Illuviation in Geography
In geography, different characteristics and properties of water, soil, air, weather are discussed. Illuviation is one of the most important properties of soil. Soil has different layers depending on the materials and density. Illuviation is a kind of soil mixture, which is made by the accumulation of suspended or dissolved soil materials. The materials are accumulated in a particular area. The accumulation is the result of leaching from another area. The soil mixture contains iron, clay, humus, and other soil materials. In this article, we are going to define illuviation and the soil illuviation process in detail. Illuviation is an essential topic of geography as well as geology.
Illuviation Definition
The Illuviation of soil is a vital part of garbage management. To reduce the harm of garbage produced from soil, illuviation is a modern process. The accumulation of dissolved soil materials is called soil illuviation. The soil materials contain clay, humus, some metals such as iron, copper, zinc, etc, and some salts. The soil mixture has a new colour, density, and consistency for the different materials.
Illuviation Process
As a part of garbage management, soil illuviation is the next process of leaching. After leaching, the materials such as metals, salts, clay, humus are washed out and accumulated in a particular area. All the materials are mixed in that area in a layer and form a mixture, which contains a new colour and consistency. The mixture is formed by small particles of the materials and the particles are in the colloidal size. The area of illuviation is called the illuvial zone, which is usually a low area. In illuviation, the materials are displaced from one layer to another layer of soil. The materials are accumulated in the area for a long time. Thus, the mixture is produced and the entire process is complete by the displacement of materials by rainwater.
Contains of Illuviation
Illuviation of soil is a displacement process of soil materials across a soil profile. The materials, which are displaced from one layer to another are called illuvium in the illuviation process. Illuvium includes clay, humus, salts (NaCl, CaCl2), metals (iron, zinc, copper), oxides, etc. The displacement of illuvium is of two types- chemical and mechanical. In the mechanical process, the materials are accumulated in an area and the mixture is done. In the chemical process, the materials are transported with rainwater and the mixture is produced by the action of rainwater and the illuvium. These are the main soil materials in the process of soil illuviation.
Soil Horizon For Illuviation
The illuviation process can be completed by chemical or mechanical causes. If the displacement is by rainwater and the mixture is produced by the action of water, that is the chemical cause, if the displacement is the next step of leaching and the mixture is produced by the accumulation of dissolved soil materials, that is mechanical causes. Both the processes take place in a particular soil horizon. The horizon is known as the A horizon of soil, which is also the zone of illuviation. This horizon has formed below an A, E, or O horizon. B horizon is the evidence of carbonate removal.
Solved Examples
1. Give the Illuviation Soil Definition.
Solution: The accumulation of dissolved soil materials in a particular area or the displacement of the soil materials in a layer from another is called illuviation.
2. What are the Processes of Soil Illuviation?
Solution: The main two processes of illuviation are chemical and mechanical. If the process is completed by the action of rainwater, it is chemical. On the other hand, the mechanical process is done by the accumulation of dissolved soil materials after leaching.
3. What are the Soil Materials For Illuviation?
Solution: The soil materials for illuviation are called illuvium. Illuvium includes clay, humus, metals (iron, aluminum, copper, zinc, etc), salt (NaCl, CaCl2), oxides (silicon dioxide, iron oxide, aluminum oxide), carbonates, etc.
4. What is the Soil Horizon in Illuviation?
Solution: The illuviation process takes place in a particular area or layer of soil. The soil horizon for illuviation is called the B horizon and the area is called the zone of illuviation.
5. What is the Importance of Illuviation?
Solution: Illuviation is an essential process of garbage management. By this process, a new soil mixture is produced with new colour and consistency.
FAQs on Illuviation
1. What is illuviation in the context of geography?
Illuviation is a fundamental soil-forming process involving the accumulation or deposition of soil materials in a lower layer, or horizon, of the soil. These materials, such as clay, iron, or humus, are transported downward from an upper layer by percolating water. This process is responsible for creating distinct layers within a soil profile.
2. What is the primary difference between illuviation and eluviation?
The primary difference lies in the direction of material movement. Eluviation is the process of removal or 'washing out' of materials from an upper soil horizon (the A-horizon). In contrast, illuviation is the process of accumulation or 'washing in' of these same materials into a lower soil horizon (the B-horizon). Think of eluviation as 'Exit' and illuviation as 'Into'.
3. How does the process of illuviation occur in soil?
The process of illuviation happens in sequential steps. First, rainwater infiltrates the topsoil and dissolves or suspends fine particles like clay and organic matter. This downward movement of water and materials through the upper soil layers is called leaching or eluviation. When this water reaches a lower layer, changes in chemical conditions or a decrease in water flow cause the suspended materials to be deposited and accumulate. This deposition is the core of the illuviation process.
4. Which soil horizon is known as the zone of illuviation and why?
The B-horizon, located beneath the topsoil (A-horizon), is known as the zone of illuviation. It earns this name because it is the primary layer where materials leached from the A-horizon get deposited. This accumulation gives the B-horizon its characteristic features, such as higher clay content, denser structure, and often a reddish or brownish colour due to iron oxide accumulation.
5. What types of materials are commonly deposited during illuviation?
Several types of materials are commonly deposited, significantly altering the soil's composition. These include:
Silicate Clays: The most common material, which increases the density and water-holding capacity of the B-horizon.
Iron and Aluminium Oxides: These give the subsoil its distinct reddish, yellowish, or brownish colours.
Organic Matter (Humus): Soluble organic compounds can be transported downwards and accumulate.
Carbonates: In arid or semi-arid regions, calcium carbonate can accumulate to form a hard layer known as caliche.
6. Why is illuviation a crucial process in soil profile development?
Illuviation is crucial because it is directly responsible for the differentiation of soil horizons, which is the foundation of soil profile development. By concentrating materials like clay and nutrients in the B-horizon, it directly influences the soil's physical and chemical properties, including its texture, structure, fertility, and water retention capabilities. This, in turn, determines the type of vegetation that can grow and the land's agricultural potential.
7. Can illuviation happen without eluviation? Explain their relationship.
No, illuviation cannot happen without eluviation. The two processes are two sides of the same coin, representing a single process of translocation (movement of materials) within the soil. Eluviation is the 'source' process that removes and transports materials from an upper layer. Illuviation is the 'destination' process where these transported materials are deposited in a lower layer. Without the removal of material from above (eluviation), there would be nothing to accumulate below (illuviation).
8. What key factors influence the rate and intensity of illuviation?
The rate and intensity of illuviation are influenced by several environmental factors. The most significant is climate, specifically the amount of rainfall, as more water leads to more leaching and subsequent deposition. Other factors include soil texture (sandy soils allow for more rapid translocation than clayey ones), topography (steeper slopes may have less water infiltration, reducing illuviation), and the type of vegetation, which affects the amount and type of organic matter available for transport.
