Agri-environmental indicator Measure of change either in the state of environmental resources used or affected by agriculture, or in the farming activities that affect the state of these resources.

Agrochemical Chemical used in crop production.

Agro-ecosystem Ecosystem under agricultural management; an open, dynamic system that is connected to other ecosystems through the transfer of energy and materials.

Alluvial plain Level or gently sloping, flat or undulating surface formed from material deposited on recent floodplains by running water.

Alkaline Having a high pH value (greater than 7); also basic; the opposite of acidic.

Alternative agriculture School of thought in agriculture that sees people as one component in a large ecological system in which their needs must balance the earth's ability to produce without depletion or degradation.

Amendment Substance, such as manure and compost, that is added to soil to make it more productive.

Aquifer Geological bed or stratum that is far-reaching and porous enough to yield a supply of groundwater to one or more large wells or springs.

Aridity Dryness.

Background level Concentration of a substance in soil due to natural processes alone, where there is no history of application of this substance.

Baseline data set First set of measurements made at a site.

Benchmark site Locale at which certain soil properties and processes can be measured in a standard way at regular intervals.

Biocide Natural pesticide.

Black soils Chernozemic soils characterized by a very dark surface, a brownish B horizon, and usually a calcareous C horizon.

Brown soils Chernozemic soils characterized by a brown surface, lighter brown B horizon, and usually a calcareous C horizon.

Brunisolic soils Order of soils that occur under a wide variety of climatic and vegetative conditions, all having Bm or Btj horizons.

Bulk density Mass of dry soil per unit bulk volume.

Carbon cycle Route by which carbon is fixed by photosynthesis, added to soil as plant and animal remains, then released from soil through decomposition and mineralization.

Capillary zone Zone through which water is drawn from a water table toward the soil surface by capillary action.

Catch crop Usually a lower-value crop that is planted either between the rows of a main crop or in the fall after the main higher-value crop has been harvested to take up excess nutrients, such as nitrogen, in the soil.

Cation Positively charged ion.

Cation exchange capacity Capacity of a soil to retain and supply exchangeable cations, including nutrients.

Chemical rooting conditions Chemical characteristics of soil that control root growth.

Chernozemic soils Order of soils developed under cool, subarid-to-subhumid grasslands, characterized by a mineral surface horizon darkened by accumulating organic matter.

Coarse-textured soil Soil, such as sand and sandy loam, composed of coarse particles; also light-textured soil.

Colluvium Mixed material deposited mainly by gravity at the base of slopes or cliffs.

Compost Organic residues, usually with soil added, that have been piled, mixed, moistened, and allowed to decompose; used as a soil amendment.

Computer simulation model Mathematical model, processed on a computer, that is used to describe various soil processes and to predict how these processes will change if certain variables are altered.

Conservation tillage Methods of tillage that maintain a cover of crop residues on the soil surface and either reduce the amount of tilling (reduced tillage or minimal tillage) or eliminate it altogether (no-till).

Contamination Presence of a substance in soil or water at a concentration above the safe limit.

Continuous cropping Growing crops every growing season (no fallow years).

Contour cultivation Cultivation along the contour of the land, rather than up-and down-slope.

Conventional tillage Practice of tilling the land to improve it for agricultural purposes; includes plowing and cultivating for seeding and for weed control.

Crop residue Plant material remaining after harvesting, including leaves, stalks, roots.

Crop rotation Growing at least two crop varieties in sequence, such as soybean-corn or alfalfa- alfalfa-wheat.

Cropland Total area on which field crops, fruits, vegetables, nursery products, and sod are grown.

Crop-tolerance testing Tests to detect a crop's ability to grow in a certain soil.

Crop yield Quality and quantity of a crop harvested.

Cropping intensity Share of farmland devoted to cultivation.

Cultivated land Land tilled and used to produce crops; includes land left fallow.

Dark Brown soils Chernozemic soils characterized by a dark brown surface, a lighter brownish B horizon, and usually a calcareous C horizon.

Dark Gray soils Chernozemic soils characterized by a dark gray surface, a brownish B horizon, and usually a calcareous C horizon.

Database Collection of data.

Decomposition Process by which organic and inorganic residues (plant and animal remains) are broken down.

