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About the origin of this glossary
Other glossaries
Abrasion: The physical weathering of a
rock surface by running water, glaciers, or wind laden with fine particles.
See: VENTIFACT.
Absorption: The physical uptake of water
and/or ions by a substance. For example, soils absorb water. See also: ADSORPTION
Accelerated Erosion: An increased
rate of erosion caused by humans.
Accessory Minerals: Minerals occuring
in small quantities in a rock whose presence or absence does not affect
the true nature of the rock.
Accumulation: The build-up or increase
of one or more constituents in the soil at a given position as a result
of translocation. The build-up may be a residue due to the translocation
of material out of the horizon or may be due to an addition of material.
Usually refers to soluble substances and clay particles.
Acicular: Needle shaped.
Acid Rock: An igneous rock that contains
more than 60 per cent silica and free quartz.
Acid Soil: A soil with a pH <6.5.
Acidity: The hydrogen ion activity in the soil
solution expressed as a pH value.
Actinomycetes: Family of microorganisms
belonging to a group intermediary between bacteria and molds (fungi), mainly
resembling the latter because they usually produce branched mycelium; a
form of filamentous, branching bacteria.
Adsorption: The attachment of a particle,
ion or molecule to a surface. Calcium is adsorbed onto the surface of clay
or humus. See also: ABSORPTION
Adsorption Complex: The various
substances in the soil that are capable of adsorption, these are mainly
clay or humus
Aeolian Deposits: Fine sediments transported
and deposited by wind; they include loess, dunes, desert sand, and some
volcanic ash.
Aeolian: Pertaining to wind action.
Aerated Static Pile: Composting
system using controlled aeration from a series of perforated pipes running
underneath each pile and connected to a pump that draws or blows air through
the piles.
Aeration: The process by which atmospheric
air enters the soil. The rate and amount of aeration depends on the size
and continuity of the pore spaces and the degree of water logging.
Aerial Photograph: A photograph of
the Earth's surface taken from an aeroplane or some other type of airborne
equipment.
Aerobic: Conditions having a continuous supply
of molecular oxygen. Compost: composting environment characterized by bacteria
active in the presence of oxygen (aerobes); generates more heat and is a
faster process than anaerobic composting. Aerobic temperatures may reach
over 140°F - high enough to destroy pathogens, weed seeds, and fly ova;
creates no excessive unpleasant odors; the most rapid composting process
occurs with enclosed aerobic systems. See also: ANAEROBIC
Aerobic Organisms: Organisms living
or becoming active in the presence of molecular oxygen.
AFP: Air filled porosity; the air capacity of a
compost.
Aggregates: Discrete clusters of particles
formed naturally of artificially and including such particles as crumbs,
granules, clods, faecal pellets, fragments of faecal pellets, and concretions.
Aggregation: The process by which particles
coalesce to form aggregates.
Agricultural Waste: Waste materials
produced from the raising of plants and animals, including manures, bedding,
plant stalks, hulls, leaves, and vegetable matter.
Agronomy: That part of agriculture devoted
to the production of crops and soil management; the scientific utilization
of agricultural land.
Air Classification: The separation
of mixed waste materials using a moving stream of air; light wastes are
carried upward while heavy components drop out of the stream.
Algae: Unicellular or multicellular plants containing
chlorophyll and which are aquatic or occur in damp situations and include
most seaweeds.
Alkaline Soil: A soil with pH >7.3
Allelopathy: The suppression of growth
of one plant species by another due to the release of toxic substances.
Alluvial Pan or
Alluvial Cone: Sediments deposited in a characteristic fan or cone shape
by a mountain stream as it flows on to a plain or flat open valley.
Alluvial Plain: A flat area built up
of alluvium.
Alluvial Soil: A general term for those
soils developed on a fairly recent alluvium.
Alluvium: A sediment deposited by streams
and varying widely in particle size. The stones and boulders when present
are round or sub-rounded. Some of the most fertile soils are derived from
alluvium of medium or fine texture.
Amino Acid: An organic compound containing
both the amino(NH2) and carboxyl (COOH) groups. Amino acid molecules combine
to form proteins, therefore they are a fundamental constituent of living
matter. They are synthesized by autotrophic organisms, principally green
plants.
Ammonia Fixation: Adsorption of ammonium
ions by clay minerals, rendering them insoluble and non-exchangeable.
Ammonification: The production of ammonia
by microorganisms through the decomposition of organic matter.
Anaerobic Organisms: Organisms
that live in an environment without molecular oxygen.
Anaerobic: Conditions that are free of molecular
oxygen. In soils this is usually caused by excessive wetness. Compost: composting
environment characterized by bacteria active in the absence of oxygen (anaerobes).
In anaerobic composting, the microflora obtain oxygen from the waste; peak
temperatures may reach 100–130°F; digestion requires more time,
foul odors are created and pathogens may survive. See also: AEROBIC
Anion Exchange Capacity: The
total amount of anions that a soil can adsorb, usually expressed as milligram
equivalents per kg of soil.
Anion: An ion having a negative charge.
Anisotropic: 1. General: possessing different
physical properties in different directions; 2. General: having physical
properties that depend on direction; 3. Minerals or parts of soils: alternately
bright and dark between crossed polars when the microscope stage is rotated.
The bright position is due to the formation of interference colors. See:
INTERFERENCE COLORS.
Annelid: Red blooded worm such as an earthworm.
Annual Plant: A plant that completes its
life cycle within one year.
Arid: A term applied to a region or climate in
which precipitation is too low to support crop production.
Arthropod: A member of the phylum arthropoda,
which is the largest in the animal kingdom. It includes insects, spiders,
centipedes, crabs, etc.
Aspect: The compass direction of a slope.
Aureole: Halo or ring around a feature.
Autotrophic Organisms: Organisms
that utilize carbon dioxide as a source of carbon and obtain their energy
from the sun or by oxidizing inorganic substances such as sulphur, hydrogen,
ammonium, and nitrate salts. The former include the higher plants and algae
and the latter various bacteria. See: HETEROTROPHIC
ORGANISMS
Available Elements: The elements
in the soil solution that can readily be taken up by plant roots.
Available Nutrients: See: AVAILABLE
ELEMENTS
Available Water: That part of the water
in the soil that can be taken up by plant roots.
Available Water Capacity:
The weight percentage of water which a soil can store in a form available
to plants. It is equal to the moisture content at field capacity minus that
at the wilting point.
Bacteria: Unicellular or multicellular
microscopic organisms. They occur everywhere and in very large numbers in
favorable habitats such as soil and sour milk where they number many millions
per gram.
Bar: 10 to the power of 5 Pascal or 10 to the power
of 5(Nm to the power of -2).
Basalt: A fine grained igneous rock forming
lava flows or minor intrusions. It is composed of plagioclase, augite, and
magnetite; olivine may be present.
Base Saturation: The extent to which
the exchange sites of a material are occupied by exchangeable basic cations;
expressed as a percent of the cation exchange capacity.
Basic Rock: An igneous rock that contains
less than 55% silica.
Batch Composting: All material is
processed at the same time, without introducing new feedstock once composting
has begun; windrow systems are batch systems. See also: CONTINUOUS-FLOW
Bedrock: The solid rock at the surface of the
earth or at some depth beneath the soil and superficial deposits.
Bench Scale Reactor: Laboratory
system to model the composting process, usually using water baths to mimic
large pile conditions.
Biennial: A plant that completes its life
cycle in two years.
Bioassay: A laboratory assay (test) using
a biological test organism.
Bioavailable: Available for biological
uptake.
Biodegradability: The potential of
an organic component for conversion into simpler structures by enzymatic
activity.
Biogenic Waste: (Germany) The separated
organic fraction of household waste; consists of yard and food waste.
Biological Oxygen
Demand (BOD): The amount of oxygen used in the biochemical oxidation
of organic matter; an indication of compost maturity and a tool for studying
the composting process.
Biomass: a) The weight of a given organism
in a volume of soil that is one meter square at the surface and extending
down to the lower limit of the organism's penetration. b) The weight of
organisms in a given area or volume.
Birefringence: The numerical difference
in value between the highest and lowest refractive index of a mineral. This
is not synonymous with interference colors. See: INTERFERENCE
COLORS.
