How Do Geology Affect Soil Development

How soils form. Soil is the thin layer of material covering the earth’s surface and it is formed from the weathering of rocks.

  • Parent materials
  • Organisms
  • Climate
  • Topography
  • Time

The soil profile

Soil is the thin layer of material covering the earth’s surface and is formed from the weathering of rocks. It is made up mainly of mineral particles, organic materials, air, water and living organisms—all of which interact slowly yet constantly. Most plants get their nutrients from the soil and they are the main source of food for humans, animals and birds. Therefore, most living things on land depend on soil for their existence. Soil is a valuable resource that needs to be carefully managed as it is easily damaged, washed or blown away. If we understand soil and manage it properly, we will avoid destroying one of the essential building blocks of our environment and our food security.


Video advice: Soil Formation

LNT 134 – Introduction to Soil Science


– Weathering and soil formation

Soil-Net.com – a soils educational portal developedby the National Soil Resources Institute (NSRI), the largest UK national and internationalcentre for research and development, consultancy and training in soils and their interactionwith the atmosphere, land use, geology and water resources.

Weathering may be the name provided to the procedure through which rocks are damaged lower to create soils. Rocks and geological sediments would be the primary parent materials of soils (the types of materials that soils have created). There’s a really wide selection of rocks on the planet, some acidic, some alkaline, some coarse-textured like sands, and a few fine-textured and clayey. It’s in the rocks and sediments that soils inherit their unique texture. If you notice rocks within the landscape you can easily recognize how lengthy the entire process of breaking lower rocks to create soil takes. Actually, it will take over five centuries to create only one centimetre of soil from a few of the harder rocks. Fortunately, in certain respects a minimum of, immeasureable rocks were damaged lower throughout the Ice Age over 10,000 years back and changed into clays, sands or gravels, that condition it had been simpler to create soils. You will find three primary kinds of weathering physical, chemical and biological. Physical weathering may be the influence of processes for example freezing and thawing, wetting and drying, and shrinking and swelling on rocks along with other sediments, resulting in their breakdown into finer and finer particles.

Soil Formation

  1. Introduction
  2. Soil modification during the Anthropocene

The soil formation process is a complex interplay between specific pedogenic processes, creating a set of solid-phase pedogenic features. From: Soil Magnetism, 2017Surface And Groundwater, Weathering and SoilsR. Amundson, in Treatise on Geochemistry (Second Edition), 20147. 1. 4 Conceptual Partitioning of the Earth SurfaceSoil formation is a process strongly driven by the boundary conditions for the soil system. One of the key conditions (e. g., initial state in eqn (1)) is the physical configuration of the landscape, which dictates the nature of the ‘geomorphic surface’: the atmosphere/land boundary. From a physical perspective, landscapes can be stable, erosional, or depositional. While physical erosion or deposition can be driven by wind and other processes, slope-driven transport dominates many soil-mantled landscapes. From this perspective, the three landsurfaces can be defined as a function of slope and curvature (the change in slope with downslope distance):•Stable Landsurface: slope (dz/dx) = 0;•Erosional Landsurface: curvature (d(slope)/dx) = (−)•Depositional Landsurface: curvature = (+)Figure 3 illustrates this very general landscape partitioning.

Pedogenesis

For reproduction by an organism that has not achieved physical maturity, see Paedogenesis.

Parent materials are sorted based on the way they came into existence deposited. Residual materials are mineral materials which have weathered in position from primary foundation. Transported materials are individuals which have been deposited by water, wind, ice or gravity. Cumulose materials are organic matter which has grown and builds up in position.

Pedogenesis (from the Greek pedo-, or pedon, meaning ‘soil, earth,’ and genesis, meaning ‘origin, birth’) (also termed soil development, soil evolution, soil formation, and soil genesis) is the process of soil formation as regulated by the effects of place, environment, and history. Biogeochemical processes act to both create and destroy order (anisotropy) within soils. These alterations lead to the development of layers, termed soil horizons, distinguished by differences in color, structure, texture, and chemistry. These features occur in patterns of soil type distribution, forming in response to differences in soil forming factors.


Video advice: Soil Formation: 5 Soil Factors Part 1

We discuss how soil is formed and what factors affect its properties.


Chapter 8 Weathering, Sediment, and Soil

“Physical Geology”, adaptaed from Physical Geology: First University of Saskatchewan Edition.

Rocks weather when they’re uncovered to come to light conditions. Generally, conditions at Earth’s surface are not the same in the conditions to which the rocks created. Mechanical weathering processes include exfoliation, freeze-thaw, salt crystallization, and also the wedging results of plant growth.

