Soil

Soil is the thin and fragile layer forming Earth's epidermis. It is a dynamic, loose and porous body of variable thickness (between a few centimetres and a few metres). Soil is formed by continuous transformations of the initial subsurface material (rock or deposit) under the influence of physical, physicochemical, chemical and biological processes. It is, with the oceans, one of the 2 main components of Earth in which life is particularly active. Soil is the source and the place of development of almost all human activities, and human life greatly depends on it.

Soil is at the hearth of terrestrial ecology. It is part of a multitude of landscapes and ECOSYSTEMS (forested, agricultural, wet lands, anthropogenic) where it evolves while interacting with the other constituents (water, air, vegetation, fauna). The active processes in soil strongly influence terrestrial ecosystems and make it one of the most important resources on Earth.

The 5 key roles of soil show its importance for human kind: 1. Soil contributes to PLANT growth by acting as a support and providing core nutrients as well as a favourable environment for root development. Soil properties have an impact on the type of vegetation, such as calcareous soil versus chalk plant (a plant that grows well in this type of soil), and on the number and type of animal species that can settle in a given environment. 2. Soil cleanses the water. It acts as a living filter for drinking water. 3. Soil is a recycling champion, especially of the biosphere carbon that it stores in great part. 4. Soil provides a habitat for a multitude of living organisms (bacteria, worms, rodents). 5. Soil acts as building material or support for a number of infrastructures (buildings, roads, airports). Knowledge of soil properties is of most importance in all engineering work.

Societies have used and continue to use soil in their own ways for agriculture, ranching, leisure, forest exploitation, landspreading wastes, as building materials, for house, building or road foundations, as metals (iron, aluminium, gold), as a source of energy (biofuels), and so on. The biomass supported by the soil makes possible the production of biofuels such as bioethanol and biodiesel.

As opposed to the widespread belief, soil is not a renewable RESOURCE, at least at the human scale. In fact, the progressive degradation of its qualities, caused by the abusive use of lands or EROSION, is alarming. This degradation progresses very fast and exceeds by far regeneration by the natural alteration of rocks.

The current world context (demographic growth, the growing scarcity of natural and food resources, the overexploitation of ecosystems, the degradation of the ENVIRONMENT, technological changes such as genetically modified organisms [OGMs] and cloning) and the challenges that humankind will face to survive in the 21st century make it necessary to find innovative ways to protect the environment while producing enough food and biomass. Soil will be one of the most solicited resources to meet humankind's endless needs.

See also SOIL SCIENCE; SOIL CONSERVATION; SOIL CLASSIFICATION; AGRICULTURAL SOIL PRACTICES.

Author M. BLACKBURN

Links to Other Sites
Soil Landscapes of Canada
This site features photographs of typical soil landscapes found in various regions of Canada. See also the glossary of soil science terminology. From Agriculture and Agri-Food Canada.

Hydrology
Did you know that Canada receives more snow than any other country? Click on the topic links in this course guide for scientific information about snow, rain, ice, water, and more. A University of Regina website.

Soil Conservation Council of Canada
The Soil Conservation Council of Canada is the face and voice of soil conservation in Canada. Features online articles about soil science and related topics.

What is Permafrost?
This site is an extensive information source about the nature and location of permafrost regions in Canada. Check the menu at the left side of the page for additional maps and data. From the Geological Survey of Canada.

Glossary: Alberta Soils
A glosssary of terms related to soil conditions and home construction. A Government of Alberta website.

Glossary: Environment
A glossary of terms related to the environment, ecology, and geology. Check the rest of the site for additional information. From the Alberta Online Encyclopedia.

Glossary: Prime and Marginal Agricultural Soils and Landscapes
A bilingual glossary of terms commonly used in the classification of agricultural soils and landscapes. Check other sections of this site for additional information on this topic. From the Government of Ontario.

Canadian Agri-Food Policy Institute
Check out this website for information and reports about current issues impacting on the productivity and competitiveness of Canada's agri-food sector.

Soils of Canada
An extensive information source about the formation, characteristics and distribution of various soil types found in Canada. From the Department of Soil Science, University of Saskatchewan.

Tillage for soil fertility before fertilizers
An academic paper about the impact of intensive tillage on soil fertility and the growth and productivity of cereal and fodder crops. From the Agricultural Institute of Canada.