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Soils > Soil properties > Flashcards

Soil properties Flashcards

1
Q

What direct effect does color have on behavior or use of soil?

A

Soil warming in spring (the darker the soil the faster it warms)

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2
Q

Importance of soil color

A

Provides valuable clues to the nature of other soil properties (as well as classification)

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3
Q

Hue

A

Designates the color (number on top of page)

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4
Q

Value

A

designates the lightness of color (number on side of page)

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5
Q

Chroma

A

Distinguishes pure hue from a gray shade (number on bottom of page)

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6
Q

Main factors influence on soil color

A
  1. Water content
  2. Organic matter
  3. Oxidation state of iron and manganese/Magnisum
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7
Q

Black - Dark Brown (10Yr 2/1)

A

High organic matter

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8
Q

Reds and yellows

A

Ferric Iron (Fe^3+) oxides and hydroxides

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9
Q

Hematite

A

red (intense weathering) (5R 3/6)

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10
Q

Goethite

A

Yellowish brown (10YR 8/6)

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11
Q

Limonite

A

Yellow (humid environments)

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12
Q

Ferrihydrite

A

dark red (2.5 YR 3/6)

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13
Q

Gray and Bluish

A

Reduced iron compounds and poorly drained soils

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14
Q

Black (10YR 2/1) (Little Organic material)

A

Manganese Oxides

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15
Q

Greenish

A

Glauconite

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16
Q

White/Gray (10YR 6/1)

A

Quartz and silicate minterals

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17
Q

Whites (10YR 8/2)

A

Carbonate accumulation calcites, and soluble salts

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18
Q

How does chemical reduction affect soil color and under what conditions does it occur?

A

ferric iron oxides to mobile ferrous iron

results in gray colored soils

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19
Q

Why is texture considered a “basic soil property”?

A

does not change

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20
Q

Relationship between particle size and surface area

A

Larger particle = lower surface area

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21
Q

What does soil surface area influence in the soil?

A

Water holding capacity, chemical reactions, soil cohesion, cation exchange capacity, ability to support microorganisms

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22
Q

Teton dam

A

Failure to pay attention to soil properties. Seepage of water into an area with poor sealing like sand or silt.

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23
Q

Aggregates

A

Sand, silt, and clay particles when they are not independent of each other

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24
Q

Microaggreates

A

Comprised of smaller particles (2-250 micrometers)

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25
Q

Macroaggregates

A

larger (.25-5mm) comprised of microaggregates

26
Q

Peds

A

Large-scale structure evident when observing soil profile

27
Q

Granular

A

-spherical aggregates
-loosely packed together
-typically high in organic matter
-very porous
-often observed in A horizons
-susceptible to rapid changes

28
Q

Blocky

A

-irregular and cubelike
-molded by shape of surrounding blocks
-common in B horizon in humid regions
(angular and sub angular)

29
Q

prismlike

A

-pillarlike
-up to 150mm
-swelling clays
-b horizon
-arid regions
(columnar and prismatic)

30
Q

platy

A

-thin sheets
-caused by soil forming process or PM
-compaction
-lower porosity

31
Q

Block density

A

mass of a unit volume of dry soil

32
Q

factors that affect bulk density

A

-texture
-Organic matter
-type of material
-compaction

33
Q

What bulk density inhibits root growth

A

above 1.6 g/cm^3

34
Q

Equation for bulk density

A

Db= mass soil/bulk soil volume

35
Q

What typically has the greatest bulk density?

A

Sand

36
Q

Least amount of bulk density

A

clay

37
Q

Particle density

A

Mass per unit volume of soil solids

38
Q

Factors that affect particle density

A

-type of mineral present
-organic matter content

39
Q

Average particle density in mineral soils

A

2.65

40
Q

Exceptions for average particle density

A

soils with high O.M
Very sandy or clayey soils

41
Q

Particle density equation

A

Dp= mass soil/volume of soil solids

42
Q

Benefits of tillage

A

-break large clods into aggregates
-incorporate organic material
-kills weeds

43
Q

disadvantages of tillage

A

-accelerate decomposition of OM
-compaction

44
Q

Plow pans

A

Dense zones immediately below plow layer (increases bulk density and restricts root growth)

45
Q

Ways to reduce compaction

A

-decrease tillage
-use wider wheels
-minimize operations on wet soils
- use rotations with deep-rooting crops

46
Q

Porosity

A

the total volume percentage of the bulk density that is not occupied by soil particles (air and water and plant)

47
Q

pore space equation

A

% pore space= 100- (Db/Dp * 100)

48
Q

Macropores

A

-Allow rapid movement of water/air into or through soil
-large enough to accommodate plant roots and small organisms

49
Q

micropores

A

-do not allow air movement
-usually filled with water in field soils
-water movement through micropores is slow
-some pores are too small for bacteria

50
Q

when is pore size more important than total pore volume

A

soil drainage and aeration

51
Q

effect of cultivation on pore space

A

reduces pore space and pore size

52
Q

Soil aggregates

A

many soil particles held in a single mass or cluster, such as a clod, crumb, block or prism

53
Q

Primary mechanism of soil particles being held together

A

held together by clay or organic matter

54
Q

psuedosand

A

clay and iron oxides held together forming a stable aggregate

55
Q

What if a more weakly charged ion such as sodium (Na+ or K+) is present with few divalent or trivalent ions?

A

-clays will not stick together
-not good for plant production
-common in arid regions

56
Q

Earthworms form _____ after ingesting soils

A

casts

57
Q

what form sticky networks to bind particles together?

A

Plant root hairs and fungal hyphae

58
Q

Microorganisms create

A

organic glues

59
Q

Soil tilth

A

the physical condition of soil in relation to plant growth

60
Q

Soil tilth is influenced by

A
  • aggregate formation and stability
    -bulk density and pore space
    -soil moisture
    -soil texture
61
Q

Soil crusting

A

develop when sealed over soil surface dries out after rainfall or irrigation

62
Q

proctor test

A

simple way to evaluate how compact you can get a soil and what content you want

Soils (6 decks)

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