a geographic approach is one of the most fruitful avenues to study Soils (Boulaine 1975 ). Like most of the components of Earth science, Soils are spatial things, varying systematically across space. To study Soils completely, we must grasp not only what they are, but also how they relate to their adjoining counterparts. Soil geog-raphy focuses upon the geographic distributions of Soils. It emphasizes their character and genesis, their interrelation-ships with the environment and humans, and their history and likely future changes. It is operationalized at many scales, from global to local. Soil geography encompasses soil genesis. Soil patterns cannot be explained without knowing the genesis of the Soils that compose that pattern.

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  Elements of the Nature and Properties of Soils

  • Gusau, W L(Authors)
  • 2018(Publication Date)
  • Agri Horti Press

    (Publisher)

  Other disciplines have their own definitions of soil –– engineers generally consider soil to be any loose material above bedrock (if it can be dug it is soil), and agronomists often consider it anything in which one can grow a plant. A tremendous variety of Soils has resulted from the wide array of parent materials, climates, and weathering environments around the world. But due to differences in soil-This ebook is exclusively for this university only. Cannot be resold/distributed. Weathering of Rocks and Minerals 207 forming processes, patterns in the distribution of soil types mirror different climate zones and geologic settings. Soils also reflect differences in landscape history, and in some cases their characteristics can be used to infer ancient climate changes, periods of landscape stability, or the nature of ancient environments. Soils are generally unconsolidated, but calcite (CaCO 3 ), silica (SiO 2 ), and iron oxide (Fe 2 O 3 ) cements that develop in some Soils add strength and allow formation of distinct erosion-resistant landforms. Factors of Soil Formation The factors that control soil development are climate, organisms (biological activity), topography (slope steepness), parent material, and time. Climate and time are the predominant factors in soil development at a regional scale, but geologic factors greatly influence local soil characteristics. Other than time, soil-forming factors are to some degree interdependent. Climate, for example, influences vegetation, and differences in parent material influence topography. Still, considering these factors independently helps to organize thinking about the things that favour soil development. Climate Climate, the long-term expression of weather, characterizes general averages and variability of temperature, humidity, wind, and precipitation.

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  Discovering Physical Geography

  • Alan F. Arbogast(Author)
  • 2017(Publication Date)
  • Wiley

    (Publisher)

  Soil science The study of soil as a natural resource through under- standing of its physical, chemical, and biological properties. Geo Media Soil Horizon Development The formation of soil horizons is complex because it involves the internal organization of sediment through a combination of addi- tions, depletions, transformations, and translocations over a period of time. This organization is best understood when it is viewed in an animated way that demonstrates the progressive development of soil. To do so, go to the Geo Media Library and select Soil Horizon Development. Once you complete the animation, be sure to answer the questions at the end to test your understanding of this concept. 246 CHAPTER 11 The Global Distribution and Character of Soils about the phenomena under study. Classification also provides a basis from which one category can be compared with another. Given the predictable pedogenic processes and factors that operate on Earth, Soils are particularly well suited for classification. Although many different classification systems are used around the world, the one used in the United States is called soil taxonomy. This system is based on the existing properties of a soil, such as color, texture, structure, and mineral content, which can be measured. Many other soil classification systems are genetic; that is, the soil scientist attempts to reconstruct how the soil evolved, even though the initial environmental conditions may not be known. Because soil taxonomy is a generic, logically based system, the classification scheme is hierarchical with several levels of general classifications, each with sublevels below it. With each successively lower level, fewer and fewer similarities appear between soil types. The highest level within soil taxonomy is the soil order. Twelve soil orders occur around the world, each one dis- tinguished on the basis of diagnostic horizons (Table 11.1) that meet certain criteria.

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  Introduction to Crop Husbandry

  (Including Grassland)

  • J. A. R. Lockhart, A. J. L. Wiseman(Authors)
  • 2014(Publication Date)
  • Pergamon

    (Publisher)

  2 Soils Soils are very complex natural formations which make up the surface of the earth. They provide a suitable environment in which plants may obtain water, nutrients and oxygen for root respiration, and firm anchorage. Soils are formed by the weathering of rocks, followed by the growth and decay of plants, animals, and soil micro-organisms. If a farmer is to provide the best possible conditions for crop growth, it is desira-ble that he should understand what Soils are, how they were formed and how they should be managed. The topsoil or surface soil is a layer about 8-45 cm deep which may be taken as the greatest depth which a farmer would plough or cultivate and in which most of the plant roots are found. Loose, cultivated, topsoil is sometimes called mould. The subsoil, which lies underneath, is an inter-mediate stage in the formation of soil from the rock below. A soil profile is a section taken through the soil down to the parent rock. In some cases this may consist of only a shallow surface soil 10-15 cm on top of a rock such as chalk or limestone. In other well-developed Soils (about a metre deep) there are usually three or more definite layers (or horizons) which vary in colour, texture and compaction (see Fig. 25). The soil profile can be examined by digging a trench or by taking out cores of soil from various depths with a soil auger. Surface vegetation Description Colour: usually greyish brown Texture: usually coarser than subsoil; very well weathered Clay, silt, humus, iron and other compounds are washed into horizon B. Colour: various shades of yellow, red or brown -may be grey or blue if waterlogged Texture; usually finer than topsoil; not fully weathered. Receives materials washed out of horizon A Rock in the early stages of weathering chemical action ■mainly due to Unweathered parent rock FIG. 25. Soil profile diagram showing the breakdown of rock to form various soil layers (horizons). 17