  • What Is Weathering?
  • Mechanical Weathering By Expansion
  • Reasons Rocks Expand
  • Mechanical Weathering by Wedging
  • Frost Wedging
  • Salt Wedging
  • Plant and Animal Activity
  • Erosion
  • Types of Chemical Weathering Reactions
  • Dissolution
  • Hydrolysis
  • Hydration

Controls on Weathering Processes and Rates

Weathering occurs when rock is exposed to the “weather” — to the forces and conditions that exist at Earth’s surface. Rocks that form deep within Earth experience relatively constant temperature, high pressure, have no contact with the atmosphere, and little or no interaction with moving water. Once overlying layers are eroded away and a rock is exposed at the surface, conditions change dramatically. Temperatures vary widely, and pressure is much lower. Reactive gases like oxygen and carbon dioxide are plentiful, and in many climates, water is abundant.

8.5 Weathering and Soil Formation

Weathering is a key part of the process of soil formation, and soil is critical to our existence on Earth. In other words, we owe our existence to weathering, and we need to take care of the soil!

Although rare in Canada, another kind of layer that develops in hot arid regions is called caliche (pronounced ca-lee-chee). It forms in the downward (or in some instances upward) movement of calcium ions, and also the precipitation of calcite inside the soil. When well toned, caliche cements the nearby material together to create a layer which has the consistency of concrete.

Slope

The types of weathering that take place within a region have a major influence on soil composition and texture. For example, in a warm climate where chemical weathering dominates, soils tend to be richer in clay. Soil scientists describe soil texture in terms of the relative proportions of sand, silt, and clay (Figure 8. 21). Sand and silt components are dominated by quartz, with lesser amounts of feldspar and rock fragments. The clay component is dominated by clay minerals.

Soils

In highly weathered settings, the mineral soil has lost most of its nutrients, and the store of nutrients that remains is mostly found in organic matter. In weathered soils, only the top 25 cm (10 inches) or so may be very biologically active, and rooting depths are very shallow. If this thin layer is lost to erosion, the underlying mineral soil may be infertile and incapable of rapid recovery.

What is “soil”? – It’s sometimes easy to take the soil beneath our feet for granted. Yet soil has always been with us—it is the foundation of our houses and roads, and from the soil comes our food, fiber, and paper. Soil is the interface between living earth and solid rock, between biology and geology. Soils are the principal medium of plant growth, and they provide habitat for a myriad of organisms—particularly decomposers. Soils store and purify water, and they exchange gasses with the atmosphere. Soils support agriculture and natural ecosystems, provide a grassy surface for our parks, and fodder for our gardens. Everyone, everywhere, every day, depends upon the soil.

The Effect of Parent Material and Soil Development on Nutrient Cycling in Temperate Ecosystems on JSTOR

The parent material of a soil determines the original supply of those nutrient elements that are released by weathering and influences the balance between nutrient loss and retention. Organic acids and exudates produced by microorganisms and plants enhance the weathering of minerals and the release of nutrients. Nutrients may be stored in organic cycles or as ions adsorbed to clay and organic matter. Nutrients are lost mainly by leaching, both as dissolved ions and when associated with soluble organic components. Soil formation evidently affects these processes and modifies the environment at different depths as soil horizons develop. Strong interactions between mineral and organic colloids occur where most residues are added below ground, as in grasslands, or mixed with mineral soil by faunal activity, as in some forests. These systems tend to be nutrient conserving. The addition of organic residues to the soil surface often results in slow decomposition, the tie-up of many nutrients in biologically resistant humic materials, and the generation of organic acids that are active in leaching and chelation.


Video advice: Soil and Soil Dynamics

006 – Soil and Soil Dynamics


[FAQ]

How does geology affect soil?

Both the mechanical breakup of rocks and the chemical weathering of minerals contribute to soil formation. The downward percolation of water brings dissolved ions and also facilitates chemical reactions. Soil forms most readily under temperate to tropical conditions, and moderate precipitation.

How the geology controls soil formation?

Soil minerals form the basis of soil. They are produced from rocks (parent material) through the processes of weathering and natural erosion. Water, wind, temperature change, gravity, chemical interaction, living organisms and pressure differences all help break down parent material.

What affects soil development?

The whole soil, from the surface to its lowest depths, develops naturally as a result of these five factors. The five factors are: 1) parent material, 2) relief or topography, 3) organisms (including humans), 4) climate, and 5) time.

What is the relationship between geology and soil science?

Future interactions between geology and soil science will occur on issues such as: water in the vadose zone; risks due to Earth movements; and functions of soils in ecosystems. We predict and also welcome more communication between the two disciplines, as solutions to some of these problems are demanded by society.

How does geology affect agriculture?

Agrogeology can also be defined as the application of geology to problems in agriculture, particularly in reference to soil productivity and health. ... The overall objective is to advance agricultural production by using geological resources to improve chemical and physical aspects of soil.

Erwin van den Burg

Stress and anxiety researcher at CHUV2014–present
Ph.D. from Radboud University NijmegenGraduated 2002
Lives in Lausanne, Switzerland2013–present

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