Term
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Definition
Series showing strength of cation attraction relative to pH
Al(3+)>Ca(2+)>Mg(2+)>K(+)=NH4(+)>Na(+)
Strongest Held-----------Weakest Held |
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Term
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Definition
Shows how much moisture in soil expressed as a volume of water in a cubic meter(or cm)
((Vwater)/(Vsoil))x100 |
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Term
| Gravimetric Water Content |
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Definition
A measure of amount of water in a soil, based on mass.
((mass of wet soil)-(mass of dry soil))/(mass of dry soil) |
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Term
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Definition
Caused by waters attraction to other things causes water to rise against gravity
h=(.15/r) |
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Definition
| Measure of waters attraction to solid surfaces, always negative water moves from high energy (wet soil) to low (dry soil) if Pmatric=0 soil is saturated |
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Term
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Definition
| Measure of potential of water to move due to gravity, based off some chosen reference point, usually lower so the potential is positive |
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Term
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Definition
| Measure of the part of soil water potential that is affected by presence of solutes, more solutes = lower potential |
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Term
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Definition
| Amount of water the soil will hold against gravity naturally (soak the soil then let excess drain off remaining is FC)usually -10<-33 kPa |
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Term
| Permanent Wilting Point (PWP) |
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Definition
| PWP is the point at which water is held so tightly to clay surfaces plants can no longer extract water and die <-1500kPa |
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Term
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Definition
| The point at which soil is physically not able to hold any more water (when Pmatric=0) 0kPa |
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Term
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Definition
| Instrument used to measure soil water potential, consists of porous cup connected to vacuum doesn't let air in |
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Term
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Definition
| Cations of LOWER charge may substitute for HIGHER charge cations during mineral formation, always - charge usually found in 2:1 layer silicates |
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Term
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Definition
Found in all clays,charge changes with soil pH
low pH= + charge
high pH= - charge |
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Term
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Definition
| An organic or inorganic clay with a ratio of 1 octahedral and 1 tetrahedral layer this creates a very tight bond not letting much iso sub happen |
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Term
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Definition
| Ratio of 2 tetrahedral and 1 octahedral layers, much more common with iso sub |
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Term
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Definition
Intense weathering, pH dependant charge Negative charge above 5-7 pH
Positive charge below 5 pH
No charge in 5-7 pH |
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Term
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Definition
Stable organic "residue" from breaksown of org matter, greatly affected CEC
almost always - charge is pH above 3 |
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Term
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Definition
| Things in between the layers in a crystalline structure (example K+ in between layers in Kaolinite) |
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Term
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Definition
| Any particle with a high surface area/mass ratio and is less than .002 mm |
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Term
| Silicon Tetrahedral Layer |
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Definition
| Combined with Al octahedral layer in 2:1 and 1:1 proportions to make crystalline structure looks like Si pyramids. |
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Term
| Aluminum Octahedral Layer |
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Definition
| Combined with Si Tetrahedral layer in 2:1 and 1:1 proportions to make crystalline structure looks like 2 pyramids stacked base to base |
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Term
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Definition
| Movement of gas particles due to concentration gradient, moves from more gas particles to less until all areas have equal ratios, much slower through water (explains organic buildup in histosols) |
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Term
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Definition
| movement of gasses due to differences in pressure, not as important as diffusion |
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Term
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Definition
| Soils that have been exposed to anaerobic conditions for long time (waterlogged histosols) may have switched to anaerobic respiration using N2 |
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Term
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Definition
Measure of total Neg charge available to attract + cations
Low CEC=highly weathered= not much - charge
High CEC=2:1 Silicates or Organic Matter (Humus) |
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Term
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Definition
| The ability of soil to resist a pH change, determined by colloidal fraction (clay%) and CEC |
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Term
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Definition
| A reaction involving reduction (gain electrons reduce charge) and oxidation (lose electrons gain charge) |
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Term
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Definition
| The proportion of soil mass over soil volume |
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Term
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Definition
| The percent of space taken up by soil pores =100-((Bulk density)/(Particle density or 2.65g/cm^3))*100 |
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Term
| Plant Available Water (PAW) |
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Definition
| FC-PWP=PAW the amount of water held naturally - permanent wilting point = plant avail water |
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Term
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Definition
| The amount of light reflected by a soil ranges from .1(dark colored soil) to .5(light) |
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Term
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Definition
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Term
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Definition
| Basic formula for all life (Sugar+Water+Oxygen)=(Water energy and carbon dioxide) |
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Term
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Definition
| Measure of tendency of something to become oxidized or reduced (tendency of electrons to move) |
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Term
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Definition
| A 1:1 Silicate clay, very stable and nonreactive,little-no weathering, H bonding makes bond too tight for iso sub, very low CEC, small pH charge |
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Term
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Definition
| A 2:1 layer silicate clay, more weathered than illite, iso sub in Tetra sheet, High CEC |
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Term
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Definition
| 2nd level weathering, more than kaolinite, iso sub in tetra sheet, medium CEC, K+ in inter-layers binds layers together preventing swelling |
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Term
| Montmorillionite (Smectite) |
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Definition
| Very expandable 2:1 layer silicate, most weathered, a lot of iso sub and high CEC |
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