Discharge area Area in which groundwater comes to the soil surface.

Dissipation capacity Soil's ability to adsorb, or hang on to, and degrade chemical compounds.

Diversion Rerouting of part of or all the water in a strem to a different course by means of small earth dikes and dams.

Ecozone Area having distinct climate, vegetation, geology, and soils.

Effluent Liquid waste discharged by industries and other producers into sewage systems and waterways.

Environmental buffer Soil serving to relieve stress on other parts of the environment, such as by detoxifying chemical contaminants.

Erodibility Measure of a soil's susceptibility to erosion.

Erosion, soil Movement of soil from one location to another mainly by wind and water, and also by tillage.

Erosion control Methods used to reduce soil losses resulting from erosion.

Extended rotation Cropping sequence that is lengthened by adding additional crop varieties to the sequence.

Farm stewardship Orderly management of a farm, including responsibility for efficient use of natural resources and care for the environment.

Farming system Overall plan to manage cropping and soils that combines a variety of management practices.

Farmland All land for crops, grazing and pasture, summerfallow, buildings and barnyards, bush, slough, and marshes.

Fertility, soil Measure of the amount of nutrients in the soil available for plant growth.

Fertilization Application of plant nutrients to the soil in the form of commercial fertilizers, animal manure, green manure, and other amendments.

Fines Very small particles in soil; silt and clay fraction.

Fine-textured soils Soils, such as clay and clay loam, composed of small particles; also heavy-textured soil.

Fluvial Relating to flowing water.

Forage Crops, such as alfalfa, that are either grazed or cut for animal feed.

Friability Describes the degree to which a soil can be crumbled.

Gleysolic soils Order of soils developed under wet conditions and characterized by reduced iron and other elements, gray colors, and prominent mottling.

Grassed waterway Grassed strip of land that serves as a channel for runoff; a method of controlling erosion.

Gray soils Luvisolic soils characterized by a light-coloured surface, a brownish B horizon, and usually a calcareous C horizon.

Green manure Any plant material that is plowed into the soil while still green to serve as a natural fertilizer or amendment.

Groundwater Subsurface water, the upper surface of which forms the

water table in geological materials such as soils, sand and gravel deposits, and bedrock formations; it is free to move by gravity.

Groundwater discharge Groundwater that comes up to the surface.

Growing degree days Measure of heat energy available for crop production.

Gully Channel cut into the soil surface by severe but intemittent water erosion and deep enough to interfere with tillage operations.

GUS value Groundwater ubiquity score (GUS) determined from how easily a pesticide is carried into the soil by downward-percolating water and from how fast it is broken down into harmless by-products by soil microorganisms and chemical reactions.

Half-life Time taken for one-half the amount of a chemical material or soil property to be degraded, transformed, or eliminated.

Hardpan Hardened soil layer at or beneath the surface, having greatly reduced porosity.

Heavy metals Metal elements, such as arsenic, cadmium, chromium, cobalt, copper, lead, mercury, molybdenum, nickel, selenium, and zinc, which are known to contaminate some soils.

Horizon See soil horizon.

Hummocky Uneven, hilly.

Humus Well-decomposed organic portion of the soil forming a dark brown, porous, spongy material wich a pleasant, earthy smell.

Hydraulic conductivity Describes the ability of soil to transmit water through soil pores; expresses permeability.

Hydrologic Relating to water.

Hydrologic cycle Route by which water passes naturally from water vapour in the atmosphere through precipitation onto land or water and back into the atmosphere by means of evaporation and transpiration; also water cycle.

Improved cropland Sum of cropland, summerfallow, and improved pasture.

Improved pasture Area improved by seeding, draining, irrigating, fertilizing, brush or weed control, not including areas where hay, silage, or seeds are harvested.

Index of inherent soil quality (ISQ) Measure to asses inherent soil quality based on broad-scale soil, landscape, and climatic information.

Index of soil quality susceptibility (SQS) Identifies agricultural areas that are at risk of declining soil quality because of various land use and management practices.

Indicator Factor indicating or helping to define the state of a large system.

Inherent erosion risk Risk of erosion on bare soil.

