About an environment factor or an inorganic resource that is devoid of life, e.g. any physical, climatic, geologic or chemical feature of the environment, considered when affecting the life of various organisms or the soil formation and behavior.
The physio-chemical process by which a solid, a liquid or a gaseous substance penetrates and is rather uniformly incorporated into another solid or liquid substance. Absorption of water molecules or various ions by soil solid particles is of particular interest in soil science.
An arbuscular mycorrhiza is a type of mycorrhiza in which the symbiont fungus penetrates the cortical cells of the roots of a vascular plant forming arbuscules. AMF are soil-borne fungi that can significantly improve plant nutrient uptake and resistance to several abiotic stress factors.
Any substance containing H (hydrogen) that, dissolved in water, yields H ions (protons). A molecule or ion that can provide protons to a base.
A fertilizer, consisting mainly of NH 4 + salts, that after application to and interaction with the soil increases soil residual acidity and decreases soil pH. The increase in soil acidity is produced by nitrification of the fertilizer NH 4 + or by removal of basic cations by various fertilizer anions. The term has the same general meaning assigned to the term physiological acid fertilizer, but without the same motivation of increasing soil acidity.
A measure of the amount of acid in a solution, as in the soil solution, expressed as activity of H ions in that solution.
A micro-organism belonging to a group of the order Actinomycetales, consisting of gram-positive, aerobic and heterotrophic bacteria that present a superficial resemblance to fungi. Most soil actinomycetes are unicellular micro-organisms that produce a characteristic branched mycelium and multiply by segmentation of the entire mycelium or by segmentation of special terminal hyphae. They are commonly represented by species of Nocardia, Streptomyces and Micromonospora. Soil actinomycetes are active in the breakdown of the more resistant organic compounds of fresh residues or of humus and in producing vitamins and antibiotics. Some actinomycetes are symbiotic N fixers.
A pore large enough to play an active role in flow of water and air in soils. Pores larger than, e.g. 10 or 50 μm are considered by various authors and for different soils as being active pores. Active soil pores form the effective porosity of that soil.
A system which uses high livestock densities for short durations between adequate periods of forage recovery time to catalyze accelerated grass growth. The system is not scheduled or prescriptive but moves the animals in response to how land and life respond.
A physio-chemical process taking place at the gas – solid or liquid – solid interface, by which ions, atoms or molecules are accumulated and retained on the surface of the solid by chemical or physical binding. Soil colloids are very active in ionic, atomic and molecular adsorption from the soil solution and from the soil atmosphere.
Environmental conditions, processes or organisms characterized as having, occurring in, or living in the presence of molecular Oxygen. Most soils have, at least during part of the year, aerobic conditions.
A kind of respiration, an oxidation-reduction metabolic process in which molecular O2 acts as the ultimate electron acceptor. It is specific to higher animals and plants and to aerobic micro-organisms.
Is the biological and chemical fusion of primary particles (Clay, Slit and Sand) into a hierarchy of sub-microaggregates, micro-aggregates, and Macro-aggerates. This agglomeration is done with microbial by products, polysaccharides, root hairs, fungal hype and microbial debris.
The destruction of structural aggregates during a rapid wetting of the soil. It is largely due to compression of air inside the structural aggregates, and to pressure exerted by the compressed air.
The stability of soil aggregates referring to their resistance to disruptive effects of mechanical forces.
Soil biotic glues or organo-mineral substances created soil biota, fungi, and plants that bind primary particles into structural elements and peds. The main natural aggregation agents are organic matter (biotic glues, organic mineral complex substances), CaCO 3 and Fe 2 O 3 ·H2O.
The habitat of soil biota that live macro and micro pores of aggregates in the soil ecosystem. See aggregates and aggregation agent
A concept developed in the 19th century in Western Europe, closely related to the mineral nutrition concept. Soils are considered as a mixture of mineral and organic materials with specific chemical properties, serving merely as a source of nutrients for plants. They are classified mainly according to their chemical properties.
A field of science studying relationships between ecology and agriculture.
A concept developed in Western Europe in the 18th century, closely related to the earthy material nutrition concept and to the humus nutrition concept. Soils are considered as a mixture of mineral and organic materials with specific physical properties, serving merely as a support for plant growth. Most importance was given to soil texture and structure.
The process following which a soil, or a plant sample reaches the air-dry moisture content.