Biosolids: Primarily organic solid products
produced by the wastewater treatment process that can be benefically recycled.
Blocky: Many sided with angular or rounded corners,
used for describing peds.
Bog Iron Ore: A ferruginous deposit in
bogs and swamps formed by oxidizing algae, bacteria or the atmosphere on
iron in solution.
Boulder Clay: See: TILL.
B.S.: An abbreviation for Base Saturation.
Buffer: A substance that prevents a rapid change
in pH when acids or alkalis are added to the soil. These include clay, humus,
and carbonates.
Bulk Density: Mass per unit volume of
undisturbed soil, dried to constant weight at 105°C (221°F), usually
expressed as g/cc.
Bulking Agent: Material, usually carbonaceous
such as sawdust or woodchips, added to a compost system to maintain airflow
by preventing settlement and compaction of the waste.
Cadmium to Zinc Ratio (Cd:Zn Ratio):
Ratio of those two elements used to study heavy metal accumulation by animals.
Calcareous Soil: A soil that contains
enough calcium carbonate so that it effervesces when treated with hydrochloric
acid.
Calcification: Used by some to refer
to the processes of calcium carbonate accumulation.
Calcite: Crystalline calcium carbonate, CaCO3.
Crystalizes in the hexagonal system, the main types of crystals in soils
being dog-tooth, prismatic, nodular, fibrous granular, and compact.
Caliche: A layer or horizon cemented by the
deposition of calcium carbonate. It usually occurs within the soil but may
be at the surface due to erosion.
Capillarity: The quality of a soil that
allows moisture moves in any direction through the fine pore spaces and
as films around particles.
Capillary Fringe: The zone just above
the water-table that remains practically saturated with water.
Capillary Moisture: That amount
of water that is capable of movement after the soil has drained. It is held
by adhesion and surface tension as films around particles and in the finer
pore spaces.
Carbohydrates: Various kinds of sugars,
generally easily assimilated by bacteria.
Carbon to Nitrogen Ratio (C:N
Ratio): Ratio representing the quantity of carbon (C) in relation to
the quantity of nitrogen (N) in a soil or organic material; determines the
composting potential of a material and serves to indicate product quality.
Catena: A sequence of soils developed from similar
parent material under similar climatic conditions but whose characteristics
differ because of variations in relief and drainage.
Cation: An ion having a positive electrical
charge.
Cation Exchange: The exchange between
cations in solution and cations held on the exchange sites of minerals and
organic matter.
Cation Exchange
Capacity (CEC): The total potential of soils for adsorbing cations,
expressed in milligram equivalents per kg of soil. Determined values depend
somewhat on the method employed. Compost: A routine measure of the binding
potential of a soil; measures the soil's ability to remove negative ions
from metals and other compounds, allowing the ions to form insoluble compounds
and precipitate in the soil; determined by the amount of organic matter
and the proportion of clay to sand. The higher the CEC, the greater the
soil's ability to bind metals.
Cellulose: Carbon component of plants, not
easily digested by microorganisms.
Cemented: Massive and either hard or brittle
depending on the content of cementing substances such as calcium carbonate,
silica, oxides of iron and aluminum, or humus.
Chalk: The term refers to either (a) soft white
limestone which consists of very pure calcium carbonate and leaves little
residue when treated with hydrochloric acid, and sometimes consists largely
of the remains of foraminifera, echinoderms, molluscs, and other marine
organisms, or (b) The upper or final member of the cretaceous system.
Chamber: A relatively large circular or ovoid
pore with smooth walls and an outlet through channels or planar pores.
Channel: A tubular-shaped pore.
Chemical Oxygen
Demand (COD): A measure of the oxygen equivalent of that portion of
organic matter in a sample that is susceptible to oxidation by a strong
chemical oxidant; an important, rapidly measured parameter for stream and
industrial waste studies and for control of waste treatment plants.
Chlorosis: The formation of pale green or
yellow leaves in plants resulting in the failure of chlorophyll to develop.
It is often caused by a deficiency in an essential element.
Chroma: The relative purity of a color directly
related to the dominance of the determining wavelength; a quality of color
combining HUE and SATURATION.
Chronosequence: A sequence of soils
that changes gradually from one to the other with time.
Circularly Polarized Light:
This is produced by two */4 mica plates between crossed polars. One plate
is inserted in the 45 degree position in the slot of the microscope. The
second plate is inserted above the polarizer at right angles to the upper
mica plate. The effect is that all extinction phenomena of minerals disappear
and they remain bright in all positions of the stage. Only isotropic materials
and basal sections appear dark.
Clay: Either 1. Mineral material <2mm. 2. A
class of texture. 3. Silicate clay materials.
Clay Coating: See: COATING.
Clay Mineral: Crystalline or amorphous
mineral material, <2mm in diameter.
Clay Pan: A middle or lower horizon containing
significantly more clay than the horizon above. It is usually very dense
and has a sharp upper boundary. Clay pans generally impede drainage, are
usually plastic and sticky when wet and hard when dry.
Cleavage: The ability of a mineral or rock
to split along predetermined planes.
Climax Vegetation: A fully developed
plant community that is in equilibrium with its environment.
Clod: A mass of soil produced by disturbance.
Co-Composting: Composting process utilizing
carbon-rich organic material including leaves, yard waste, or mixed municipal
solid waste, in combination with a nitrogen-rich amendment such as sewage
sludge.
Coating: A layer of a substance completely
or partly covering a surface. Coatings are composed of a variety of substances
separately or in combination. They include clay coatings (clay skins), calcite
coatings, whole soil coatings, etc. Coatings may become incorporated into
the matrix or be fragmented
Coefficient
of Linear Extensibility (COLE): The ratio of the difference between
the moist and dry lengths of a clod to its dry length, (Lm-Ld)/Ld, where
Lm is the moist length at (1/3 atmospheres) and Ld is the air-dry length.
The measure correlates with the volume change of a soil upon wetting and
drying.
Colloid: The organic and inorganic material
with very fine particle size and therefore high surface area which usually
exhibits exchange properties.
Colluvium: Soil materials with or without
rock fragments that accumulate at the base of steep slopes by gravitational
action.
Compaction: Increase in bulk density due
to mechanical forces such as tractor wheels.
Composite Structure: Any combination
of different types of peds.
Compost: Plant and animal residues that are
arranged into piles and allowed to decompose, sometimes with soil or mineral
fertilizers being added. The stabilized product of composting, which is
beneficial to plant growth; it has undergone an initial, rapid stage of
decomposition and is in the process of humification.
Composting: The biodegradation, usually
aerobic and thermophilic, that: involves a heterogeneous organic substrate
in the solid state; evolves by passing through a thermophilic stage with
a temporary release of phytotoxins; results in the production of carbon
dioxide, water, minerals and stabilized organic matter.
Composting, Municipal: Solid waste
management method whereby the organic component of the solid waste stream
is biologically decomposed under controlled conditions; an aerobic process
in which waste organic materials are ground or shredded and then decomposed
to humus in windrow piles or in mechanical digesters, drums, or similar
enclosures; results in volume and odor reduction, waste stabilization, destruction
of pathogens, larvae and weed seeds; the final product is sufficiently stable
for storage and land application without adverse environmental effects.
Compound Structure: Large peds such
as prisms and columns that are themselves composed of smaller incomplete
peds.
Concretion: Small, hard local concentrations
of material such as calcite, gypsum, iron oxide, or aluminum oxide. Usually
spherical or subspherical but may be irregular in shape.
Condensate: Moisture in the air that is
pulled through a compost pile.
Conductivity: A measure of the soluble
salts in the soil; used as an overall indicator of the level of macro- and
micronutrients in the soil.
Conglomerate: A sedimentary rock composed
mainly of rounded boulders.
Coniferous Forest: A forest consisting
of predominantly cone-bearing trees with needle shaped leaves which are
usually evergreen, but some are deciduous, for example the larch forests
(Larix dehurica) of central Siberia. Their greatest extent is in the wide
belt across northern Canada and northern Eurasia. Coniferous forests produce
soft wood which has a large number of industrial applications including
paper making.
