Soil ecology
Encyclopedia
Soil ecology is the study of the interactions among soil organisms, and between biotic and abiotic aspects of the soil environment. It is particularly concerned with the cycling of nutrients
, formation and stabilization of the pore structure
, the spread and vitality of pathogens, and the biodiversity of this rich biological community
.
is made up of a multitude of physical
, chemical
, and biological
entities, with many interactions occurring among them. Soil is a variable mixture of broken and weathered minerals and decaying organic matter. Together with the proper amounts of air and water, it supplies, in part, sustenance for plants as well as mechanical support.
The diversity and abundance of soil life
exceeds that of any other ecosystem
. Plant establishment, competitiveness, and growth is governed largely by the ecology below-ground, so understanding this system is an essential component of plant sciences and terrestrial ecology.
. They range in size from the tiniest one-celled bacteria
, algae
, fungi, and protozoa
, to the more complex nematodes and micro-arthropods, to the visible earthworm
s, insects, small vertebrates, and plants. As these organisms eat, grow, and move through the soil, they make it possible to have clean water, clean air, healthy plants, and moderated water flow.
There are many ways that the soil food web is an integral part of landscape processes. Soil organisms
decompose organic compounds, including manure
, plant residues, and pesticides, preventing them from entering water and becoming pollutants. They sequester nitrogen and other nutrients that might otherwise enter groundwater, and they fix nitrogen from the atmosphere, making it available to plants. Many organisms enhance soil aggregation and porosity
, thus increasing infiltration
and reducing surface runoff
. Soil organisms prey on crop pests and are food for above-ground animals.
, Fundamentally, researchers are interested in understanding the interplay among microorganisms, fauna
, and plants, the biogeochemical processes they carry out, and the physical environment in which their activities take place, and applying this knowledge to address environmental problems.
Example research projects are to examine the biogeochemistry
and microbial ecology of septic drain field
soils used to treat domestic wastewater
, the role of anecic earthworms in controlling the movement of water and nitrogen cycle
in agricultural soils
, and the assessment of soil quality in turf production.
Of particular interest is to understand the roles and functions of arbuscular
mycorrhizal fungi in natural ecosystems. The effect of anthropic soil conditions
on arbuscular mycorrhizal fungi, and the production of glomalin
by arbuscular mycorrhizal fungi are both of particular interest due to their roles in sequestering atmospheric carbon dioxide
.
Biogeochemistry
Biogeochemistry is the scientific discipline that involves the study of the chemical, physical, geological, and biological processes and reactions that govern the composition of the natural environment...
, formation and stabilization of the pore structure
Porosity
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...
, the spread and vitality of pathogens, and the biodiversity of this rich biological community
Soil life
Soil life or soil biota is a collective term for all the organisms living within the soil.-Overview:In balanced soil, plants grow in an active and steady environment. The mineral content of the soil and its heartiful structure are important for their well-being, but it is the life in the earth that...
.
Overview
SoilSoil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
is made up of a multitude of physical
Soil physics
Soil physics is the study of soil physical properties and processes. It is applied to management and prediction under natural and managed ecosystems. Soil physics deals with the dynamics of physical soil components and their phases as solids, liquids, and gases. It draws on the principles of...
, chemical
Soil chemistry
Soil chemistry is the study of the chemical characteristics of soil. Soil chemistry is affected by mineral composition, organic matter and environmental factors.-History:...
, and biological
Soil biology
Soil biology is the study of microbial and faunal activity and ecology in soil. These organisms include earthworms, nematodes, protozoa, fungi, bacteria and different arthropods...
entities, with many interactions occurring among them. Soil is a variable mixture of broken and weathered minerals and decaying organic matter. Together with the proper amounts of air and water, it supplies, in part, sustenance for plants as well as mechanical support.
The diversity and abundance of soil life
Soil life
Soil life or soil biota is a collective term for all the organisms living within the soil.-Overview:In balanced soil, plants grow in an active and steady environment. The mineral content of the soil and its heartiful structure are important for their well-being, but it is the life in the earth that...
exceeds that of any other ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
. Plant establishment, competitiveness, and growth is governed largely by the ecology below-ground, so understanding this system is an essential component of plant sciences and terrestrial ecology.
Features of the ecosystem
- Moisture itself becomes a major limiting factor on land. Terrestrial organisms are constantly confronted with the problem of dehydration. Transpiration or evaporation of water from plant surfaces is an energy dissipating process unique to the terrestrial environment.
- Temperature variations and extremes are more pronounced in the air than in the water medium.
- On the other hand, the rapid circulation of air throughout the globe results in a ready mixing and remarkably constant content of oxygen and carbon dioxide.
- Although soil offers solid support, air does not. Storing skeletons have been evolved in both land plants and animals and also special means of locomotion have been evolved in the latter.
- Land, unlike the ocean, is not continuous; there are important geographical barriers to free movement.