In a wide sense, a measurement of bases in a solution, expressed as concentration of hydroxyl ions in that solution. 2. A more specific sense, used in soil science, a capacity parameter in a system containing carbonates.
All of the detrimental effects of a plant species, due to toxic substances excreted by its roots or leaves, on another plant species growing nearby or in succession on the same site.
An organic acid containing the functional carboxyl (-COOH) and amino (-NH 2 ) groups. Amino acids occur in all plant and animal tissues and are considered the basic units of proteins. In soils, they are of plant or microbial origin, and occur as bound or transient free forms. In the soil solution, free amino acids form soluble chelates with metal ions.
A biological process leading to formation of ammoniacal N from N-containing organic compounds released during protein decomposition. It is performed by specific ammonifiers.
The univalent ion of ammonia (NH4+). Soil NH4+occurs in exchangeable and non-exchangeable positions in the adsorption complex, as well as being soluble in the soil solution. The amount of soluble NH4+ is extremely low in well-aerated soils. In other cases (grassland, forest soils of low pH, organic hydromorphic soils and sediments, recently fertilized soils and land used for disposal of wastes), soluble and exchangeable NH4+can increase to become a significant part of the soil inorganic N. Exchangeable NH4++ always remains in small amounts relative to other exchangeable cations.
Any micro-organism belonging to a highly specialized group of nitrifiers that oxidize NH4+ + to NO2- . The group includes species from the genera Nitrosomonas, Nitrosococcus, Nitrosospira and Nitrosoglea.
Any organism, including soil organisms, living in the absence of free molecular atmospheric O2 . Anaerobes may be obligate or facultative.
A kind of respiration, an oxygen-reduction metabolic process, specific to obligate or facultative anaerobic micro-organisms, whereby electrons are transferred from a reduced compound, usually an organic donor, to an inorganic acceptor, other than Oxygen. In soils, the most common electron acceptors are carbonate, sulphate and nitrate.
A natural fertilizer produced from solid and liquid excreta of domestic animals under controlled fermentation, sometimes with additives, in agricultural farms or in industrial livestock-raising units. Manure, semiliquid manure and liquid manure are differentiated.
Any ion with a negative charge. Anions move towards the anode (positive pole) when they are placed.
An aerobic heterotrophic bacterium that is free-living in soils, and is able to fix atmospheric molecular N for microbial synthesis, thus enriching the soil in N.
One of two domains of single celled prokaryote microorganisms. Includes all that are not Archaea.
A unicellular (sometimes multicellular) micro-organism, sporogenous or non-sporogenous, very widely distributed in nature. Since bacterial activity in soils is not strictly related to taxonomic units, these micro-organisms are preferentially classified from a physiologic or functional standpoint. Such classifications are made according to the type of nutrition, respiration or temperature requirement or to specific processes in which the bacteria are involved. Bacteria are the most abundant and diversified group within the soil microflora. They play a role in rock weathering and participate to most in organic matter decomposition and synthesis processes that determine soil formation, nutrient cycling, and soil fertility.
In chemistry, any substance that in water solution is slippery to the touch, tastes bitter, changes the color of indicators (e.g., turns red litmus paper blue), reacts with acids to form salts, and promotes certain chemical reactions (base catalysis). Examples of bases are the hydroxides of the alkali and alkaline earth metals (sodium, calcium, etc.) and the water solutions of ammonia or its organic derivatives (amines). Such substances produce hydroxide ions (OH-) in water solutions.
The extent to which the adsorption complex of a soil is saturated with exchangeable cations other than hydrogen and aluminum. It is expressed as a percentage of the total cation exchange capacity. See nonacid saturation.
A buildup within an organism of specific compounds due to biological processes. Commonly applied to heavy metals, pesticides, or metabolites.
The cleanup of contaminated soils by adding exotic microorganisms that are especially efficient at breaking down an organic contaminant. A form of bioremediation.
A black carbon condensate product purposefully made by heating organic mate rial at 300 to 700 °C under low oxygen conditions.
Subject to degradation by biochemical processes.
Occurs at or dinery temperatures and pressures. It is commonly carried out by certain bacteria, algae, and actinomycetes, which may or may not be associated with higher plants.
The total mass of living material of a specified type (e.g., microbial biomass) in a given environment (e.g., in a cubic meter of soil).