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  Practical and Theoretical Geoarchaeology

  • Paul Goldberg, Richard I. Macphail, Chris Carey, Yijie Zhuang(Authors)
  • 2022(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  40 Practical and Theoretical Geoarchaeology, Second Edition. Paul Goldberg and Richard I. Macphail. © 2022 John Wiley & Sons Ltd. Published 2022 by John Wiley & Sons Ltd. The soil is a natural body of animal, mineral and organic constituents differentiated into horizons of variable depth which differ from the material below in morphology, physical make-up, chemical properties and composition, and biological characteristics. (Joffe, 1949) cited by Bridges (1970) 4.1 Introduction This chapter introduces the importance of Soils in geoarchaeology, and why it is essential that Soils are clearly differentiated from natural and archaeological sediments. In order that both environ- mental and human influences on soil formation are understood, the concept of the five soil-forming factors is introduced. This provides the basis for analysis and reconstruction of past soil landscapes, and shows how soil classification and mapping are essential tools in this endeavor. Basic soil types and the horizons that make up different soil profiles are also given, and some important soil-forming processes are described. Generally, we employ generic soil names (e.g. podzol) and their Soil Survey of England and Wales equivalents (Avery, 1990), as well as international soil classification terminol- ogy from the USA and Europe, which are used worldwide (Soil Survey Staff, 2014; WRB, 2015). An understanding of Soils is fundamental to archaeology. Apart from Soils being an essential component of any environmental reconstruction and background to any human activity, they pro- vide an absolutely essential resource to humans. For example, woodland type, richness of pasture, and character of agricultural undertaking, are all governed by soil conditions. Moreover, the nature of human impact on Soils, through erosion, acidification, desertification, and management prac- tices can contribute information on the nature of contemporary human societies.

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  Introducing Physical Geography

  • Alan H. Strahler(Author)
  • 2013(Publication Date)
  • Wiley

    (Publisher)

  Burrowing animals soften, aerate, and mix soil as they burrow through the ground. Earthworms enrich the soil by digesting and excreting soil. Microorganisms help break down organic matter into humus. The Global Scope of Soils 357 A soil scientist’s rule of thumb is that it takes about 500 years to form 2.5 cm (1 in.) of topsoil. Human Activity Human activity also influences the physical and chemi- cal nature of the soil. Clearing of native vegetation for crops can induce erosion, removing upper layers that are rich in organic matter. Large areas of agricultural Soils have been plowed and planted for centuries. As a result, both the structure and composition of these agricultural Soils have undergone great changes. These altered Soils are often recognized as distinct soil classes that are just as important as natural Soils. The Global Scope of Soils How Soils are distributed around the world helps to determine the quality of environments of the globe. Soil fertility, along with the availability of freshwater, is a basic measure of the capability of an environmental region to produce food for human consumption. We classify Soils according to a system developed by scientists of the U.S. Natural Resources Conservation Service, in cooperation with soil scientists of many other nations. In this book, we’ll discuss the two highest levels of this classification system. The top level contains 12 soil orders . We’ll also mention a few important suborders that make up the second classification level. For this analysis, we will group the soil orders based on four factors that can characterize a particular order: maturity, climate, parent material, and high organic matter (Table 10.1). Figure 10.18 is a map of world soil orders. Let’s look at the soil orders in more detail.

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  Visualizing Physical Geography

  • Timothy Foresman, Alan H. Strahler(Authors)
  • 2012(Publication Date)
  • Wiley

    (Publisher)

