Rashid's Blog: A Place for Inquisitive Learners

Global warming, driven by human emissions of greenhouse gases, is not just altering our climate; it is triggering a catastrophic loss of biodiversity…

Global Warming results the Loss of Biodiversity

This tiny primate may be the first lemur species to go extinct in the 21st century.

The World’s Smallest Primate, Madame Berthe’s Mouse Lemur, May Be Extinct According To Worried Conservationists

Accumulation of Materials

Accumulation of materials in the soil formation process refers to the addition and buildup of various substances that contribute to soil development and fertility. These materials accumulate from both organic and inorganic sources, influenced by environmental factors and biological activity. Materials are added to the soil.

Organic Matter Accumulation and Inorganic Matter Accumulation

Leaching and Other Losses

Leaching in soil formation is the process by which water, usually from precipitation or irrigation, percolates through the soil and dissolves soluble substances such as minerals, nutrients, and colloids, carrying them downward from the upper soil layers to lower horizons or out of the soil profile entirely.
Leaching is the removal of soluble components of the soil Column.

Transformation and Illuviation

Transformation

Transformation refers to the chemical and biological alteration of soil materials within the soil profile. This includes processes such as:

• Chemical weathering of minerals, for example, the breakdown of primary minerals like feldspar into secondary minerals like clay.
• Decomposition of organic matter into humus through biological activity.
• Conversion of coarse organic material into decay-resistant organic compounds.
• Changes in mineralogical and chemical composition that modify soil texture, structure, and fertility.

Transformation helps in the maturation of soil by creating stable components like clay minerals and humus, which improve nutrient availability and water retention in the soil.

Illuviation

Illuviation is the process involving the translocation and accumulation of materials leached from upper soil layers into lower horizons. These materials may include:

• Clay particles
• Organic matter (humus)
• Iron and aluminum oxides
• Salts and other minerals

Illuviation typically results in the formation of an illuvial horizon (often the B horizon), characterized by accumulation of these fine materials, which gives distinct color, texture, and density differences compared to upper layers.

Podsolisation

Strongly acidic solutions cause the breakdown of clay minerals. Podzolisation is a specific soil formation process that occurs under cool, humid conditions, typically in acidic environments influenced by coniferous or heath vegetation. It involves the leaching (eluviation) of organic acids and minerals, such as iron (Fe) and aluminium (Al), from the upper soil horizons and their subsequent accumulation (illuviation) in the subsoil.

Laterization

Laterization is a soil formation process characteristic of tropical and subtropical climates with high temperatures and heavy rainfall. It involves the intense chemical weathering and leaching of rock and soil minerals, resulting in the removal of silica, calcium, magnesium, and other soluble elements. This process leaves behind concentrated deposits of iron and aluminium oxides, which give the soil a distinctive reddish-brown colour and a hard, compact texture known as laterite.

Calcification

Calcification is a soil formation process that occurs primarily in warm, semi-arid to arid environments, often under grassland vegetation. It involves the precipitation and accumulation of calcium carbonate (CaCO3) within the soil profile, typically in the B horizon. This happens because calcium dissolved in water moves downward or upward by capillary action, and when conditions such as high temperature and low carbon dioxide concentration prevail, calcium carbonate precipitates out and accumulates.

Gleying

Gleying is a soil formation process that occurs under waterlogged, anaerobic conditions where oxygen availability is severely limited. This process leads to the formation of a gley horizon characterized by bluish-grey, greenish, or grey colors in the soil profile. The lack of oxygen causes iron compounds in the soil to be chemically reduced from ferric (Fe3+) to ferrous (Fe2+) forms. These reduced iron compounds either get removed from the soil or segregate into mottles or concretions, giving the soil its distinctive coloration.

Pedoturbation

Pedoturbation is a soil formation process involving the physical mixing and churning of soil materials. This process leads to the mixing of soil horizons and affects soil structure and composition. Pedoturbation plays a crucial role in soil genesis by destratifying and redistributing organic and mineral matter within the soil profile.

Types of Pedoturbation:

Argillipedoturbation: Mixing caused by the physical swelling and shrinking of clay soils (e.g., Vertisols or black cotton soils), leading to churning and movement of soil materials.

Faunal Pedoturbation: Mixing caused by soil-dwelling animals such as earthworms, ants, rodents, and other burrowing fauna.

Floral Pedoturbation: Mixing caused by plant roots and vegetation activities, including processes like tree tipping that create pits and mounds.

Read More:

Factors Affecting Process of Soil Formation

Podzolization of Soil

Childe’s Urban Revolution and Mumford’s Organic City Theory offer contrasting explanations for urban origins and evolution. Childe’s theory is archaeological and materialist, focusing on structural changes driven by agriculture, while Mumford’s perspective is sociological and organic, emphasizing qualitative growth, human relationships, and the integration of city life with environmental and cultural factors.

Childe’s Urban Revolution

• Childe describes the urban revolution as a process by which small, kin-based agricultural settlements developed into complex urban societies.
• He identifies ten key features of early cities: increased size, full-time specialists, concentration of surplus as taxes, monumental architecture, a ruling class, writing, predictive sciences, artistic development, trade, and state organization based on residency not kinship.
• The driving mechanism is the agricultural surplus, which enables specialization, stratification, and centralized authority, leading to state formation.
• Childe’s model emphasizes the transition from technology-driven, surplus-based village life to urban complexity characterized by bureaucracy and hierarchy.

Mumford’s Organic City Theory

• Mumford, in contrast, views the city not merely as a product of material or technological change but as an evolving organism.
• His organic theory highlights the changing means of livelihood, spatial interaction, and the evolution of social hierarchies and cohesion as qualitative markers of urban growth.
• Mumford stresses the need for harmony between the built environment, social relationships, and nature, warning that unrestrained urban growth causes social pathology and environmental decline.

He favours smaller, well-bounded, socially cohesive “polynucleated” settlements rather than sprawling mega-cities