Consistence: The resistance of the soil
to deformation or rupture as determined by the degree of cohesion or adhesion
of the soil particles to each other.
Consolidated: A term that usually refers
to compacted or cemented rocks.
Contaminant: Foreign material lending impurity
to a primary material; physical contaminants of compost include glass and
plastic, chemical contaminants include heavy metals and toxic organic compounds.
Continuous-flow: A system of composting
in which material is continuously added to the composting process and the
end product is continuously removed; often used for large operations. See
also: BATCH COMPOSTING
Continuously Anaerobic (very poorly
drained): A horizon that is saturated with water throughout the year,
it is blue, olive or grey.
Controlled Dynamic System:
Compost piles which receive forced aeration and periodic turning. See also:
AERATED STATIC PILE.
Creep: Slow movement of masses of soil down slopes
that are usually steep. The process takes place in response to gravity facilitated
by saturation with water.
Crotovina: An animal burrow which has been
filled with material from another horizon.
Croute Calcaire: A synonym for caliche.
Crust: A surface layer of soils that becomes
harder than the underlying horizon.
Curing: A late stage of composting, after much
of the readily metabolized material has been decomposed, which provides
additional stabilization and allows further decomposition of cellulose and
lignin.
Cutans: Coatings or deposits of material on
the surface of peds, stones, etc. A common type is the clay cutan caused
by translocation and deposition of clay particles on ped surfaces.
Deciduous Forest: A forest composed
of trees that shed their leaves at some season of the year. In tropical
areas the trees lose their leaves during the hot season in order to conserve
moisture. Deciduous trees of the cool areas shed their leaves during the
autumn to protect themselves against the cold and frost of winter. Deciduous
forests produce valuable hardwood timber such as teak and mahogany from
the tropics, oak and beech from the cooler areas.
Decomposition: Conversion of organic
matter as a result of microbial and/or enzymatic interactions; initial stage
in the degradation of an organic substrate, characterized by processes of
destabilization of the pre-existing structure.
Deficiency Symptom: A result, including
slow plant growth, chlorosis, or necrosis, caused by the lack of a plant
essential element.
Deflation: Preferential removal of fine soil
particles from the surface soil by wind. See: DESERT PAVEMENT.
Deficiency: The lack of an adequate amount
of a plant nutrient.
Deflocculate: To separate disperse particles
of clay dimensions from a flocculated condition.
Delta: A roughly triangular area at the mouth
of a river composed of river transported sediment.
Denitrification: The biological reduction
of nitrogen to ammonia, molecular nitrogen, or oxides of nitrogen, resulting
in the loss of nitrogen into the atmosphere and therefore undesirable in
agriculture.
Deposit: Material placed in a new position
by the activity of humans or natural processes such as wind, water, ice,
or gravity.
Desert Crust: A hard surface layer in
desert regions containing calcium carbonate, gypsum, or other cementing
materials.
Desert Pavement: A layer of gravel
or stones remaining on the surface of the ground in deserts after the removal
of fine material by wind. See: DEFLATION and HAMADA.
Desert Varnish: A dark glossy sheen
or coating on gravel or stones in arid regions, probably composed of compounds
of iron and manganese.
Devonian: A period of geological time extending
from 320–280 million years before the present.
Dewatered Sewage Sludge: Sewage
sludge with a total solids content of 6% or greater that can be transported
and handled as a solid material; usually done by belt press, screw press,
vacuum filtration or centrifuge.
Diatoms: Algae that possess a siliceous cell
wall which remains preserved after the death of the organisms. They are
abundant in both fresh and salt water and in a variety of soils.
Digester: An enclosed composting system with
a device to mix and aerate the waste materials.
Digestion: Composting: The most active stage
of the composting process; carried out in open windrows or in enclosures;
the objective is to create an environment in which microorganisms will rapidly
decompose the organic portion of the refuse.
Dispersion: The process whereby the structure
or aggregation of the soil is destroyed so that each particle is separate
and behaves as a unit.
Doline or Dolina: A closed depression in a karst
region often rounded or elliptical in shape, formed by the solution and
subsidence of the limestone near the surface. Sometimes at the bottom is
a sink hole into which surface water flows and disappears underground.
Domain: A bundle of clay particles that is only
visible in crossed polarized light.
Drift: A generic term for superficial deposits
including till (boulderclay), outwash gravel and sand, alluvium, solifluction
deposits, and loess.
Drum Composting System: Enclosed
cylindrical vessel which slowly rotates for a set period of time to break
up and decompose material.
Drumlin: A small hill, composed of glacial
drift with hog back outline, oval plan, and long atlas oriented in the direction
of ice movement. Drumlins usually occur in groups, forming what is known
as basket of eggs topography.
Dry Farming: A method of farming in arid
and semi-arid areas without using irrigation, the land being treated so
as to conserve moisture. The technique consists of cultivating a given area
in alternate years allowing moisture to be stored in the fallow year. Moisture
losses are reduced by producing a mulch and removing weeds. In Siberia,
where melting snow provides much of the moisture for spring crops, the soil
is ploughed in the autumn providing furrows in which snow can collect, preventing
it from being blown away and evaporated by strong winds. Usually alternate
narrow strips are cultivated in an attempt to reduce erosion in the fallow
year. Dry farming methods are employed in the drier regions of India, USSR,
Canada, and Austria.
Dunes, Sand Dunes: Ridges or small hills of sand
which have been piled up by wind action on sea coasts, in deserts, and elsewhere.
Barkhans are isolated dunes with characteristic crescentic forms.
Dynamic Pile System: Compost piles
which receive forced aeration and are not turned. See also: AERATED
STATIC PILE.
Ecology: The study of interrelationships
between individual organisms, and between organisms and their environments.
Ecosystem: A group of organisms interacting
among themselves and with their environment.
Edaphic: (1) Of or pertaining to the soil.
(2) Influenced by soil factors.
Edaphology: The study of the relationships
between soil and soil including the use of the land by humans.
Efflorescence: The accumulation of dissolved
substance (usually simple salts) at a surface due to evaporation.
Eluvial Horizon: A horizon from which
material has been removed either in solution or suspension.
Eluviation: Removal of material from the
upper horizon in solution or suspension.
Enclosed System: See: IN-VESSEL COMPOSTING.
Equatorial
Forest or Tropical Rain Forest: A dense, luxuriant, evergreen forest
of hot, wet equatorial regions containing many trees of tremendous heights,
largely covered with lianas and epiphytes. Individual species of trees are
infrequent but they include such valuable tropical hardwoods such as mahogany,
ebony and rubber. Typical equatorial forests occur in the Congo Basin, the
Amazon Basin, and in southeastern Asia.
Erosion Pavement: A layer of gravel
or stones left on the surface of the ground after the removal of the fine
particles by erosion.
Erosion: The removal of material from the surface
of the land by weathering, running water, moving ice, wind, and mass movement.
Esker: A long narrow ridge, chiefly of gravel
and sand formed by a melting glacier or ice sheet.
Essential Elements: The elements
C, H, O, P, K, N, S, Ca, Mg, K, B, Mn, Cu, Zn, Mo, Cl, Co, Si, and F. These
must be taken up and utilized in sufficent quantities for plants to complete
their life cycles.
Eutrophic: Containing an optimum concentration
of plant nutrients.
Evapotranspiration: The combined
processes of evaporation and transpiration.
Excessively Aerobic: A horizon
which is usually too dry to support adequate plant growth.
Excessively Drained: A soil that
loses water very rapidly because of rapid percolation.
Exchangeable Cation: A cation such
as calcium that is adsorbed onto a surface, usually clay or humus, and is
capable of being easily replaced by another cation such as potassium. Exchangeable
cations are readily available to plants.
Exfoliation: A weathering process during
which thin layers of rock peel off from the surface. This is caused by the
heating of the rock surface during the day and cooling at night leading
to alternate expansion and contraction. This process is sometimes termed
"onion skin weathering".
Extinction Angle: The angle at which
a crystal goes black in crossed polarized light.
Extinction: The position at which a crystal
goes black in crossed polarized light.
Fabric: See: SOIL
FABRIC.
Facultative Aerobic Organisms:
Organisms capable of growing under both aerobic and anaerobic conditions
Faecal Material: The various types
of faeces or excrement produced by soil fauna.