Soil pores, usually of relatively large diameter, created by plant roots, earth worms, or other soil organisms.
The decontamination or restoration of polluted or degraded soils by means of enhancing the chemical degradation or other activities of soil organisms.
A group of related soils that differ, one from the other, primarily because of differences in kinds and numbers of plants and soil organisms as a soil-forming factor.
Sewage sludge that meets certain regulatory standards, making it suitable for land application.
The cleanup of contaminated soils through the manipulation of nutrients or other soil environmental factors to enhance the activity of naturally occurring soil microorganisms. A form of bioremediation.
A low embankment with such gentle slopes that it can be farmed, constructed across sloping fields to reduce erosion and runoff.
Or fertilizer on the surface of the soil.
The ability of a soil to resist changes in pH. Commonly determined by presence of clay, and organic matter.
Solid fertilizer materials blended together in small blending plants, delivered to the farm in bulk, and usually spread directly on the fields by truck or another special applicator.
Mixing dry individual granulated fertilizer materials to form a mixed fertilizer that is applied promptly to the soil.
The mass of dry soil per unit of bulk volume, including the air space. The bulk volume is determined before drying to constant weight at 105 °C.
Carbon is an element found in all living things. Carbon atoms move constantly through living organisms, the oceans, the atmosphere, and the Earth's crust in what is known as the carbon cycle. All living things contain carbon. There are inorganic substances that also contain carbon. It is the backbone of macromolecules such as proteins, carbohydrates, nucleic acids and lipids.
The series of processes by which carbon compounds are interconverted in the environment, involving the incorporation of carbon dioxide into living tissue by photosynthesis and its return to the atmosphere through respiration, the decay of dead organisms, and the burning of fossil fuels.
The ratio of the weight of organic carbon (C) to the weight of total nitrogen (N) in a soil or in organic material. Carbon to Nitrogen Ratio: Refers to the balance of C:N in any living organism or decaying material. In the soil itself the ratio should be between 10:1-12:1.
An organism that feeds on animals.
A positively charged ion; during electrolysis it is attracted to the negatively charged cathode.
The interchange between an ion in solution and another cation on the surface of any surface-active material, such as clay or organic matter.
The sum total of exchangeable cations that a soil can adsorb. Sometimes called total-exchange capacity base-exchange capacity, or cation-adsorption capacity.
A tillage implement with one or more cultivator-type feet to which are attached strong knifelike units used to shatter or loosen hard, compact layers, usually in the subsoil, co depths below normal plow depth.
A condition in plants relating to the failure of chlorophyll (the green coloring matter) to develop. Chlorotic leaves range from light green through yellow to almost white.
A compact, coherent mass of soil produced artificially, usually by such human activities as plowing and digging, especially when these operations are performed on soils that are either too wet or too dry for normal tillage operations.
Force holding a solid or liquid together, owing to attraction between like molecules. Decreases with rise in temperature.
Certain soil that may undergo a sudden loss in strength when wetted.
The practice of growing certain species of plants in proximity because one species has the effect of improving the growth of the other, sometimes by positive allelopathic effects.
Organic residues, or a mixture of organic residues and soil, that have been piled, moistened, and allowed to undergo biological decomposition. Mineral fertilizers are sometimes added. Often called artificial manure or synthetic manure if produced primarily from plant residues.
A local concentration of a chemical compound, such as calcium carbonate or iron oxide, in the form of grains or nodules of varying size, shape, hardness, and color.
nearly level throughout its course.
In comparatively narrow strips in which the farming operations are performed approximately on the contour. Usually strips of grass, close-growing crops, or fallow are alternated with those of cultivated crops.
The act of grazing a particular pasture or area the entire year, including the dormant season.
A farming system in which all wheeled traffic is confined to fixed paths so that repeated compaction of the soil does not occur outside the selected paths.
A close-growing crop grown primarily for the purpose of capturing solar energy, enhancing biodiversity above/below the ground, feed soil biology, sequester nutrients, and protect soil between periods of regular crop production or between trees and vines in orchards and vineyards.
A planned sequence of crops growing in a regularly recurring succession on the same area of land, as contrasted to continuous culture of one crop or growing different crops in haphazard order.
A soft, porous, more or less rounded natural unit of structure from 1 to 5 mm in diameter. See also soil structure types.