- The nature of the substrate, although important in water is especially vital in terrestrial environment. Soil, not air, is the source of highly variable nutrients; it is a highly developed ecological subsystem.
Soil food web
An incredible diversity of organisms make up the soil food webFood web
A food web depicts feeding connections in an ecological community. Ecologists can broadly lump all life forms into one of two categories called trophic levels: 1) the autotrophs, and 2) the heterotrophs...
. They range in size from the tiniest one-celled bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, fungi, and protozoa
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...
, to the more complex nematodes and micro-arthropods, to the visible earthworm
Earthworm
Earthworm is the common name for the largest members of Oligochaeta in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening posterior to the female pores, even though the internal male segments are anterior to the female...
s, insects, small vertebrates, and plants. As these organisms eat, grow, and move through the soil, they make it possible to have clean water, clean air, healthy plants, and moderated water flow.
There are many ways that the soil food web is an integral part of landscape processes. Soil organisms
Soil life
Soil life or soil biota is a collective term for all the organisms living within the soil.-Overview:In balanced soil, plants grow in an active and steady environment. The mineral content of the soil and its heartiful structure are important for their well-being, but it is the life in the earth that...
decompose organic compounds, including manure
Manure
Manure is organic matter used as organic fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen, that are trapped by bacteria in the soil...
, plant residues, and pesticides, preventing them from entering water and becoming pollutants. They sequester nitrogen and other nutrients that might otherwise enter groundwater, and they fix nitrogen from the atmosphere, making it available to plants. Many organisms enhance soil aggregation and porosity
Porosity
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...
, thus increasing infiltration
Infiltration (hydrology)
Infiltration is the process by which water on the ground surface enters the soil. Infiltration rate in soil science is a measure of the rate at which soil is able to absorb rainfall or irrigation. It is measured in inches per hour or millimeters per hour. The rate decreases as the soil becomes...
and reducing surface runoff
Surface runoff
Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
. Soil organisms prey on crop pests and are food for above-ground animals.
Research
Research interests span many aspects of soil ecology and microbiologyMicrobiology
Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell , cell clusters or no cell at all . This includes eukaryotes, such as fungi and protists, and prokaryotes...
, Fundamentally, researchers are interested in understanding the interplay among microorganisms, fauna
Fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...
, and plants, the biogeochemical processes they carry out, and the physical environment in which their activities take place, and applying this knowledge to address environmental problems.
Example research projects are to examine the biogeochemistry
Biogeochemistry
Biogeochemistry is the scientific discipline that involves the study of the chemical, physical, geological, and biological processes and reactions that govern the composition of the natural environment...
and microbial ecology of septic drain field
Septic drain field
Septic drain fields, also called leach fields or leach drains are used to remove contaminants and impurities from the liquid that emerges from the septic tank. A septic tank, the septic drain field, and the associated piping compose a complete septic system. The septic drain field is effective for...
soils used to treat domestic wastewater
Wastewater
Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations...
, the role of anecic earthworms in controlling the movement of water and nitrogen cycle
Nitrogen cycle
The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out by both biological and non-biological processes. Important processes in the nitrogen cycle include fixation, mineralization, nitrification, and denitrification...
in agricultural soils
Agricultural soil science
Agricultural soil science is a branch of soil science that deals with the study of edaphic conditions as they relate to the production of food and fiber. In this context, it is also a constituent of the field of agronomy.-History:...
, and the assessment of soil quality in turf production.
Of particular interest is to understand the roles and functions of arbuscular
Arbuscular mycorrhiza
An arbuscular mycorrhiza is a type of mycorrhiza in which the fungus penetrates the cortical cells of the roots of a vascular plant....
mycorrhizal fungi in natural ecosystems. The effect of anthropic soil conditions
Terra preta
Terra preta is a type of very dark, fertile anthropogenic soil found in the Amazon Basin. Terra preta owes its name to its very high charcoal content, and was indeed made by adding a mixture of charcoal, bone, and manure to the otherwise relatively infertile Amazonian soil, and stays there for...
on arbuscular mycorrhizal fungi, and the production of glomalin
Glomalin
Glomalin is a glycoprotein produced abundantly on hyphae and spores of arbuscular mycorrhizal fungi in soil and in roots.As a glycoprotein, glomalin stores carbon in both its protein and its carbohydrate subunits. It permeates organic matter, binding it to silt, sand, and clay particles...
by arbuscular mycorrhizal fungi are both of particular interest due to their roles in sequestering atmospheric carbon dioxide
Carbon dioxide sink
A carbon sink is a natural or artificial reservoir that accumulates and stores some carbon-containing chemical compound for an indefinite period. The process by which carbon sinks remove carbon dioxide from the atmosphere is known as carbon sequestration...
.
External links
- Floor, Dr. J. Anthoni. 2000. Soil Ecology. Url last accessed 2006-04-18
- Soil Ecology Section of the Ecological Society of America. Url last accessed 2006-04-18
- Yahoo! Soil Ecology Directory. Url last accessed 2006-04-18