Inherent soil quality Natural quality of a soil as affected by parent materials and the way in which the soil developed.

Inorganic contaminant Soil contaminant that does not contain carbon, such as heavy metals.

Integrated pest management (IPM) Control of pests using a combination of crop rotations, cultivation, and biological and chemical pest controls.

Interseeding Companion planting; seeding a secondary crop along with the primary crop to provide soil cover after the primary crop is harvested; also underseeding.

Irrigation Artificial watering of land using water channels, pipes, or sprayers.

Lacustrine Relating to lakes.

Land use Way in which land is used, such as for pasture, orchards, and producing field crops.

Leachable Percolates easily down through the soil profile; refers to soluble substances.

Leaching Removal of materials in solution by water percolating through the soil profile.

Luvisolic soils Order of soils developed under forest in a moderate-to-cool climate, in which silicate clay removed from part of the A horizon has accumulated in part of the B horizon.

Macronutrient One of several chemical elements needed in large amounts for proper growth and development of plants (carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur); compare micronutrient.

Macroporosity Volume of large pores in the soil.

Marine Relating to the sea.

Methemoglobinemia State of oxygen starvation produced, especially in babies, when nitrite is absorbed into the bloodstream from the digestive tract; it impairs the ability of hemoglobin to transport oxygen.

Method detection limit (MDL) Smallest concentration of a substance that can be measured accurately by a certain analytical method.

Microbial oxidation Process in which soil microorganisms "burn up" organic matter in the soil during their normal metabolism.

Microorganisms Microscopic plants and animals present in the soil and active in decomposition.

Micronutrient One of several chemical elements (trace elements) needed in small amounts for proper growth and development of plants (iron, manganese, molybdenum, boron, copper, zinc, chlorine); compare macronutrient.

Mineralization Conversion of an organic to an inorganic substance as a result of microbial decomposition.

Mixed farm Farm that grows food or cash crops, feed crops, and livestock.

Monoculture Cultivation of a single plant species over a wide area for many years.

Monoculture row-cropping Cultivation of only one type of row crop for many years.

Morainal Relating to material deposited by glacial ice.

Mottling Mixed gray and orange colouration arising from reduced iron effects.

Nonlimiting water range Measure of the amount of water in soil that is available to plants.

Nitrate Predominant form of dissolved nitrogen in soil and groundwater and the principal source of nitrogen for higher plants.

No-till Tillage practice involving direct seeding, which does not break the soil surface.

Nonpoint-source entry Entry of agrochemicals into groundwater over a large land area, usually by leaching through the soil profile.

Nonrenewable resources Natural resources that cannot be replaced on a human time-scale once they have been used up (such as fossil fuels).

Nutrient retention Holding onto nutrients.

Organic contaminant Soil contaminant that contains carbon.

Organic matter Decomposed plant and animal residues.

Organic soil Soil containing a high level of organic matter.

Organic gradient Difference in salt concentrations between two solutions that controls the movement of water. Water moves from the solution with a lower concentration to that with a higher concentration of salt.

Pan Layer in the soil that is strongly compacted, hardened, or high in clay content.

Pedestal Column of soil supporting stones and plant debris; evidence of water erosion.

Penetrometer Instrument used for measuring soil strength by penetrating with a small cone.

Permanent crop cover Perennial crop, such as a forage, that protects the soil throughout the year.

Permeability Describes the ease with which gases, such as air, or fluids, such as water, can pass through a soil.

Pest Organism that is a nuisance to humans or injures crops and animals upon which people depend for food, fibre, and shelter.

Pesticide Chemical that kills or controls pests; includes herbicide, insecticide, fungicide, nematocide, rodenticide, and miticide.

Physical rooting conditions Physical characteristics, such as waterholding capacity and porosity, that control root growth.

Plastic limit Soil water content at which the soil changes from a semisolid to a plastic state.

Podzolic soils Order of soils formed under coniferous forests, generally from coarse parent materials, and containing a B horizon high in iron and aluminum.

Point-source entry Localized entry of agrochemicals into drinking water, such as by accidental spills and manure leakage into domestic wells.

Policy Principles and courses of action adopted by government to fulfil certain objectives, such as sustainable agriculture.