The force required to crush a mass of dry soil or, conversely, the resistance of the dry soil mass to crushing. Expressed in units of force per unit area (pressure).
A tillage operation used in preparing land for seeding or Transplanting or later for weed control and for loosening the soil.
Chlorophyll-containing bacteria that accommodate both photosynthesis and nitrogen fixation. Formerly called blue green algae.
A plant that sheds all its leaves every year at a certain season.
Chemical breakdown of a compound (e.g., a mineral or organic compound) into simpler compounds, often accomplished with the aid of microorganisms.
The biochemical reduction of nitrate or nitrite to gaseous nitrogen, either as molecular nitrogen or as an oxide of nitrogen.
The volume of soil solution adjacent to plant roots where the concentration of an element has been reduced by plant uptake that is faster than diffusion can replace the element from the bulk solution. Often used in reference to phosphorus or potassium.
Removal of salts from saline soil, usually by leaching.
A hard layer, containing calcium carbonate, gypsum, or other binding material, exposed at the surface in desert regions.
The removal of sorbed material from surfaces.
An organism that subsists on detritus.
Debris from dead plants and animals.
In soil biology, detritus is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts communities of microorganisms that colonize and decompose it. A habitat for insects and mesofauna.
The movement of atoms in a gaseous mixture or of ions in a solution, primarily as a result of their own random motion.
To break up compound particles, such as aggregates, into the individual component particles. (2) To distribute or suspend fine particles, such as clay, in or throughout a dispersion medium, such as water.
Process by which molecules of a gas, solid, or another liquid dissolve in a liquid, hereby becoming completely and uniformly dispersed throughout the liquid's volume.
The practice of crop production in low-rainfall areas without irrigation.
The sphere or area impacted by earthworm secretions that are rich in bacterial life and other minerals like phosphorous.
The matted, partly decomposed organic surface layer of forest soils.
A loose, finely granular or powdery condition on the surface of the soil, usually produced by shallow cultivation.
Animals of the Lumbricidae family that burrow into and live in the soil. They mix plant residues into the soil and improve soil aeration.
A dynamic and interacting combination of all the living organisms and nonliving elements (matter and energy) of an environment.
The combined loss of water from a given area, and during a specified period of time, by evaporation from the soil surface and by transpiration from plants.
The total ionic charge of the adsorption complex active in the adsorption of ions. See also anion exchange capacity, cation exchange capacity.
A symbiotic association of the mycelium of fungi and the roots of certain plants in which the fungal hyphae form a compact mantle on the surface of the roots. Associated primarily with certain trees.
That portion of the total precipitation that becomes available for plant growth or for the promotion of soil formation.
The capacity of a substance to conduct or transmit electrical current. In soils or water, measured in Siemens/meter (or often dS/m), and related to dissolved solutes.
A symbiotic association of the mycelium of fungi and roots of a variety of plants in which the fungal hyphae penetrate directly into root hairs, other epidermal cells, and occasionally into cortical cells. Individual hyphae also extend from the root surface outward into the surrounding soil. See also arbuscular mycorrhiza.
The concentration of phosphorus in a solution in equilibrium with a soil, the EPCO being the concentration of phosphorus achieved by desorption of phosphorus from a soil to phosphorus-free distilled water.
The wearing away of the land surface by running water, wind, ice, or ocher geological agents, including such processes as gravitational creep.
Nutrient enrichment of lakes, ponds, and other such waters that stimulates the growth of aquatic organisms, which leads to a deficiency of oxygen in the water body.
An organism capable of both aerobic and anaerobic metabolism.
Cropland left idle in order to restore productivity, mainly through accumulation of water. Preceding a cereal grain crop in semiarid regions, land may be left in summer fallow for a period during which weeds are controlled by chemicals or tillage and water is allowed to accumulate in the soil profile. In humid regions, fallow land may be allowed to grow up in natural vegetation for a period ranging from a few months to many years.
The application of fertilizers in irrigation waters, commonly through sprinkler systems.
The quality of a soil chat enables it to provide essential chemical elements in quantities and proportions for the growth of specified plants.
Any organic or inorganic material of natural or synthetic origin added to a soil to supply certain elements essential to the growth of plants.
The percentage of water remaining in a soil two or three days after its having been saturated and after free drainage has practically ceased prevents interlayer expansion and swelling, and limits interlayer cation exchange capacity.