Fallow: Leaving the land uncropped for a period
of time. This may be to accumulate moisture, improve structure, or induce
mineralization of a nutrient.
Family: One of the categories in soil classification
intermediate between the great soil group and the soil series.
Fen Peat: Peat that is neutral to alkaline
due to the presence of calcium carbonate.
Ferralitisation: Used by some to refer
to the process of formation of ferralitic soils. This term is not specific
and should not be used.
Fertilizer: A material that is added to
the soil to supply one or more plant nutrients in a readily available form.
Field
Capacity or Field Moisture Capacity: The total amount of water remaining
in a freely drained soil after the excess has flowed into the underlying
unsaturated soil. It is expressed as a percentage of the oven-dry soil.
Fine Material: Soil material in thin
sections composed of particles less than 2mm which are difficult or impossible
to resolve with the petrological microscope.
Fine Texture: Containing >35 percent
clay.
Finishing: Post-processing; screening, grinding,
or a combination of similar processes to remove plastics, glass, and metals
remaining after composting.
Flood Plain: The land adjacent to a stream,
built of alluvium and subject to repeated flooding.
Fluvent: Floodplain soils, characterized by
buried horizons and irregularly decreasing amounts of organic matter with
depth.
Fluvio-Glacial: See: GLACIO-FLUVIAL
DEPOSITS.
Food Waste: Residual food from residences,
institutions, or commercial facilities; unused portions of fruit, animal,
or vegetable material resulting from food production.
Folist Gleization: A process in saturated
or nearly saturated soils which involves the reduction of iron, its segregation
into mottles and concretions, or its removal by leaching from the gleyed
horizon.
Fragment: A small mass of soil produced by
a disturbance.
Fragipan: Brittle subsurface restricting soil
horizon, usually loamy textured and weakly cemented.
Freely Drained: A soil that allows water
to percolate freely.
Friable: A term applied to soils that when either
wet or dry crumble easily between the fingers.
Fulvic Acid: The mixture of organic substances
remaining in solution upon acidification of a dilute alkali extract of soil.
Fungi: Simple plants that lack chlorophyll and
are composed of cellular filamentous growth known as hyphae. Many fungi,
but their fruiting bodies, viz. mushrooms and puffballs are quite large.
In composting: Saprophytic or parasitic multinucleate organisms with branching
filaments called hyphae, forming a mass called a mycelium; fungi bring about
cellulolysis and humification of the substrate during stabilization.
Gastropod: A member of the Gastropoda
class of molluscs which includes snails and slugs.
Geomorphology: The study of the origin
of physical features of the Earth, as they are related to geological structure
and denudation.
Gilgai: A distinctive microrelief of knolls
and basins that develop on clay soils that exhibit a considerable amount
of expansion and contraction in response to wetting and drying.
Glacial Drift: Materials transported
by glaciers and deposited directly from the ice or from the meltwater.
Glacier: A large mass of ice that moves slowly
over the surface of the ground or down a valley. They originate in snowfields
and terminate at lower elevations in a warmer environment where they melt.
Glacio-Fluvial Deposits: Material
deposited by meltwaters coming from a glacier. These deposits are variously
stratified and may form outwash plains, deltas, kames, eskers, and kame
terraces. See: GLACIAL DRIFT and TILL.
Gleisation: See: GLEYING.
Gleying: The reduction of iron in an anaerobic
environment leading to the formation of grey or blue colors.
Gleyed: A soil condition resulting from gleization
which is manifested by the presence of neutral grey, bluish, or greenish
colors through the soil matrix or in mottles (spots or streaks) among other
colors.
Granite: An igneous rock that contains quartz,
feldspar, and varying amounts of biotite and muscovite.
Gravitational Water: The water
that flows freely through soils in response to gravity.
Great Soil Group: One of the Categories
in soil classification.
Green Waste: That portion of the municipal
waste stream consisting of grass clippings, tree trimmings, and other vegetative
matter.
Groundwater-Table: The upper limit
of the groundwater.
Growing Season: The portion of the year
when soil temperatures are above biologic zero 41°F (4°C) as defined
by Soil Taxonomy.
Gully: A shallow steep-sided channel that may
occur naturally or be formed by accelerated erosion.
Gully Erosion: A form of catastrophic
erosion that forms gullies.
Gyttja: Peat consisting of faecal material,
strongly decomposed plant remains, shells of diatoms, phytoliths, and fine
material particles. Usually forms in standing water.
Halomorphic Soil: A soil containing
a significant proportion of soluble salts.
Halophyte: A plant capable of growing in
salty soil; i.e. a salt tolerant plant.
Halophytic Vegetation: Vegetation
that tolerates or requires saline conditions.
Hamada: An accumulation of stones at the surface
of deserts, formed by the washing or blowing away of the finer material.
Hammermill: Machine using rotating or flailing
hammers to grind material as it falls through the machine or rests on a
stationary metal surface.
Hardpan: A horizon cemented with organic matter,
silica, sesquioxides, or calcium carbonate. Hardness or rigidity is maintained
when wet or dry and samples do not slake in water.
Heavy Metals: Trace elements regulated
because of their potential for human, plant, or animal toxicity, including
cadmium (Cd), copper (Cu), chromium (Cr), mercury (Hg), nickel (Ni), lead
(Pb), and Zinc (Zn).
Heavy Soil (Obsolete): A soil that has a
high content of clay and is difficult to cultivate.
Heterotrophic Organisms: Those
that derive their energy by decomposing organic compounds. See: AUTOTROPHIC ORGANISMS.
High Water Mark: A distinct mark made
on vegetation, buildings, or rocks that shows the extent of water rise.
Histosol: A soil order in the taxonomic system
that is composed of mucks and peats that have a high concentration of organic
materials in the surface soil or overlying rock.
Holocene Period: The period extending
from 10,000–0 years before the present.
Horizon: Relatively uniform materials that
extend laterally, continuously or discontinuously throughout the pedounit;
runs approximately parallel to the surface of the ground and differs from
the related horizons in many chemical, physical, and biological properties.
Hue: The dominant spectral color; one of the three
color variables. See: VALUE and SATURATION.
See also: CHROMA
Humic Acid: Usually refers to the mixture
of ill-defined dark organic substances precipitated upon acidification of
a dilute alkali extract of soil. Some workers use it to include only the
alcohol-insoluable portion of the precipitate. The main constituent of humus,
composed of proteins and lignins, dark brown to black in color.
Humification: The decomposition of organic
matter leading to the formation of humus. The microbial synthesis of three-dimensional
polymers of saccharides and phenols resembling gums and lignin; a process
of storing organic energy in compounds of high molecular weight which are
slowly degradable (10–100+ years).
Humin: Usually applied to that part of the organic
matter that remains after extraction with dilute alkali.
Humus: The well-decomposed, relatively stable
part of the organic matter found in aerobic soils. A complex aggregate of
amorphous substances, formed during the microbial decomposition or alteration
of plant and animal residues and products synthesized by soil organisms;
principal constituents are derivatives of lignins, proteins and cellulose.
Humus has a high capacity for base exchange (CEC), combining with inorganic
soil constituents, and for water absorption. Finished compost may be designated
by the general term humus.
Hydration: The process whereby a substance
takes up water.
Hydraulic Conductivity: The
rate at which water will move through soil in response to a given potential
gradient.
Hydric soil: A soil that is saturated with
water long enough during the plant growing season to become anaerobic. This
soil will usually be characterized by anaerobic soil zones and wetland vegetation.
Hydrologic Cycle: Disposal of precipitation
from the time it reaches the soil surface until it re-enters the atmosphere
by evapotranspiration to serve again as a source of precipitation.
Hydrolysis: In soils it is the process whereby
hydrogen ions are exchanged for cations such as sodium, potassium, calcium,
and magnesium.
Hydromorphic Soil: Soils developed
in the presence of excess water.
Hydromulching: An application method
using a water jet to spread a mulch emulsion on a land surface.
Hydrophytic Vegetation: Plants
that can exist in water that at least periodically is subject to anaerobic
conditions.
Hygroscopic Water: Water that is
adsorbed onto a surface from the atmosphere.
