Lecture

Soil Formation: Horizons and Factors

Graph Chat

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

Description

This lecture explores the process of soil formation, focusing on the concept of soil horizons and key factors influencing soil development. Topics include the distribution of soils worldwide, the accumulation of clay and oxyhydroxides, and extreme cases like Podzols. The instructor discusses the role of climate, biological activity, topography, parent material, and time in shaping soil properties. Examples of humus-rich soils like Histosols and Mollisols are presented, along with mechanisms of Fe and Al transport in organic complexes. The lecture also covers nutrient-limited soils and the impact of small organic molecules on soil formation.

Official source

Ontological neighbourhood

Biology

Ecology: Ecosystems

Related concepts (31)

Soil horizon

A soil horizon is a layer parallel to the soil surface whose physical, chemical and biological characteristics differ from the layers above and beneath. Horizons are defined in many cases by obvious physical features, mainly colour and texture. These may be described both in absolute terms (particle size distribution for texture, for instance) and in terms relative to the surrounding material, i.e. 'coarser' or 'sandier' than the horizons above and below. The identified horizons are indicated with symbols, which are mostly used in a hierarchical way.

Soil

Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life of plants and soil organisms. Some scientific definitions distinguish dirt from soil by restricting the former term specifically to displaced soil. Soil consists of a solid phase of minerals and organic matter (the soil matrix), as well as a porous phase that holds gases (the soil atmosphere) and water (the soil solution). Accordingly, soil is a three-state system of solids, liquids, and gases.

Soil formation

Soil formation, also known as pedogenesis, is the process of soil genesis 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.

Podzol

In soil science, podzols are the typical soils of coniferous or boreal forests and also the typical soils of eucalypt forests and heathlands in southern Australia. In Western Europe, podzols develop on heathland, which is often a construct of human interference through grazing and burning. In some British moorlands with podzolic soils, cambisols are preserved under Bronze Age barrows. Podzol means "under-ash" and is derived from the Russian под (pod) + зола́ (zola); the full form is подзо́листая по́чва (podzolistaya pochva), meaning "under-ashed soil".

Soil biology

Soil biology is the study of microbial and faunal activity and ecology in soil. Soil life, soil biota, soil fauna, or edaphon is a collective term that encompasses all organisms that spend a significant portion of their life cycle within a soil profile, or at the soil-litter interface. These organisms include earthworms, nematodes, protozoa, fungi, bacteria, different arthropods, as well as some reptiles (such as snakes), and species of burrowing mammals like gophers, moles and prairie dogs.

Related lectures (50)

Soil Sciences: Main Soil Types in Switzerland

Covers the main soil types in Switzerland and their fertility and ecological functions.

Soil Sciences: Living Organisms and Soil Structure

Delves into the functions of living organisms in soil and their impact on soil structure and plant growth.

Soil Diversity: Formation and Factors

Explores soil diversity, formation factors, and human impact on soil evolution.

Soil as Dwelling Place

Explores the interdependence of soil and dwelling in agroecological farms, emphasizing soil care and alternative human dwellings.

Soil Sciences: Brunisols and Luvisols