To aggregate or clump together individual, tiny soil particles, especially fine clay, into small clumps or floccules. Opposite of deflocculated or disperse.
An estimation of mineral nutrient deficiencies (excesses) of plants based on examination of the chemical composition of selected plant parts, and the color and growth characteristics of the foliage of the plants.
The community of organisms that relate to one another by sharing and passing on food substances. They are organized into trophic levels such as producers that create organic substances from sunlight and inorganic matter, to consumers and predators that eat the producers, dead organisms, waste products and each other.
A soil consistency term pertaining to soils that crumble with ease.
The characteristic of an ecosystem exemplified by the capacity to carry out a large number of biochemical trans formations and other functions.
Eukaryote microorganisms with a rigid cell wall. Some form long filaments of cells called hyphae that may grow together to form a visible body.
The uppermost layer of an arable soil to the depth of primary tillage. The depth of the plow.
The process of producing granular materials. Commonly used co refer to the formation of soil structural granules, but also used to refer to the processing of powdery fertilizer materials into granules.
Broad and shallow channel, planned with grass (usually perennial species) that is designed to move surface water downslope without causing soil erosion.
Plant material incorporated with the soil while green, or soon after maturity, for improving the soil.
The quantity of gypsum required to reduce the exchangeable sodium percentage in a soil to an acceptable level.
A hardened soil layer, in the lower A or in the B Horizon, caused by cementation of soil particles with organic matter or with such materials as silica, sesquioxide’s, or calcium carbonate. The hardness does not change appreciably with changes in moisture content and pieces of the hard layer do not slake in water.
A secondary broadcast till age operation that pulverizes, smooths, and firms the soil in seedbed preparation, controls weeds, or incorporates material spread on the surface.
Those metals that have densities of 5.0 Mg/m or greeter. Elements in soils include Cd, Co, Cr, Cu, Fe, Hy, Mn, Mo, Pb, and Zn.
(Obsolete in scientific use) A soil with a high content of clay, and a high draw bar pull, hence difficult to cultivate.
A plant-eating animal.
An organism capable of deriving energy for life processes only from the decomposition of organic compounds and in capable of using inorganic compounds as sole sources of energy or for organic synthesis. Contrast with autotroph.
The portion of soil organic matter that is not alive or recognizable plant tissue and is protected from rapid decomposition co some degree by the soil environment. It is generally colloidal in particle size and black in color. Previously thought to be composed mainly of very large polymer molecules operationally defined as humic acids, folic acids and humin, which see.
Chemical union between an ion or compound and one or more water molecules, the reaction being stimulated by the attraction of the ion or compound for either the hydrogen or the unshared electrons of the oxygen in the water.
An expression of the readiness with which a liquid, such as water, flows through a solid, such as soil, in response to a given potential gradient.
Soils that are water-saturated for long enough periods to produce reduced conditions and affect the growth of plants.
The circuit of water movement from the atmosphere to the Earth and back to the atmosphere through various stages or processes, as precipitation, interception, runoff, infiltration, percolation, storage, evaporation, and transpiration.
The erosion process whereby water accumulates to narrow channels and, over short periods.
The process of producing granular materials. Commonly used to refer to the formation of soil structural granules, but also used to refer to the processing of powdery fertilizer materials into granules.
Plant-production systems chat use nutrient solutions and no solid medium to grow plants.
Filament of fungal cells. Actinomycetes also produce similar, but thinner, filaments of cells.
State of oxygen deficiency in an environment so low as to restrict biological respiration (in water, Typically less than 2 to 3 mg O/L).
The conversion of an element from the inorganic to the organic form in microbial tissues or in plant tissues, thus rendering the element not readily available to other organisms or to plants.
The mineral component of soil derived from non-living sources, such as rocks or water. It is not bound to a carbon molecule.
The ratio of the water actually consumed by crops on an irrigated area to the amount of water diverted from the source onto the area.
An organism that maintains a relatively stable population by specializing in metabolism of resistant compounds that most other organisms cannot utilize. Contrast with -R-strategist. See also autochthonous organisms.
A substance that is readily transformed by microorganisms or is readily avail
sweet clovers, lespedezas, vetches, and kudzu. what it needs. For example, if potassium is able for uptake by plants.
