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30 Cards in this Set
- Front
- Back
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Interception |
Precipitation that falls on vegetation and never reaches the soil |
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Infiltration |
Precipitation that reaches the soil and enters the soil as liquid water |
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Surface Runoff |
Water that flows off the soil surface when the rate of accumulation exceeds the rate of infiltration or the soil storage capacity |
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Drainage |
Water the percolates through the soil and is lost from the rooting zone |
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Evapotranspiration |
Water vapor loss from soil by evaporation from the soil surface and transpiration from foliage |
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Water Balance Equation |
SS=P-(R+D+ET) SS - Soil storage P - precipitation ( and irrigation ) R - Runoff D - Drainage ET - Evapotranspiration |
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Infiltration Excess |
Rate of precipitation exceeds rate of infiltration |
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Saturation Excess |
Amount of precipitation exceeds the water-holding capacity of the soil |
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Anaerobic condition |
Condition of absent of molecular oxygen; enable to produce reduced nitrogen gasses, hydrogen sulfide, methane, and ethylene |
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Mass Flow |
Physical movement of air; facilitated primarily by large fluctuations in soil moisture content; factors that influence mass flow are the wind, changes in atmospheric pressure, and root extraction of soil water |
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Diffusion |
Molecules of the individual gasses that comprise the air mixture move in response to concentration gradients of those gasses |
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Phyllosilicate |
Most important silicate clays because of their leaf-like structure |
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Tetrahedral sheet |
Sheet that is composed of 4 oxygen elements and one silicon element |
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Octahedral Sheet |
Sheet that is composed of 6 oxygen/hydroxyl elements and one aluminum or magnesium element |
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The ratio of 1:1 or 2:1 |
1:1 = 1 Tetrahedral sheet: 1 Octahedral sheet 2:1 = 2 Tetrahedral sheet: 1 Octahedral sheet Betweehn these sheets, oxygens are shared |
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Isomorphic Substitution |
The replacement of one atom by another of similar size in a crystal lattice without disrupting or changing the crystal structure of the mineral |
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Permanent Charge |
A permanent feature of clay that has lack of balance of electrical charge due to isomorphic substitution |
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Anions |
NEGATIVE charged ions that are attracted to positively charged site |
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Cation |
POSITIVE charged ions that are attracted to negatively charged site |
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Absorption |
Ability of an object to attract and hold particles on its surface |
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Ratio Law |
The ratio of similar cation absorbed on a colloid surface will be equivalent to the ratio of cations in the soil solution |
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Cation Selectivity |
Cation with higher charge on a smaller hydrated cation radius tends to hold more tightly on colloid surfaces |
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Cation Exchange Capacity (CEC) |
The total amount of cations that a soil can retain per units |
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Anion Exchange |
Exchange of anions in the soil solution for anions absorbed on the surface of clay and humus particles |
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Anion Exchange Capacity |
The sum total of exchangeable anions that a soil can absorb. |
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Hydrolysis/Hydrolyze |
A reaction with water that splits the water molecule into Hydrogen and Hydroxide ions |
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Active acidity |
Determines if there is Hydrogen and Aluminum in the soil solution by pH measurement |
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Exchangeable Acidity |
Hydrogen and Aluminum elements in the soil solution that are held up as exchangeable cations on soil colloids. Determined by cation exchange. |
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Residual Acidity |
Hydrogen and Aluminum that are in non-exchangeable forms on soil colloids. That are determined by pH buffered extractant |
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Buffering Capacity |
The ability of a soil to resist changes in pH. Commonly determined by presence of clay, humus, and other colloidal materials |