Igneous Rock: A rock formed by cooling
of molten magma including basalt and granite.
Illuvial Horizon: A horizon that receives
material in solution or suspension from some other part of the soil.
Illuviation: The precess of movement of
material from one horizon and its deposition in another horizon of the same
soil, usually from an upper horizon to a middle or lower horizon in the
pedounit. Movement can also take place laterally.
Immature Soil: Lacking a well developed
pedounit.
Immobilization: Conversion of an element
from its inorganic form to its organic form within microbial or plant tissues,
rendering it unavailable to other organisms or plants
Impeded Drainage: Restriction of the
downward movement of water by gravity.
Imperfectly drained: A soil that
shows a small amount of reduction of iron due to short periods of water-logging.
Impervious: Not easily penetrated by roots
or water.
In-Vessel Composting (also "Enclosed"
or "Mechanical"): A system using mechanized equipment to rapidly
decompose wastes in an enclosed area with controlled amounts of moisture
and oxygen.
Incomplete Structure: Aggregates
joined together by narrow necks.
Incubation Study: Study done in a
laboratory setting under controlled temperature and moisture conditions
Inerts: Non-biodegradable products contained
in wastes (glass, plastics, etc.)
Infiltration: The process whereby water
enters the soil through the surface.
Inocula: Preconditioned microorganisms or compost
products added to raw material to provide the appropriate microorganisms
for decomposition.
Inorganic: Substance in which carbon-to-carbon
bonds are absent; mineral matter.
Inselberg: (pl. inselberge) A steep sided
hill composed predominantly of hard rock and rising abruptly above a plain;
found mainly in tropical and subtropical areas.
Interference Colors: The colors
of the Newton scale that are formed when a birefringent mineral or some
plant material is examined between cross polarizers. See: BIREFRINGENCE.
Interglacial Period: A period of
relatively mild weather occuring between two glacial periods.
Intergrade: A soil which contains the properties
of two distinctive and genetically different soils.
Interstadial Period: A slightly
warmer phase during a glacial period.
Intrazonal Soils: One of the three
orders of the zonal system of soil classification. They have well developed
characteristics resulting from the dominant influence of a local factor
such as topography and parent material.
Isomorphous Replacement: The
replacement of one ion by another in the crystal lattice without changing
the structure of the mineral.
Isotropic: Not visible in cross polarized
light. See: ANISOTROPIC.
Karst Topography: An irregular
land surface in a limestone region. The principal features are depression
(e.g. dolines which sometimes contain thick soils which have been washed
off the rest of the surfaces leaving them bare and rocky.) Drainage is usually
by underground streams.
Krotovina: See: CROTOVINA.
Lacustrine Deposit: Materials
deposited by lake waters.
Lacustrine: Pertaining to lakes.
Land Clearing Debris: Yard waste
and prunings or stumps six inches or greater in diameter resulting from
land clearing operations.
Land Reclamation: The restoration
of productivity to lands made barren through processes such as erosion,
mining, or land clearing.
Landslide or Landslip: The movement down
the slope of a large mass of soil or rocks from a mountain or cliff. Often
occurs after a torrential rain which soaks into the soil making it heavier
and more mobile. Earthquakes and the undermining action of the sea are also
causative agents.
Laterisation: Used by some to refer to
the processes of formation of laterite or red and yellow tropical soils.
This term is not specific and should not be used.
Lattice Structure: The orderly arrangement
of atoms in crystalline material.
Leachate: Liquid which has percolated through
solid wastes and extracted dissolved and suspended materials; liquid that
drains from the compost mix.
Leaching: The washing out of material from
the soil, both in solution and suspension.
Light Soil: (obsolete) A soil which has
a course texture and is easily cultivated.
Lignin: The component of wood responsible for
its rigidity.
Lime: Compounds of calcium used to correct the
acidity of soils.
Lipids: A generic term for all fats, oils, and
related fatty compounds.
Litter: The freshly fallen plant material occuring
on the surface of the ground.
Loading Rate: Measure of application amount,
based on nutrients, trace metals, or total mass of material.
Lodging: The collapse of top heavy plants,
particularly grain crops, because of excess growth or beating by rain.
Loess: An aeolian deposit composed mainly of
silt which originated in arid regions from glacial outwash or from alluvium.
It is usually of yellowish brown color and has a widely varying calcium
carbonate content. In the USSR, loess is regarded as having been deposited
by water.
Lysimeter: Apparatus installed in the soil
for measuring percolation and leaching.
Macroelement: Elements such as nitrogen
that are needed in large amounts for plant growth. Nutritive elements needed
in large quantities to ensure normal plant development (N,P,K, S, Mg, Ca,
Fe).
Macronutrient: See: MACROELEMENT.
Macropores: Pores >100mm in diameter.
Mangrove Swamp: A dense jungle of mangrove
trees which have the special adaptation of extending from their branches
long arching roots which act as anchors and form an almost impenetrable
tangle. They occur in tropical and subtropical areas, particularly near
the mouths of rivers.
Manure: Animal excreta with or without a mixture
of bedding or litter.
Matrix: The fine material (generally <2mm)
forming a continuous phase and enclosing coarser material and/or pores.
Mature Compost: Compost that has been
cured to a stabilized state, characterized as rich in readily available
forms of plant nutrients, poor in phytotoxic acids and phenols, and low
in readily available carbon compounds.
Mature Soil: A well developed soil usually
with clearly defined horizonation.
Mechanical Composting: See: IN-VESSEL
COMPOSTING.
Meristem: The region of active cell-division
in plants. The cells so formed then become modified to form the various
tissues such as the epidermis and cortex.
Mesofauna: Small organisms such as worms
and insects.
Mesophilic Stage: A stage in the composting
process characterized by bacteria that are active in a moderate temperature
range of 20° to 45°C (68° to 113°F); it occurs later, after
the thermophilic stage and is associated
with a moderate decomposition rate.
Metabolism: Sum of the chemical reactions
within a cell or whole organism, including the energy-releasing breakdown
of molecules (catabolism), and the synthesis of complex molecules and new
protoplasm (anabolism).
Metamorphic Rock: A rock that has
been derived from other rocks by heat and pressure. The original rock may
have been igneous, sedimentary, or another metamorphic rock.
Microbe, Soil: A soil microorganism.
Microbial: Pertaining to microbes.
Microclimate: The climate of a very small
region.
Microelement: Those elements that are
essential for plant growth but are required only in very small amounts.
Nutritive elements needed in small quantities for healthy plant development;
trace elements (Mn, B, Cl, Zn, Cu, Mo).
Microfauna: Small animals only visible with
a microscope, including protozoa, nematodes, etc.
Microflora: The small plants that can only
be seen with a microscope; they include algae, fungi, bacteria, etc.
Micronutrient: See: MICROELEMENT.
Microorganisms: The members of the flora
and fauna that can only be seen with a microscope.
Micropores: Pores 5–30mm in diameter.
Microrelief: Small differences in relief
that have differences in elevation up to about 2 m.
Milliequivalent: A thousandth of an
equivalent weight.
Mineral Soil: A soil that is composed
predominantly of mineral material. See: ORGANIC
SOIL.
Mineral-N: Nitrogen in its inorganic form,
usually as nitrates or ammonium.
Mineralisation: The change of an element
in an organic form to an inorganic form by microorganisms.
Mites: Very small members of the arachnids, which
includes spiders; they occur in large numbers in many organic surface soils.
Mixed Waste Paper: Low-grade, potentially
compostable paper, including noncorrugated paperboard, paperback books,
telephone books, paper towels, and paper food containers.
Moder: A kind of decomposition and humus formation
which reproduces advanced but incomplete humification of the remains of
organisms due to good aeration.
Moisture Content: The mass of water
lost per unit dry mass when the material is dried at 103°C (217°F)
for eight hours or more. The minimum moisture content required for biological
activity is 12–15%; it generally becomes a limiting factor below 45
or 50%; expressed as a percentage, moisture content is water weight/wet
weight.
Mor: An accumulation of acid organic matter at
the soil surface beneath forest.
Moraine: Any type of constructional topographic
form consisting of till and resulting from glacial deposition.