Falling over of plants, either by up dark in color, and has a very low bulk density total upper leaf surface of a plane canopy and rooting or stem breakage, and high anion adsorption capacity. the unit area on which the canopy is grown.
Animals of medium size, between approximately 2 and 0.2 mm in diameter.
Pertaining to moderate temperatures in the range of 15 to 35 °C.
(CH4) An odorless, colorless gas commonly produced under anaerobic conditions. When released to the upper atmosphere, methane contributes to global warming.
That part of the animal population which consists of individuals too small to be clearly distinguished without the use of a microscope. Includes protozoans and nematodes.
That part of the plant population which consists of individuals too small to be clearly distinguished without the use of a microscope. Includes actinomycetes, algae, bacteria, and fungi.
A chemical element necessary in only extremely small amounts (<50 mg/kg in the plant) for the growth of plants. Examples are B, CI, Cu, Fe, Mn, and Zn. (Micro refers to the amount used rather than to its essentiality.) See also macronutrient.
An inorganic compound of defined composition found in rocks. An adjective meaning inorganic.
An element in inorganic form used by plants or animals. com mineral soil A soil consisting predominantly of, and having its properties determined predominantly by, mineral matter. Usually contains <20% organic matter but may contain an organic surface layer up to 30 cm thick.
The conversion of an element from an organic form to an inorganic state as a result of microbial decomposition. Mineralized nutrients are in a plant available form. Immobilization and Mineralization are constantly going from an organic to an inorganic state. This is a biological process which is dependent on moisture and temperature.
A stringlike mass of individual fungal or actinomycetes hyphae.
The association, usually symbiotic, of fungi with the roots of seed plants. See also ectotrophic mycorrhiza, endotrophic mycorrhiza, arbuscular mycorrhiza.
Very small (most are microscopic) unsegmented round worms. In soils they are abundant and perform many import and functions in the soil food web.
A system/philosophy of agriculture that does not allow the use of synthetic.
By-product from the processing of animal or vegetable substances that contain sufficient
plant nutrients to feed plants.
The biochemical oxidation of ammonium to nitrate, predominantly by autotrophic bacteria.
In soils is present in the form of amino acids, proteins and in microbial tissue. It becomes available to plants once it is decomposed by microorganisms.
The incorporation of nitrogen into organic cell substances by living organisms.
The sequence of chemical and biological changes undergone by nitrogen as it moves from the atmosphere into water, soil, and living organisms, and upon death of these organisms (plants and animals) is recycled through a part or all of the entire process.
The biological conversion of elemental nitrogen (N2) to organic combinations or to forms readily utilized in biological processes.
A type of conservation practice that plants seed with a no-till planter without disrupting the soil surface. This practice protects soil habitat and soil organisms from intrusive tillage forces that destroys soil habitat (aggerates) and negatively impacts fungi plus other soil biota.
A microbially active fraction of soil organic matter consisting largely of fine particles of partially decomposed plant tissue.
Unconsolidated soil material consisting largely of undecomposed, or only slightly decomposed, organic matter accumulated under conditions of excessive moisture.
An instrument consisting of a rod with a cone-shaped tip and a means of measuring the force required to push the rod into a specified increment of soil.
Permanently frozen mace rial underlying the solum. A perennially frozen soil horizon.
The negative logarithm of the hydrogen ion activity (concentration of a soil. The degree of acidity (or alkalinity) of a soil as determined by means of a glass or other suitable electrode or indicator at a specified moisture content or soil-to-water ratio, and expressed in terms of the pH scale.
The leaf surface.
(of soils) Those characteristics, processes, or reactions of a soil that are caused by physical forces and that can be described by, or expressed in, physical terms or equations. Examples of physical properties are bulk density, water-holding capacity, hydraulic conductivity, porosity, pore-size distribution, and so on.
Chemicals that are toxic to plants.
See essential element.
The soil ordinarily moved when land is plowed; equivalent to surface soil.
The volume percentage of the total soil bulk not occupied by solid particles.
The acidity that could potentially be formed if reduced sulfur compounds in a potential acid sulfate soil were to become oxidized.
The spatially variable management of a field or farm based on information specific to the soil or crop characteristics of many very small subunits of land. This technique commonly uses variable rate equipment, geo positioning systems and computer controls.
An organism that subsists on plant material.