  Over time, its irrigation systems became clogged with silt and contaminated with salt, ultimately leading to the downfall of the Babylonians. Problems with irrigation systems have plagued desert populations for centuries. Today, Pakistan, Mexico, and Israel suffer similarly, highlighting the vital role of soil in agriculture. Global Soils 455 CHAPTER OUTLINE Soil Formation 456 • Components of Soil • Soil Horizons • Soil-Forming Processes ■ Video Explorations: Mesopotamia • Factors in Soil Formation ■ What a Geographer Sees: Nature’s Soil Engineers Soil Properties 462 • Soil Color • SoilTexture • Soil Structure • Soil Moisture Soil Chemistry 467 • Acidity and Alkalinity • Colloids The Global Distribution of Soils 468 ■ Where Geographers Click: Understanding Soils • Soils Characterized by Maturity • Soils Characterized by ClimateType • Soils Characterized by Parent Material • Organic Soils ✓ ✓ CHAPTER PLANNER ❑ Study the picture and read the opening story. ❑ Scan the Learning Objectives in each section: p. 456 ❑ p. 462 ❑ p. 467 ❑ p. 468 ❑ ❑ Read the text and study all figures and visuals. Answer any questions. Analyze key features ❑ Process Diagram p. 458 ❑ p. 466 ❑ ❑ Video Explorations, p. 459 ❑ What a Geographer Sees, p. 461 ❑ Where Geographers Click, p. 469 ❑ Geography InSight, p. 470 ❑ Stop: Answer the Concept Checks before you go on. p. 462 ❑ p. 467 ❑ p. 468 ❑ p. 478 ❑ End of chapter ❑ Review the Summary and Key Terms. ❑ Answer the Critical and Creative Thinking Questions. ❑ Answer What is happening in this picture? ❑ Complete the Self-Test and check your answers. This ancient panel from Mesopotamia, decorated with shell, red limestone, and lapis lazuli, depicts a rich bounty of animals, fish, grain, and other goods brought in procession to a banquet. 456CHAPTER15 GlobalSoils S oil is the uppermost layer of the lithosphere and serves as the bio- sphere’s foundation for the vast majority of plants and animals.

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  Consider the Earth

  Environmental Activities for Grades 4 - 8

  • Julie M. Gates(Author)
  • 1999(Publication Date)
  • Libraries Unlimited

    (Publisher)

  The following are several generalizations about soil to keep in mind while studying soil: 1. Soil is composed of decomposed rock particles and plant and animal materials. 2. There is air in the soil, important for living organisms. 3. The soil is made up of three layers: the topsoil, the subsoil, and crumbly rock that rests on solid rock. From Consider the Earth. © 1999 Gates. Teacher Ideas Press. (800) 237-6124. 4 / 1 - S o i l Activity 1: Soil Formation / 5 4. Soil is a water reservoir for plants. 5. Rocks break up in many different ways. They break up by: heating and cooling the force of the wind the cutting action of sand moving water—carrying sand, gravel, and rocks the oxidation of certain minerals weak acids formed from C02 in the air and organic acids released from plant roots freezing water formed in cracks that expands the weight and movement of glaciers wearing down parent rock and grinding it into soil 6. Microorganisms hasten the decay of organic matter. Bacteria and molds break down dead plant and animal remains into fine particles called humus. Activity 1: Soil Formation OBJECTIVE: MATERIALS: RESOURCES: LEVEL: SETTING: TIME: VOCABULARY: To develop an understanding of how soil is formed Rock samples, hot plate, ice, water, thermometer, plastic jug with a lid, limestone/sandstone, vinegar Soil conservation officer, rock and mineral identification books Lower to upper Classroom 30-45 minutes Contraction, expansion, natural resources, renewable From Consider the Earth. © 1999 Gates. Teacher Ideas Press. (800) 237-6124. LESSON DESIGN Some parts of this activity may be optional, depending on the type of parent material available in your area, or a certain kind of rock may need to be purchased or borrowed from the geology department of a local college. Rub two pieces of limestone or sandstone together (bricks or concrete can be substituted).

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  Fundamentals of Physical Geography

  • James Petersen, Dorothy Sack, Robert Gabler, , James Petersen, Dorothy Sack, Robert Gabler(Authors)
  • 2014(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  Variations in color and texture within a horizon are not unusual. Factors Affecting Soil Formation Because of the great variety among parent materials and the processes that affected them, no two Soils are identical in all of their characteristics. One important factor is rock weathering , which refers to the natural processes that break down rocks into smaller fragments (weathering is discussed in detail in a later chapter). Chemical reactions can cause rocks and minerals to decompose, and physical processes also cause the breakup of rocks. Just as statues, monuments, and buildings become weather-beaten over time, rocks exposed to the elements eventually break up and decompose. Well-developed Soils typically exhibit distinct layers in their soil profiles called soil horizons that are distinguished by their physical and chemical properties. Soils are classified largely on the differences in their horizons and the processes responsible for those differences. Soil horizons are designated by a set of letters that refer to their composition, dominant process, or position in the soil profile ( ■ Fig. 9.28). At the surface, but only in locations where there is a cover of decomposed vegetation litter, there will be an O horizon . The “O” designation refers to this horizon’s high content of organic debris and humus. The A horizon , immediately below, is commonly referred to as “topsoil.” In general, A horizons are dark because they contain decomposed organic matter. Beneath the A horizon, certain Soils have a lighter-colored E horizon , named for the action of strong eluvial processes. Below this is the B horizon , a zone of accumulation, where much of the materials removed from the A and E horizons are deposited. The C horizon is the weathered parent material from which the soil has developed—either bedrock, or deposits of rock materials that were transported to the site by a surface process such as running water, wind, or glacial activity.

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