Mottles: See: MOTTLING.
Mottling: Patches or spots of different colors
usually used for the color pattern developed due to partial anaerobism.
Muck: Highly decomposed organic wet soil.
Muckiness, classification: Highly decomposed
organic wet soil.
Mulch: A loose surface horizon that forms naturally
or may be produced by cultivation and consists of either inorganic or organic
materials. Any suitable protective layer of organic or inorganic material
applied or left on or near the soil surface as a temporary aid in stabilizing
the surface and improving soil microclimatic conditions for establishing
vegetation; mulch reduces erosion and water loss from the soil and can be
used to control weeds.
Mulching: The application of a layer of compost
to the surface of the soil, creating an interface that accepts water readily
yet resists moisture loss through evapotranspiration.
Mull: A crumbly intimate mixture of organic and
mineral material formed mainly by worms, particularly by earthworms.
Municipal Solid
Waste (MSW): residential and commercial solid waste generated within
a community.
Mushroom Compost: Cellulose-rich organic
matter, such as manure and straw, that has undergone the initial decomposition
stage of a controlled composting process; used by mushroom growers.
Mycorrhiza: Soil-borne fungi that invade
the roots of vascular plants and establish a symbiotic relationship; mycorrhiza
hyphae, filaments that extend from plant roots, increase the surface area
for nutrient and water absorption.
Necessary Nutrient: The elements
C, H, O, P, K, N, S, Ca, Mg, K, B, Mn, Cu, Zn, Mo, Cl, Co, Si and F. These
must be taken up and utilized in sufficent quantities for plants to complete
their life cycles. See: ESSENTIAL ELEMENTS.
Necrosis: The appearance of dead parts of
plants due to a lack of plant growth factors or the presence of toxics or
disease. Necrosis can also be confused with the normal senescense of plant
parts.
Nematodes: Elongated, cylindrical, unsegmented
worms; includes a number of plant parasites (a cause of root damage) and
human parasites.
Neutral Soil: A soil with pH values 6.5–7.3.
NIMBY: "Not in My Back Yard".
NIMTO: "Not in My Term of Office".
Nitrification: The oxidation of ammonia
to nitrite and nitrite to nitrate by microorganisms.
Nitrogen Fixation: The transformation
of elemental nitrogen to an organic form by microorganisms.
Nonhydric Soil: A soil that developed
dominately under oxygenated (aerobic) conditions.
Non-Silicate: Rock forming minerals that
do not contain silicon.
Nutrient: The elements C, H, O, P, K, N, S,
Ca, Mg, K, B, Mn, Cu, Zn, Mo, Cl, Co, Si, and F which are required for plant
growth.
Nutrient Deficiency: The lack of
an adequate amount of a plant nutrient. Nutrient deficiency may result in
a number of symptoms, including poor plant growth, chlorosis, or necrosis.
Nutrient deficiency symptoms can easily be confused with toxicity symptoms.
Obligate Aerobic Organisms:
Can only grow in the presence of oxygen.
Obligate Anaerobic Organisms:
Can only grow in the absence of oxygen.
Onion Skin Weathering: See: EXFOLIATION.
Order: See: SOIL ORDER.
Organic: Substances which include carbon-to-carbon
bonds.
Organic Contaminants: Synthetic
trace organics, including pesticides and polychlorinated biphenyls (PCB's).
Organic Matter: That portion of the
soil that includes microflora and microfauna (living and dead) and residual
decomposition products of plant and animal tissue; any carbon assembly (exclusive
of carbonates), large or small, dead or alive, inside soil space; generally
consists primarily of humus.
Organic Soil: A soil that is composed
predominantly of organic matter, usually refers to peat. See also: HISTOSOL.
Organic-N: Nitrogen in organic material.
Outwash: Glacially deposited soil parent material
worked and graded by water action from the melting glacial ice.
Oxidation: Energy-releasing process involving
removal of electrons from a substance; in biological systems, generally
by the removal of hydrogen (or sometimes by the addition of oxygen); chemical
and/or biochemical process combining carbon and oxygen and forming carbon
dioxide (CO2). See also: REDUCTION.
Oxygen Demand: See: BOD and COD.
Pans: Soil horizons that are strongly compacted,
cemented, or have a high content of clay.
Parent Material: The original state
of the soil. The relatively unaltered lower material in soils is often similar
to the material in which the horizons above have formed.
Particle Density: The weight per unit
volume of soil solids only.
Pathogen: An organism, chiefly a microorganism,
including viruses, bacteria, fungi, and all forms of animal parasites and
protozoa, capable of producing an infection or disease in a susceptible
host.
PCB's: Polychlorinated Biphenyls; a class of chlorinated
aromatic hydrocarbons representing a mixture of specific biphenyl hydrocarbons
which are thermally and chemically very stable; some are proven carcinogens.
Peat: An accumulation of dead plant material often
forming a layer many meters deep. It is only slightly decomposed due to
being completely waterlogged.
Ped: A single individual naturally occuring soil
aggregate such as a granule or prism. See: CLOD or FRAGMENT.
Pedogenesis: The natural process of soil
formation.
Pedology: The study of soils as naturally
occuring phenomena taking into account their composition, distribution,
and method of formation.
Pedounit: A selected column of soil containing
sufficient material in each horizon for adequate laboratory characterization.
Pedoturbation: All mixing of soil components
that is not caused by illuviation.
Peneplain: A large flat or gently undulation
area. Its formation is attributed to progressive erosion by rivers and rain,
which continues until almost all the elevated portions of the land surface
are worn down. When a peneplain is elevated, it may become a plateau which
then forms the initial stages in the development of a second peneplain.
Peraquic: A condition that results from a
high soil water table.
Perched Water Table: The upper
limit of perched water.
Percolation: (soil water) The downward
or lateral movement of water through soil.
Perennial: A plant that continues to grow
from year to year.
Permafrost: Permanently frozen subsoil.
Permanent Wilting Point: See: WILTING POINT.
Permanently flooded: A condition
where standing water covers the soil surface throughout normally wet years.
Permeability: The ease with which air
or plant roots penetrate into or pass through a specific horizon.
Persistence: Refers to a slowly decomposing
substance which remains active in the natural cycle for a long period of
time.
pH: The negative logarithm of the hydrogen ion concentration
of a solution. It is the quantitative expression of the acidity and alkalinity
of a solution and has a scale that ranges from about 0 to 14. pH 7 is neutral,
<7 is acid and >7 is alkaline.
pH, soil: The negative logarithm of the hydrogen
ion concentration of a soil solution. The degree of acidity or alkalinity
of a soil expressed in terms of the pH scale, from 2 to 10.
Physical Weathering: The communition
of rocks into smaller fragments by physical forces such as frost action
or exfoliation.
Physiological Drought: A temporary
daytime state of drought in plants due to the losses of water by transpiration
being more rapid than uptake by roots although the soil may have an adequate
supply. Such plants usually recover during the night.
Phytolith: Opaline formation in plant tissue
that remains in the soil after the softer plant tissue has decomposed.
Phytotoxic: Detrimental to plant growth;
caused by the presence of a contaminant.
Phytotoxin: Substance causing growth reduction
or death in plants.
Plagioclimax: A plant community which
is maintained by continuous human activity of a specific nature, such as
burning or grazing.
Plastic: A moist or wet soil that can be moulded
without rupture.
Platy: Soil aggregates that are horizontally
elongated.
Pleistocene Period: The period following
the Pliocene period, extending from 2,000,0000 to 10,000 years before the
present. In Europe and North America, there is evidence of four or five
periods of intense cold during this period, when large areas of the land
surface were covered by ice, glacial periods. During the interglacial periods,
the climate ameliorated and the glaciers retreated.
Pleochroism: (minerals). The changes in
color when some transparent minerals are rotated in plane polarized light.
It is expressed in terms of the nature and intensity of the color change.
Pluvial Period: A geologic period characterized
by heavy rainfall.
Podzolization: Used by some to refer
to the process of the formation of a podzol. This term is not specific and
should not be used.
Polder: A term used in Holland for an area reclaimed
from the sea or lake. A dyke is constructed around the area which is then
drained by pumping the water out. Polders form valuable agricultural land
or pasture land for cattle.
