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PLS 366 > Definitions > Flashcards

Definitions Flashcards

1
Q

topsoil

A

organically enriched, majority of plant roots found here

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2
Q

subsoil

A

where most water is stored, roots can’t really grow here, it’s hard to modify subsoil

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3
Q

disintegration caused by temperature, water, wind, ice, and organisms.

A

physical weathering

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4
Q

> 0.08 mm diameter, earthworms and small organisms can move through, water can move through

A

macropores

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5
Q

< 0.08 mm diameter, hold water so tightly plants can’t access it

A

micropores

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6
Q

the hydrogen don’t attach to the water evenly, they make a v-shape instead and this causes the positive charges to cling towards the side weighed down with the two hydrogens therefore causing this property of water

A

polarity

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7
Q

one of the hydrogens makes a low-energy bond to an oxygen particle from another molecule of water. this causes water to have a higher boiling point, specific heat, and viscosity

A

hydrogen bonding

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8
Q

the attraction of water molecules for each other

A

cohesion

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9
Q

the attraction of water molecules for solid surfaces, causes some water molecules to be held rigidly at the surface of soil solids

A

adhesion

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10
Q

results from the greater attraction of water molecules for each other than for the air above, causes an inward force at the surface

A

surface tension

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11
Q

force caused by adhesion, reduced the energy state of water near particle surfaces

A

Matric

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12
Q

force caused by cohesion, reduces energy state of water in the soil solution

A

osmotic

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13
Q

force pulling the water downward

A

gravimetric

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14
Q

process by which water enters the soil pore spaces and becomes soil water, takes place at the soil surface

A

infiltration

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15
Q

process by which water moves downwards into the soil profile, rate is related to the soil’s hydraulic conductivity

A

percolation

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16
Q

when water addition stops the largest pores will drain downward rapidly, when this flow becomes negligible the soil is holding the maximal amount of water useful to plants

A

field capacity

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17
Q

all soil pores are filled with water, matric potential is close to zero, the soil will remain here only so long as water continues to infiltrate

A

maximum retentive capacity

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18
Q

the rate of plant water removal fails to keep up with the plant needs so the plant wilts

A

wilting coefficient

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19
Q

soil moisture is lowered below the wilting point, the water molecules that remain are very tightly held, most are absorbed by colloidal soil surfaces the water is held so rigidly that most of it can only move in the vapor phase

A

hygroscopic coefficient

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20
Q

an area of land drained by a single system of streams and bounded by ridges that separate it from adjacent watersheds

A

watershed

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21
Q

how water is returned to the atmosphere

A

Evaporation

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22
Q

after plant use it is vaporized from the stomata on the surfaces of the plant leaves

A

transporation

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23
Q

precipitation is intercepted by plant foliage and returned to the atmosphere by evaporation without ever touching soil

A

interception`

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24
Q

the physical condition of the soil in relation to plant grown

A

tilth

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25
Q

Name three primary properties used to delineate soil horizons

A

color, texture, structure

26
Q

soil solids approximate this percentage of a loam at field capacity

A

50%

27
Q

ions freely available for absorption by plant roots are found in this fraction

A

soil solution fraction

28
Q

essential to plant respiration at interface of pedosphere and atmosphere

A

O2

29
Q

degradation of OM from plant residues is considered this type of soil profile developmental process

A

transformation

30
Q

limestone PM weathers into this bivalent cation which is an example of what kind of weathering

A

chemical Ca2+

31
Q

name the five soil forming factors

A

time, biota, parent material, topography, climate

32
Q

soils with equal amounts of each texture would be in which textural class

A

clay loam

33
Q

most weathered soil order

A

oxisol

34
Q

example of a clay mineral with extensive isomorphous substitution

A

smectite

35
Q

a 1:1 silicate clay mineral

A

kaolinite

36
Q

pH dependent charge, edge charges

A

kaolinite

37
Q

vertisols are dominated by what types of charges

A

permanent charge

38
Q

oxisols are dominated by what type of charge

A

pH dependent charge

39
Q

clay with largest surface area

A

smectite, 2:1 w/ interlayer

40
Q

what makes the water stay up in the fine textured stuff

A

matric potential (surface)

41
Q

how does water move?

A

wet to dry, high to low potential, and macropores to micropores

42
Q

highest capillary rise ultimately?

A

clay

43
Q

smallest radius means

A

greatest height

44
Q

how do you interpret the trends in ksat data with soil depth

A

it decreases with depth because there is higher clay that slows water movement because it’s mostly micropores that just hold the water

45
Q

range in soil water potential that defines the water available to plant roots

A

wilting point and field capacity

46
Q

soil structure most prevalent in a C horizon

A

massive

47
Q

soil structure most prevalent in a B horizon

A

blocky

48
Q

soil structure most prevalent in a E horizon

A

platy

49
Q

this soil separate is .05 to .002 and not gritty

A

silt

50
Q

way to increase soil temperature

A

plastic and organic mulches

51
Q

three factors responsible for soil aeration

A

soil macroporosity, soil water content, O2 consumption

52
Q

when temperature rises, what happens to microbial activity?

A

doubles for ever 10 degree increase

53
Q

next terminal electron acceptor when there is no longer any O2

A

NO3

54
Q

Name the four soil forming processes

A

additions, losses, transformations, translocations

55
Q

translocation

A

Movement of soil constituents (organic or mineral) within the profile and/or between horizons.

56
Q

transformations

A

The chemical weathering of sand and formation of clay minerals, transformation of coarse OM into decay resistant organic compounds (humus)

57
Q

losses

A

Through the movement of wind or water, or uptake by plants, soil particles (sand, silt, clay, and OM) or chemical compounds can be eroded, leached, or harvested from the soil, altering the chemical and physical makeup of the soil.

58
Q

additions

A

Materials added to the soil, such as decomposing vegetation and organisms (organic matter–OM), or new mineral materials deposited by wind or water.

59
Q

what is the charge of O?

A

-2

60
Q

what is the charge of H?

A

+1

PLS 366 (11 decks)

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