An organism, usually a photosynthetic plant that creates organic, energy-rich material from inorganic chemicals, solar energy, and water.
The first soil tillage after the last harvest. It is normally conducted when the soil is wet enough to allow plowing and strong enough to give reasonable levels of traction. This can be immediately after the crop harvest or at the beginning of the next wet season.
The increased decomposition of relatively stable, protected soil humus under the influence of much enhanced, generally biological, activity resulting from the addition of fresh organic materials co a soil.
The capacity of the soil to function as a living ecosystem for producing a specified plant or sequence of plants under a specified system of management.
One-celled eukaryotic organisms, such as amoeba. A group of single celled organisms, either free living or parasitic, which feed on other micro-organisms or organic tissues or debris.
A hand-held instrument used to give an indication of the nutrient density in a plant.
Unconsolidated and partly weathered mineral materials accumulated by disintegration of consolidated rock.
The capacity of a soil (or other ecosystem) to return to its original state after a disturbance.
Specially adapted to colonizing the surface of plant roots and the soil immediately around plant roots.
The root surface-soil interface. Used to describe the habitat of root-surface-dwelling microorganisms.
That portion of the soil in the immediate vicinity of plant roots in which the abundance and composition of the microbial population are influenced by the presence of roots.
Plants cultivate—essentially farm—microbes around root tips by secreting sugars, proteins and vitamins. The microbes grow and then enter root cells at the tips, where cells are dividing and lack hardened walls. The microbes lose their cell walls, become trapped in plant cells, and are hit with reactive oxygen (superoxide). The reactive oxygen breaks down some of the microbe cells, effectively extracting nutrients from them. Surviving microbes spur the formation of root hairs on roots. The microbes leave the hairs at the growing hair tip, where the hair cell wall is soft, and microbes reform their cell walls as they reenter soil.
An erosion process in which numerous small channels of only several centimeters in depth are formed; occurs mainly on recently cultivated soils. See also rill.
Are composed of sugars, proteins and organic acids that are released by living plants. The exudates help attract microbiology.
Acquisition of nutrients by a root as a result of the root growing into the vicinity of the nutrient source.
Swollen growths on plant roots. Often in reference to those in which symbiotic microorganisms live.
Opportunistic organisms with short reproductive times that allow them to respond rapidly to the presence of easily metabolized food sources. These organisms are activated with tillage, manure and other soil food sources. Contrast with k strategist.
An area of land in which saline water seeps to the surface, leaving a high salt concentration behind as the water evaporates.
A non-sodic soil containing sufficient soluble salts to impair its productivity. The conductivity of a saturated extract is >4 dS/m, the exchangeable sodium adsorption ratio is less than about 13, and the pH is <8.5.
A soil containing sufficient exchangeable sodium to interfere with the growth of most crop plants and containing appreciable quantities of soluble salts.
The process of accumulation of salts in soil.
The largest group of fungi that grow on dead organic matter. They are the first decomposers, along with bacteria.
A grassland with scattered trees, either as individuals or clumps. Often a transitional type between true grassland and forest.
Grazing a particular pasture or area for an entire growing season.
The soil prepared to promote the germination of seed and the growth of seedlings.
A soil in which the surface layer becomes so well aggregated that it does not crust and seal under the impact of rain but instead serves as a surface mulch upon drying.
Term applied to regions or climates where moisture is more plentiful chance in arid regions but still definitely limits the growth of most crop plants.
The removal of a fairly uniform layer of soil from the land surface by runoff water.
A wind barrier of living trees and shrubs established and maintained for protection of farm fields. Syn. windbreak.
The application of fertilizer alongside row-crop plants, usually on the soil surface. Nitrogen materials are most commonly side-dressed.
That portion of soil organic matter that can be metabolized with great difficulty by the microorganisms in the soil and therefore has a slow turnover rate with a half-life in the soil ranging from a few years to a few decades. are in the smectite group.
A soil that contains sufficient sodium to interfere with the growth of most.
It is the secretions and excretions of soil organisms that create polymers, polysaccharides, organo-mineral complexes, and other super molecules which modifies the geological matrix into soil habitat for living organisms.
The organic fraction with planes to create a living vegetation bar.
It is commonly determined as and living organisms which can serve as a named.
The ability of the soil to function as a self-regulating, self-healing and self-organizing ecosystem.