Pore space Space in a soil not occupied by soil particles.

Recharge area Place where water percolates through the soil into the groundwater.

Residue management Maintaining a cover of crop residues on the soil surface.

Rill Small water channel on the soil surface, caused by water erosion.

Root rot Plant disease characterized by decay on the roots.

Runoff Portion of the total precipitation that enters surface streams rather than infiltrating the soil.

Safe limit Concentration of a substance, such as bacteria, pesticides, or nitrate, in drinking water above which the substance may pose a risk to human or animal health.

Saline seep Intermittent or continuous saline discharge at or near the soil surface under dryland conditions, which reduces or eliminates crop growth.

Salinity Amount of soluble salts in a soil.

Salinity risk index Measure of the change that an area has a certain level of salinity.

Salinization Natural process by which salts accumulate in the soil.

Sediment Soil particles that are moved and deposited by wind, water, or gravity.

Seedbed Soil prepared for seeding.

Seed-drilling Seeding by means of an implement that plants seeds in holes or furrows and covers them with soil.

Sewage sludge Solid and semisolid waste resulting from the treatment of domestic and industrial effluents that are released into sewers.

Sheet erosion Removal of a fairly uniform layer of soil from the land surface by runoff water.

Shelterbelt Line of trees or bushes planted at the border of a field to break the force of the wind; also windbreak.

Sludge loading Maximum amount of sewage sludge that can be safely applied to soil.

Soil archive Collection of soil samples.

Soil compaction Pressing together of soil particles, reducing the pore space between them.

Soil contaminant Chemical substance present in the soil above safe limits.

Soil cover Vegetation, including crops, and crop residues left on the soil surface.

Soil degradation General process by which soil declines in quality and is thus made less fit for a specific purpose, such as crop production.

Soil health Soil's fitness to support crop growth without resulting in soil degradation or otherwise harming the environment; also soil quality.

Soil horizon Distinct layer of soil in the soil profile; primary horizons usually labelled A, B, or C.

Soil organic matter Constituent of soil that includes plant and animal remains in various stages of decomposition, cells and tissues of soil organisms, and substances produced by the soil microbes.

Soil pores Spaces between soil particles.

Soil porosity Amount of space in a soil not occupied by solid particles.

Soil profile Vertical section of a soil that displays all the soil horizons.

Soil quality Soil's fitness to support crop growth without resulting in soil degradation or otherwise harming the environment; also soil health.

Soil quality index Measure of a soil's health at one point in time; a "report card" of soil health.

Soil quality indicator Property, function, or condition of soil that is useful in describing soil quality.

Soil structure Physical properties of a soil relating to the arrangement and stability of soil particles and pores.

Soil texture Relative proportions of sand, silt, and clay in a soil.

Splash erosion Displacement of soil by falling droplets of water.

Strip-cropping Alternating tilled crops in narrow strips across a long slope.

Subsoil Layers of soil found below the original level of plowing between the topsoil and parent material.

Subsurface drainage Artificial drainage systems, such as tiles, installed below the soil surface to relieve wet soil conditions.

Summerfallow Land that is not cropped for at least 1 year.

Surface relief Elevations and depressions on the land surface.

Surface water Water occurring on the surface of the land, such as streams, rivers, ponds, lakes, and oceans.

Sustainable agriculture Way of farming that maintains the land's ability to produce over time.

Terrace Steplike surface that breaks the continuity of a slope.

Threshold values Points at which a change in soil quality is likely to occur.

Tillage Mechanical preparation of the soil for seeding, for fallow, or for weed control.

Tillage erosion Displacement of soil by the action of tillage.

Tilth Physical condition of the soil as it relates to ease of tillage and fitness as a seedbed.

Toxic Poisonous to plants, animals, or humans.

Transfer technology Convey useful scientific and technological findings to user groups.

Water contaminant Substance in water at a concentration above the safe limit, entering the surface water through runoff or the groundwater through leaching.

Water table Upper surface of the groundwater, found at a depth where the pressure in the water equals atmospheric pressure.

Winter cover-cropping Maintaining soil cover throughout the nongrowing season by planting a cover crop during the fall.


Date Modified: 2006-08-14		Important Notices
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