Polygenic Soil: A soil that has been
formed by two or more different and contrasting processes so that all of
the horizons are not genetically related.
Poorly Drained: See: STRONGLY ANAEROBIC.
Pore: A discrete volume of soil atmosphere completely
surrounded by soil. See: PORE SPACE).
Pore Space: The continuous and interconnecting
spaces in soils.
Porosity: The volume of the soil mass occupied
by pores and pore spaces, generally expressed as a percentage.
Preparation: Treatment of materials prior
to composting, including grinding, shredding, sorting, and adding sewage
sludge.
Primary Mineral: 1. A mineral such
as feldspar or mica which occurs or occurred originally in an igneous rock.
2. Any mineral which occurs in the parent material of the soil.
Primary nutrient: The elements P,
K, and N. These must be taken up and utilized in sufficent quantities for
plants to complete their life cycles. Normally present in quantities >1%.
Profile: A vertical section through a soil
from the surface into the relatively unaltered material.
Protein: Constituent of living matter containing
nitrogenous compounds.
Pseudomorph: A mineral having the characteristic
outward form of another mineral or object it replaces.
Puddle: To destroy the structure of the surface
soil by physical methods such as the impact of raindrops, poor cultivation
with implements, and trampling by animals.
Putrescible Waste: Organic materials
prone to degrade rapidly, giving rise to obnoxious odors.
Quaternary Era: The period of geological time following the Tertiary Era, it includes the Pleistocene and Holocene periods and extends from 2,000,000 years ago to the present.
Rain Splash Erosion: See: RAIN SPLASH.
Rain Splash: The redistribution of soil
particles on the surface by the impact of rain drops. On slopes this can
cause a large amount of erosion.
Rainfall Interception: The interception
and accumulation of rainfall by the foliage and branches of vegetation.
Raised Beach: A beach raised by earth
movement thus forming a narrow coastal plain. There may be raised beaches
at different levels resulting from repeated earth movement.
Raw Humus: A humus form consisting predominantly
of well preserved, though often fragmented plant remains with few faecal
pellets.
Reduction: The process of an element or compound
accepting an electron during a chemical reaction. See: OXIDATION.
Regolith: The unconsolidated mantle of weathered
rock, soil, and superficial deposits overlying solid rock.
Respiration: The metabolic function of
consuming oxygen.
Restricting horizon: The soil horizon
that most restricts movement of water or air movement vertically through
the soil, or restricts root growth down into soil. Restricting horizons
are often termed "PANS".
Rhizosphere: The soil close to plant roots
where there is usually an abundant and specific microbiological population.
Rill: A small intermittent water course with steep
sides.
Rill Erosion: The formation of rills as
a consequence of poor cultivation.
Rubification: The development of red color
in soil—reddening.
Runoff: Precipitation that doesn't penetrate
the soil and flows on the surface.
Saline Soil: A soil containing enough
soluble salts to reduce its fertility.
Salinity,
soil: The amount of soluble salts in a soil, commonly measured as the
electrical conductivity of a saturation extract.
Salinization: The process of accumulation
of salts in soil.
Sand: Mineral rock fragments that range in diameter
from 2–0.05 mm in the USDA system.
Saprist: Organic soils in which most of the
plant matter has decomposed (less than 1/3 of fibers remain visible after
rubbing), and the original tissue cannot be recognized.
Saturated Flow: The movement of water
in a soil that is completely filled with water.
Saturated soil: A soil for which the
entire profile is saturated with water.
Saturation: A property of color having to
do with its purity, the freedom from dilution with white. See: HUE and VALUE. See also: CHROMA.
Sclerotia: Spherical resting stages of fungi.
Screening: The sifting of compost through
a screen to remove large particles and improve the consistency and quality
of the end product.
Secondary Mineral: Those minerals
that form from the material released by weathering. The main secondary minerals
are the clays and oxides.
Secondary nutrient: The elements
S, Ca, Mg. These must be taken up and utilized in sufficent quantities for
plants to complete their life cycles. Normally present in quantities of
0.01–0.5%. See: ESSENTIAL ELEMENTS.
Sedimentary Rock: A rock composed
of sediments with varying degrees of consolidation. The main sedimentary
rocks include sandstones, shales, conglomerates, and some limestones.
Self-Mulching Soils: A soil with
a naturally formed well aggregated surface which does not crust and seal
under the impact of raindrops.
Semi-mature Compost: Material in
the mesophilic stage (it has passed through a thermophilic stage); the material
will reheat to 20°F above ambient temperature; organic matter has been
reduced by 40–60%.
Septage: Liquid and solid material pumped from
a septic tank or cesspool during cleaning.
Sesquioxides: Usually refers to the combined
amorphous oxides of iron and aluminium.
Sheet Erosion: The gradual and uniform
removal of the surface soil by water without forming any rills or gullies.
Shredder: Mechanical device used to break
waste materials into small pieces.
Silicates: Rock forming minerals that contain
silicon.
Silt: Mineral particles that range in diameter
from 0.02–0.002 mm in the international system or 0.05–0.002 mm
in the USDA system.
Size Reduction: Generic term for breaking
up solid waste or other materials into small pieces through crushing, chipping,
shredding, grinding, etc.; the process makes wastes easier to separate and
increases surface area for composting.
Slickenside: The polished surface that
forms when two peds rub against each other when some soils expand in response
to wetting.
Slickspot: Small area of surface soil that
is slick when wet because of alkalinity or high exchangeable sodium.
Sludge: Solid residue of the wastewater purification
process, a product of screening, sedimentation, filtering, pressing, bacterial
digestion, chemical precipitation, and oxidation; primary sludge is produced
by sedimentation process and secondary sludge is the product of microbial
digestion.
Slurry: A thin watery mixture of a fine insoluble
material.
Soil: (1) A dynamic natural body composed of mineral
and organic materials and living forms in which plants grow. (2) The collection
of natural bodies occupying parts of the earth's surface that support plants
and that have properties due to the integrated effect of climate and living
matter acting upon parent material, as conditioned by relief, over periods
of time.
Soil Amendment/Soil Conditioner: Soil
additive which stabilizes the soil, improves resistance to erosion, increases
permeability to air and water, improves texture and resistance of the surface
to crusting, eases cultivation, or otherwise improves soil quality.
Soil Anisotropy: The occurrence of
a vertical horizon sequence in soils causes vertical anisotropy to be an
essential characteristic. Frequently this vertical anisotropy can also be
observed in thin sections. See: ANISOTROPIC.
Soil Auger: A tool used for boring into
the soil and withdrawing small samples for field or laboratory examination.
Soil Classification: See: SOIL TAXONOMY
Soil Erratics: 1. Fragments of horizons
or other soil features transported and incorporated in superficial deposits
in which a soil may have formed or is forming. 2. Part of a previously existing
horizon preserved within a subsequently formed horizon.
Soil Fabric: The arrangement, size, shape,
and frequency of the individual soil constituents, excluding pores.
Soil Horizon: See: HORIZON.
Soil Order: The highest level of the U.S.
soil classification system. There are presently 11 soil orders, including
1) Entisols, 2) Inceptisols, 3) Spodosols, 4) Ultisols, 5) Alfisols, 6)
Vertisols, 7) Oxisols, 8) Histosols, 9) Andisols, 10) Aridosols, and 11)
Mollisols.
Soil Structure: See: STRUCTURE
Soil Suborder: The 2nd highest taxinomic
order of the U.S. soil classification system.
Soil Taxonomy: The systematic arrangement
of soils into groups or categories on the basis of their characteristics.
Soil Texture: The size distribution of
individual particles of a soil.
Soil Monolith: A vertical section through
the soil preserved with resin and mounted for display.
Soil Profile: A section of two dimensions
extending vertically from the earth's surface so as to expose all the soil
horizons and a part of the relatively unaltered underlying material.
Soil Survey: The systematic examination
and mapping of soil.
Soil Textural Triangle: A 3-phase
scale used to define soil into a soil textural group.
Solid Waste: Garbage, refuse, and other
discarded solid materials, including such materials resulting from industrial,
commercial, and agricultural operations and community activities.