The number of soluble salts in the soil matrix.
A tool used to bore small holes.
The process of heating a soil in the field by covering it with clear plastic sheeting during sunny conditions. The heat is meant to partially sterilize the upper 5 to 15 cm of soil to reduce pest and pathogen populations.
The removal from the soil solution of an ion or molecule by adsorption and absorption. This term is often used when the exact mechanism of removal is not known.
The variety of different biological species present in an ecosystem. Generally, high diversity is marked by many species with few individuals in each.
The number of different species present in an ecosystem, without regard to the distribution of individuals among those species.
Pounds of livestock per acre.
Number of head per acre.
The practice of growing crops that require different types of tillage, such as row and sod, in alternate strips along contours or across the prevailing direction of wind.
The stubble of crops or crop residues left essentially in place on the land as a surface cover before and during the preparation of the seedbed and at least partly during the growing of a succeeding crop.
That part of the soil below the plow layer.
Breaking of compact subsoils. without inverting them, with a special knife-like instrument (chisel), which is pulled through the soil at depths usually of 30 TO 60 cm and at spacings usually of 1 to 2 m.
A thin layer of fine particles deposited on the surface of a soil that greatly reduces the permeability of the soil surface to water.
The elastic like phenomenon resulting from the unbalanced attractions among liquid molecules (usually water) and between liquid and gaseous molecules (usually air) at the liquid-gas interface.
The living together in intimate association of two dissimilar organisms, the cohabitation being mutually beneficial.
The nonobligatory association between organisms that is mutually beneficial, both populations can survive in their natural environment on their own, although, when formed, the association offers mutual advantages. (ii) The simultaneous actions of two or more factors that have a greater total effect together than the sum of their individual effects.
Pertaining to temperatures in the range of 45 to 90 °C, the range in which thermophilic organisms grow best and in which thermophilic composting takes place.
Organisms that grow readily are temperatures above 45 °C.
The mechanical manipulation of soil least 30% of the soil surface covered by residues, including the following systems:
The minimum soil manipulation necessary for crop production of meeting tillage requirements under the existing soil and climatic conditions.
Tillage or preparation of the soil in such a way that plant residues or other materials are left to cover the surface; also called mulch farming, trash farming, stubble mulch tillage, and plowless farming.
A procedure whereby a crop is planted directly into a seedbed no-tilled since harvest of the previous crop also called zero tillage.
Planting on ridges formed by cultivation during the previous growing period. strip till Planting is done in a narrow scrip chat has been filled and mixed, leaving the remainder of the soil surface undisturbed.
The combined primary and secondary tillage operations normally performed in preparing a seedbed for a given crop grown in a given geographic area. Usually said of non-conservation tillage.
Tillage that contributes to the major soil manipulation, commonly with a plow.
An operation using a pow er-driven rotary tillage cool to loosen and mix soil.
Any tillage operations following primary tillage designed to prepare a satisfactory seedbed for planting.
The physical condition of soil as related to its ease of tillage, fitness as a seedbed, and its impedance to seedling emergence and root penetration.
An application of fertilizer to a soil after the crop stand has been established.
Levels in a food chain that pass nutrients and energy from one group of organisms to another.
Dry matter or harvested portion of crop produced per unit of water consumed.
Saturated with water.
All the land and water within the geographical confines of a drainage divide or surrounding ridges that separate the area from neighboring watersheds.
A soil aggregate stable to the action of water, such as falling drops or agitation, as in wet-sieving analysis.
All physical and chemical changes produced in rocks, or near the Earth's surface, by atmospheric agents.
An area of land that has hydric soil and hydrophytic vegetation, typically flooded for part of the year, and forming a transition zone between aquatic and terrestrial systems.
The boundary between the wetted soil and dry soil during infiltration of water.
The moisture content of soil, on an oven-dry basis, at which plants wilt and fail to recover their turgidity when placed in a dark, humid atmosphere.
Planting of crees, shrubs, or other vegetation perpendicular, or nearly so, to the principal wind direction to protect soils, crops, homesteads, etc., from wind and snow.
So-called opportunist organisms found in soils in large numbers immediately following addition of readily decomposable organic materials.
References:
Elsevier’s Dictionary of Soil Science
The Nature and Properties of Soils 15th Edition Ray R. Weil, Nyle C. Brady