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| The layer(s) of generally loose mineral and/or organic material that are affected by physical, chemical, and/or biological processes at or near the planetary surface, and usually hold liquids, gases and biota and support plants. |
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| The quality of a soil that enables it to provide nutrients in adequate amounts and in proper balance for the growth of specified plants or crops. |
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| 1:1 clay minerals-structural definition and examples |
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Definition
| made up of one tetrahedral and one octahedral sheet per each clay layer (e.g., kaolinite, serpentine, and halloysite) |
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| 2:1 clay minerals-structural definition and examples |
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Definition
| composed of one octahedral sheet sandwiched between two tetrahedral sheets (e.g., montmorillonite, bentonite, laponite, micas (Mica is a generic term used for a group of complex aluminosilicate), talc, vermiculite, saponite, hectorite, sepiolite, and illite) |
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| unit of land measurement in the British Imperial and United States Customary systems, equal to 43560 square feet, or 4840 square yards. |
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| a unit of surface, or land, measure equal to 100 ares, or 10,000 square meters: equivalent to 2.471 acres. |
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| An atom or atomic group that is negatively charged because of a gain in electrons |
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| Unconsolidated, pyroclastic material less than 2 mm in all dimensions. Commonly called "volcanic ash". Compare cinders, lapilli, tephra. |
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| An atom or atomic group that is positively charged because of a loss in electrons. |
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| The interchange between a cation in solution and another cation in the boundary layer between the solution and surface of negatively charged material such as clay or organic matter |
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| Cation, anion exchange capacities |
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Definition
| The sum of exchangeable bases plus total soil acidity at a specific pH, values, usually 7.0 or 8.0. When acidity is expressed as salt extractable acidity, the cation exchange capacity is called the effective cation exchange capacity (ECEC) because this is considered to be the CEC of the exchanger at the native pH value. It is usually expressed in centimoles of charge per kilogram of exchanger (cmolckg-1) or millimoles of charge per kilogram of exchanger. See also acidity, total. |
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| Chemical weathering weathering of rocks and minerals |
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Definition
| The breakdown of rocks and minerals due to the presence of water and other components in the soil solution or changes in redox potential. See also weathering. |
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Definition
| A soil separate consisting of particles <0.002 mm in equivalent diameter. A naturally occurring material composed primarily of fine-grained minerals, which is generally plastic at appropriate water contents and will harden when dried or fired. Although clay usually contains phyllosilicates, it may contain other materials that impart plasticity and harden when dried or fired. Associated phases in clay may include materials that do not impart plasticity and organic matter. |
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| A random movement of ions or molecules due to thermal agitation which tends to move because of their chemical activity gradient from areas of higher to lower concentration. |
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| Plant material incorporated into soil while green or at maturity, for soil improvement. |
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| The decomposed dried excrement of birds and bats, used for fertilizer. |
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Definition
| The well decomposed, more or less stable part of the organic matter in mineral soils. Humas is an organic soil material which is also one of the USDA textures of muck (sapric soil material), mucky peat (hemic soil material), or peat (fibric soil material.) Most likely it is muck. |
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Definition
| The replacement of one atom by another of similar size in a crystal structure without disrupting or seriously changing the structure. When a substituting cation is of a smaller valence than the cation it is replacing, there is a net negative charge on the structure. |
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| Law of Diminishing Returns |
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Definition
| When other factors in production do not change, successive increases in the input of one factor will not proportionately increase product yield. |
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| Liebig's Law (Law of minimum) |
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Definition
| The growth and reproduction of an organism is dependent on the nutrient substance that is available in minimum quantity. |
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Definition
| A plant nutrient found at relatively high concentrations ( >500 mg kg-1) in plants. Usually refers to N, P, and K, but may include Ca, Mg, and S. |
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Definition
| The excreta of animals, with or without an admixture of bedding or litter, fresh or at various stages of further decomposition or composting. In some countries may denote any fertilizer material. |
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| The movement of solutes associated with net movement of water. |
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Definition
| A plant nutrient found in relatively small amounts( <100 mg kg-1) in plants. These are usually B, Cl, Cu, Fe, Mn, Mo, Ni, Co, and Zn. |
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Definition
| The depressing effect caused by one or more plant nutrients on the uptake and availability of another nutrient in the plant. |
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| A low concentration of an essential element that reduces plant growth and prevents completion of the normal plant life cycle. |
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| Quality, state or degree of harmful effect from an essential nutrient in sufficient concentrations in the plant. |
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| The breakdown of rock and mineral particles into smaller particles by physical forces such as frost action. See also weathering. |
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| The concentration of solutions expressed in weight or mass units of solute (dissolved substance) per million weight or mass units of solution. (ii) A concentration in solids expressed in weight or mass units of a substance contained per million weight or mass units of solid, such as soil. |
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| A mineral that has not been altered chemically since deposition and crystallization from molten lava. See also secondary mineral. |
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Definition
| The zone of soil immediately adjacent to plant roots in which the kinds, numbers, or activities of microorganisms differ from that of the bulk soil. |
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| A mineral resulting from the decomposition of a primary mineral or from the reprecipitation of the products of decomposition of a primary mineral. See also primary mineral. |
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Definition
an organic nitrogenous acid from which protein molecules are constructed
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| any of various chemical compounds composed of carbon, hydrogen, and oxygen, such as sugars, starches, and cellulose |
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Definition
a carbohydrate polysaccharide composed of glucose units; major component of plant primary cell wall
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Definition
| a complex organic substance or group of substances that impregnate the cell walls of xylem vessels and certain other plant cells; a major constituent of wood |
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| the genetic material of all living organisms, including DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) |
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Definition
a nitrogen-containing organic compound composed of units called amino acids
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Definition
| the tightly intertwined layer of plant litter from accumulations of undecomposed or partially decomposed plant residues |
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Definition
| Found in semiarid to moist areas. Result from weathering processes that leach clay minerals and other constituents out of the surface layer and into the subsoil, where they can hold and supply moisture and nutrients to plants. They formed primarily under forest or mixed vegetative cover and are productive for most crops. ~10% of ice-free land surface. |
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| essential nutrient criteria |
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Definition
is needed for the plant to complete growth cycle
performs a function that cannot be done by another element
is directly or indirectly involved in plant metabolic processes. |
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