Solifluction: Slow flow of material on
sloping ground, characteristic of, though not confined to, regions subjected
to alternate periods of freezing and thawing.
Solum: The part of the soil above the relatively
unaltered material.
Sphericity: Relates to the overall shape
of a feature irrespective of the sharpness of its edges and is a measure
of the degree of its conformity to a sphere.
Spodic horizon: A subsurface soil horizon
characterized by an accumulation of aluminum (also potentially iron) and
organic matter. This is the diagnostic horizon for the soil order Spodosol.
Spodosol: A soil order characterized by the
presence of a spodic horizon.
Springtails: Very small insects that live
in the surface soil and feed on organic matter.
Stability: State or condition in which the
composted material can be stored without giving rise to nuisances or can
be applied to the soil without causing problems there; the desired degree
of stability for finished compost is one in which the readily decomposed
compounds are broken down and only the decomposition of the more resistant
biologically decomposable compounds remains to be accomplished.
Stabilization: Stage in composting following
active decomposition; characterized by slow metabolic processes, lower heat
production and the formation of humus.
Static Pile System: An aerated static
pile with or without a controlled air source; See also: CONTROLLED
DYNAMIC SYSTEM; DYNAMIC PILE SYSTEM.
Strip Cropping: The practice of growing
crops in strips along the contour in an attempt to reduce runoff, thereby
preventing runoff and conserving moisture.
Strongly Anaerobic: (poorly drained)
Soil that remains very wet or waterlogged for long periods of the year and
as a result develops a mottled pattern of greys and browns.
Structure: The spatial distribution and total
organization of the soil system as expressed by the degree and type of aggregation
and the nature and distribution of pores and pore spaces.
Subhedral: Minerals with partly developed
crystallographic form.
Suborder: See: SOIL SUBORDER.
Symbiosis: Two organisms
that live together for their mutual benefit. Fungus and alga that forms
a lichen or nitrogen fixing bacteria living in roots are examples of symbiosis.
The individual organisms are called symbionts.
Synergism: The simultaneous action of separate
agencies which, together, create a greater total effect than the sum of
their individual effects.
Talus: Angular rock fragments that accumulate
by gravity at the foot of steep slopes of cliffs.
Tectonic: Rock structures produced by movements
in the earth's crust.
Terrace: A broad surface running along the
contour. It can be a natural phenomenon or specially constructed to intercept
runoff, thereby preventing erosion and conserving moisture. Sometimes they
are built to provide adequate rooting depths for plants.
Tertiary Period: The period of time
extending from 75,000,000 to 2,000,000 years before the present.
Texture: See: SOIL TEXTURE
Texture Triangle: See: SOIL TEXTURAL
TRIANGLE
Thermophilic Stage: A stage in the
composting process, characterized by active bacteria, which favors a high
temperature range of 45° to 75°C (113° to 167°F); it occurs
early, before the mesophilic stage, and is associated with a high rate of
decomposition.
Thermophyllic Bacteria: Bacteria
which have optimum activity between about 45° and 55° C.
Thorn Forest: A deciduous forest of small
thorny trees developed in a tropical semiarid climate.
Tile Drain: Short lengths of concrete or
pottery pipes placed end to end at a suitable depth and spacing in the soil
to collect water from the soil and lead it to an outlet.
Till: An unstratified or crudely stratified glacial
deposit consisting of a stiff matrix of fine rock fragments and an old soil
containing sub-angular stones of various sizes and composition, many of
which may be striated (scratched). It forms a mantle from less than 1 m
to over 100 m in thickness covering areas which carried an ice sheet or
glaciers during the Pleistocene and Holocene periods.
Till Plain: A level or undulating land surface
covered by glacial till.
Tilth: The physical state of the soil that determines
its suitability for plant growth taking into account texture, structure,
consistency, and pore space; a subjective estimation, judged by experience.
Toposequence: A sequence of soils whose
properties are determined by their particular topographic situation.
Topsoil: Soil consisting of various mixtures
of sand, silt, clay and organic matter; considered to be the nutrient-rich
top layer of soil that supports plant growth.
Toxic Substance: A substance that is
present in the soil or the above ground atmosphere that inhibits the growth
of plants and ultimately may cause deficiency symptoms or their death.
Toxicity: Adverse biological effect due to
toxins and other compounds.
Toxin: Unstable poison-like compound of biological
origin which may cause a reduction of viability or functionality in living
organisms. See: TOXIC SUBSTANCE.
Translocation: Migration of material
in solution or suspension from one horizon to another.
Traffic pan: Compacted soil horizon created
by the action of machinery, such as trucks, tractors, or logging skidders,
over the soil.
Triassic: A period of geological time extending
from 190,000,000 to 150,000,000 years before the present.
Tropical Rain Forest: See: EQUATORIAL
FOREST
Trough: Semi-enclosed windrow with automatic
turning equipment mounted on retaining walls.
Ultisol: A soil order characterized by higher
clay in the B-horizon than the A-horizon and an acid subsoil.
Ultramicropores: Pores <5 mm in
diameter.
Unavailable Nutrients: Plant
nutrients that are present in the soil but cannot be taken up by the roots
because they have not been released from the rock or minerals by weathering
or from organic matter by decomposition.
Unavailable Water: Water that is
present in the soil but cannot be taken up by plant roots because it is
strongly adsorbed onto the surface of particles.
Unconsolidated: Sediments that are loose
and not hardened.
Unsaturated Flow: The movement of
water in the soil that is not completely filled with water.
Upland: An area where soils are generally relatively
well drained such that the water table is significantly below the soil surface
most of the year.
Value: The relative lightness or intensity
of color, one of the three color variables. See: HUE
and SATURATION. See also: CHROMA
Varnish, desert: See: DESERT
VARNISH
Varve: A layer representing the annual deposit
of sediment. It usually consists of a lighter and darker portion due to
the change in rate of deposition, and hence particle size, during the year.
The material may be of any origin but the term is most often used in connection
with glacial lake sediments.
Vector: Animal or insect that transmits a disease-producing
organism, including rats, mice, mosquitos, etc.
Ventifact: A pebble faceted or moulded by
wind action, usually formed in desert or polar areas. The flat facets meet
at sharp angles.
Vermicomposting: The biological degradation
of organic matter contained in agricultural, urban, and industrial wastes
occurring when earthworms feed on these materials.
Vermiculture: Composting by the activity
of earthworms; material is eaten by the worms, leaving air passages which
maintain aerobic conditions; the process is completed with a curing stage.
Very Poorly Drained: A soil that
remains wet and waterlogged for most of the year so that most of the horizons
are blue, olive, or gray due to the reducing conditions.
Volatilization: Gaseous loss of a substance
to the atmosphere.
Volcanic Ash (Volcanic Dust): Fine particles
of lava ejected during a volcanic eruption. Sometimes the particles are
shot high into the atmosphere and carried long distances by the wind.
Sater mark: See: HIGH
WATER MARK.
Water Table (Ground): The upper limit in
the soil or underlying material permanently saturated with water.
Water Table (Perched): See: PERCHED
WATER TABLE.
Waterlogged: Saturated with water.
Weakly Anaerobic: A horizon that is
anaerobic for short periods and moist for long periods. The colors are less
bright than aerobic horizons and they are usually marbled or weakly mottled.
Weathering: All the physical, chemical,
and biological processes that cause the disintegration of rocks at or near
the surface.
Well Drained: See: AEROBIC.
Wetland: General definition: Areas that under
normal circumstances have hydric soils and hydrophytic vegetation.
Wetland soil: See: HYDRIC
SOIL.
Wilting Point: The percentage by weight
of water remaining in the soil when the plant wilts permanently.
Windrow System: Waste or bulking agent
mixture is placed in elongated piles, windrows, and aerated by mechanically
turning the piles with a machine such as a front-end loader or specially
designed equipment.
Wood Waste: Finished lumber, wood products,
and prunings or stumps six inches or greater in diameter.
Xerophytes: Plants that grow in extremely dry areas.
Yard Waste: Grass clippings, leaves, weeds, and prunings from residences or businesses six inches or less in diameter.
List as of 1/1/95
URL: http://ag.arizona.edu/OALS/IALC/soils/glossary.html
Last Revised: 25 April 1997