Edafogenesis: What is, stages and soil formation factors

Edafogenesis is defined as the process of formation of a soil, that is, the set of transformations that a natural system has experienced to form the soil. This process implies the interaction of factors such as climate, mother rock, topography, organisms and time, which act together to give rise to horizons and specific properties.

• Initial stage: soil formation begins with the fragmentation of the original rocks and the organic remains that colonize the material. Physical disaggregation allows air and water entry, which activates biological and chemical processes. The minerals are altered by releasing ions that are incorporated into the soil solution, forming gels or recombining in new secondary minerals. At the same time, the remains of plants and animals suffer transformations that originate humus, organic matter stabilized fundamental in Edafogenesis. During this process, simple compounds, water and gases are also released, although the latter come largely from the atmosphere. This phase marks the initial differentiation of the constituents of the soil.
• Final stage: At this stage, the constituents generated in the initial phase (minerals, humus, water, gases, solutions) are reorganized and suffer from mixing and differentiation processes. If they remain in place, they evolve towards a well developed soil; If they are transported, they form sediments that can be rented later. The transformation here is more intense: the original minerals are modified physically and chemically, interact with organic fraction and generate stable structural aggregates. In this phase the mobilizations of substances that define the morphology and chemical properties of the soil predominate. In this way, edaphic horizons are consolidated with their own and recognizable characteristics.

The factors that influence the soil formation process are five: original material, climate, biological activity, time and relief. These cause so much diversity of soils.

Original material

The mother rock determines numerous characteristics of the soils, mainly of young soils. With respect to superficial horizons, the soil is formed by contribution material outside the underlying rocks such as volcanic or salts present in rainwater. The chemical properties of the material have great influence on the evolution of the soil. The soils formed on rocks rich in bases often have Illita or Montmorillonite clay, a greater exchange capacity, more organic matter content and can be more fertile. Acids can give rise to soils with caolinite or vermiculite clay and in general they are more leachate and are poor nutritionally.

Climate

The weather is the most influential factor on a large scale in the formation and differentiation of soils. Temperature and precipitation regulate mineral weathering, biological activity and water dynamics in the profile. Worldwide, soil maps usually coincide with climate maps and associated vegetation.

Time

Time acts as a cumulative factor: over hours or stations of the year, soil properties fluctuate (temperature, humidity, pH, nutrients), but in decades or centuries the soil passes through youth phases, maturity and senility. Paleosuelos show how some profiles retain traces of past climates, even when current conditions differ. Thus, time not only allows the evolution of horizons, but also prints memories in the soil that reflect ancient processes, modifying its morphology and composition.

Relief

The relief conditions the circulation of water, erosion and the accumulation of materials, influencing the distribution and characteristics of soils in the same environment. In high and slope areas, erosive processes predominate, while in low or depressed areas sediments and nutrients accumulate. In addition, the relief interacts with other factors such as climate and original material, accelerating or delaying training. In pronounced earrings, soils are young and underdeveloped; In valleys and plains, they are usually deeper and more fertile.

Biological factors

The soil biota plays a key role. Animals mix and transport materials, contributing to aeration and the formation of humus. Plants, through the activity of their roots and organic remains, modify the structure, pH and fertility. The vegetation protects the erosion soil, regulates the microclimate and enriches the superficial horizons. Microorganisms transform nutrients and support biogeochemical cycles. The human being deeply alters the evolution of soil through agriculture, deforestation or contributions of organic matter. Together, life in the soil accelerates its transformation and defines much of its current characteristics.

Edafogenetic processes are the mechanisms that, acting on the original material under the influence of the forming factors (climate, relief, biota, time), generate and differentiate soil horizons. Among the main ones we can highlight:

• Humification: Transformation of fresh organic matter in humus, which stabilizes nutrients and improves the structure of the soil.
• Mineralization: decomposition of humus and other organic compounds in simple mineral forms, releasing nutrients available for plants.
• Decalcification: Dissolution and loss of carbonates due to infiltration water, frequent in wet climates.
• Leaching: Washing of nutrients and soluble salts towards deeper horizons or outside the soil profile.
• Eluviation: output or migration of fine particles (clays, oxides, organic matter) from the upper horizons.
• Iliviation: accumulation of those same particles in lower horizons (B), forming argilic horizons, spones, etc.
• Salinization: accumulation of soluble salts in the soil, typical of arid climates or poorly drained soils.
• Laterization: strong weathering in humid tropical climates that concentrates iron and aluminum oxides.
• Podsolization: formation of acid soils in cold and humid climates, where organic complexes drag iron and aluminum towards deeper horizons.
• Gleization: Iron reduction in water saturation conditions, causing gray and greenish colors in the profile.

• Life support: Thanks to the edafogenetic processes, the soil acquires physical, chemical and biological properties that allow the growth of plants and, consequently, support entire trophic chains.
• Regulation of biogeochemical cycles: the soil regulates and stores essential nutrients such as nitrogen, phosphorus, potassium, carbon, among others, acting as a reservoir that recycles matter between the biosphere, atmosphere and hydrosphere.
• Water regulation: the structure and porosity of the soil control the infiltration, storage and movement of water, influencing the recharge of aquifers and the mitigation of floods or droughts.
• Diversity of soils: Edafogenesis generates a great diversity of global soils.
• Human use: Understanding how soils are formed and evolved is essential for agriculture, natural resources management, conservation and environmental restoration.

How long does it take to form a ground?

The formation of a soil is a very slow process. It may take more or less time to form according to the intensity of the forming factors, since at a higher temperature, the speed will be accelerated and greater presence of organisms both macro, meso or micros, the speed of formation will be greater.

What is the difference between Edafogenesis and pedagogenesis?

Both terms are used almost as synonyms, but there is a subtle difference. Edafogenesis refers to the general process of training and evolution of the soil from the mother rock to the development of horizons while pedogenesis focuses more on specific and current mechanisms that act in a specific soil (leaching, accumulation of humus, salinization, etc.).

What types of soils are formed with Edafogenesis?

With Edafogenesis, a great diversity of soils can be formed, among them:

• Soils of arid or semi -arid areas: such as aridisols, characterized by their low organic matter and rapid water absorption.
• Fertile grass or temperate soils: such as Molisols, rich in humus, dark and with good drainage, ideal for agriculture.
• Lateritic or ferral tropical soils: deep, acidic and rich in iron and aluminum oxides, with abundant tree vegetation.
• High moisture or swampy soils: such as histosoles, rich in organic matter and with a tendency to water saturation.
• Frías regions soils: such as gelisols or criesoles, which remain frozen a good part of the year.
• Young or poorly developed soils: such as Entisols, formed by recent sediments and with little horizon differentiation.
• Soils with expansible clays: such as vertisols, which crack when driving and can hinder agriculture.

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