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Soil Science > Unit 3 > Flashcards

Unit 3 Flashcards

1
Q

What number range does the pH scale follow?

A

0-14

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2
Q

If something has a pH between 0-6, it is…

A

acidic

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3
Q

if something has a pH between 8-14, it is…

A

basic

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4
Q

if something has a pH of 7, it is…

A

neutral

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5
Q

2 ways to determine soil pH:

A

pHw: water suspension test.. water measures H+ ions attached to soil

pHs: lab field kit

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6
Q

4 ways that pH governs productivity:

A
  1. Nutrient Availability
  2. Strong acidic soils have low CEC occupied by K, Mg, &Ca
  3. Affects pesticides
  4. Affects microbial activity
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7
Q

Factors causing pH to change? (9)

A
  1. Depletion of bases by erosion
  2. Amount of rainfall/percolation
  3. Absorption of bases by plants
  4. chemical fertilizers
  5. tillage
  6. acid rain
  7. waste & sewage sludge
  8. irrigation
  9. plant roots
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8
Q

What is buffer capacity?

A

The resistance of the soil to changes in pH

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9
Q

what is active acidity?

A

H ions in solution

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10
Q

What is reserve acidity?

A

Absorbed H+ & Al+

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11
Q

Reserve acidity depends on…

A

the higher the CEC, the greater the buffer capacity

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12
Q

Why correct soil pH? (acidic levels)(5)

A
  1. Elements can reach toxic levels (deadly)
  2. Microbial activity and population will be low
  3. Ca & Mg may be deficient
  4. Lose more potassium
  5. low pH can mobilize heavy metals (deadly)
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13
Q

POSSIBLE TEST QUESTION: If on a budget, what should you fix before adding nutrients?

A

pH

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14
Q

Liming materials

A 
Calcitic Limestone
Dolomitic Limestone
Burned Lime: Made by heating limestone
Hydrated Lime: Burnt lime with water added
Marl: freshwater deposit in swamp areas
Ground seashells
Lime-rich industrial waste
wood ash
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15
Q

What is burned lime?

A

a liming material made by heating limestone

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16
Q

what is hydrated lime?

A

burnt lime with water added

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17
Q

what is marl?

A

freshwater deposit in swamp areas

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18
Q

Quantities of lime are determined by?:

A

Current pH
Desired pH
Buffer capacity
chemical makeup and fineness of liming material used

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19
Q

5 factors influencing liming frequency?

A
  1. soil texture
  2. rate of N fertilization
  3. rate of crop removal
  4. amount of lime applied
  5. pH desired range
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20
Q

When is the best time to lime? (2)

A
  1. soil test for lime needed every 3 years

2. 3-6 mos. before planting legumes

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21
Q

What is ENM?

A

Effective Neutralizing Method

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22
Q

ENM tells us

A

how many tons per acre of material to apply

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23
Q

ENM on soil test says 850, quarry has calculated ENM to be 475…. how much per acre needs to be applied?

A

850/475=1.78 tons per acre

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24
Q

Alkaline soils have a pH above…

A

7

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25
Q

What is a saline-sodic soil?

A

high levels of both soluble salts and sodium

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26
Q

what is a sodic soil

A

mostly sodium, called black alkali or slick spots

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27
Q

what is a saline soil?

A

mainly chlorides and sulfates of Ca, Na, Mg, and K

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28
Q

Causes of alkaline soils (3)

A
  1. minimal leaching
  2. carbon dioxide and carbonates precipitate
  3. the amount of Na + Ca ions in the soil
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29
Q

About ____ of the soils in the USA are affected by salinity

A

1/3

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30
Q

Measuring salinity in 2 ways…

A

Total dissolved solids (TDS)

Electrical conductivity: the more salts in solution, the more current can be passed between them

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31
Q

Problems associated with alkaline soils (4)

A
  1. Nutrient deficiencies
  2. CEC levels tend to be higher
  3. Calcium Rich Layer (duripan)
  4. water supply —-> dry soils
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32
Q

2 ways to reclaim a saline soil

A

irrigate and attempt to leach

gypsum

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33
Q

Soil microorganism groups (5)

A
  1. Macrofauna
  2. Macroflora
  3. Microfauna
  4. Microflora
  5. Mesofauna
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34
Q

What is functional resiliency in a soil?

A

There are several organisms that carry out similar tasks

more overlapping microbes=more stable and resilient

35
Q

4 examples of macrofauna:

A

gophers, ants, mice, beetles

36
Q

2 broad examples of macroflora:

A

Mosses and vascular plants

37
Q

3 examples of mesofauna:

A

mites, springtails, worms

38
Q

5 primary producers:

A
  1. vascular plants
  2. mosses
  3. lichens
  4. algae
  5. photosynthesizing bacteria
39
Q

3 primary consumers

A
  1. herbivores
  2. saprophytes
  3. detritivores
40
Q

what is an herbivore

A

a plant eater

41
Q

what is a saprophyte

A

organism that lives on dead material (fungi)

42
Q

what is a detritivore?

A

an ANIMAL that feeds on dead material

43
Q

Secondary consumers:

A

Predators-carnivores

Microbivore feeders

44
Q

Tertiary consumers

A

Feed on secondary consumers: moles, robins, ants, spiders, mites

45
Q

there are over ___ different genera of bacteria

A

200

46
Q

POSSIBLE TEST QUESTION: what is the role of bacteria in the soil?

A

Breakdown!

47
Q

5 types of bacteria

A
  1. arthrobacters
  2. streptomycetes
  3. pseudomonas
  4. sporulating bacilli
  5. cyanobacteria
48
Q

what bacteria is predominant in the soil?

A

arthrobacters

49
Q

What bacteria gives soil a smell?

A

streptomycetes

50
Q

What bacteria is used in pesticides?

A

pseudomonas

51
Q

which bacteria fix Nitrogen?

A

sporulating bacilli

52
Q

which bacteria contain chlorophyll?

A

cyanobacteria

53
Q

what is the rhizosphere?

A

millimeter of soil closest to the root surface

54
Q

The rhizosphere is the most…

A

biologically active area in the soil

55
Q

Plants produce the ____ that microbes feed on

A

organic matter

56
Q

there are over ______ species of nematodes

A

15,000

57
Q

Are nematodes exclusively good or bad?

A

no. there are good and bad nematodes. can be parasitic or free living

58
Q

what do nematodes do?

A

consume bacteria, important for the release of N in the soil

59
Q

Fungi are important in…

A

humus formation, nutrient cycling, and stabilizing soil aggregates.

60
Q

Fungi produce…

A

penicillin and mycotoxins

61
Q

6 types of fungi

A
  1. acraciomycetes
  2. myxomycetes
  3. flagellated fungi
  4. sugar fungi
  5. higher fungi
  6. imperfect fungi
62
Q

Mycorrhizae are

A

a fungi that grow in a symbiotic relationship with a plant

63
Q

advantages of mycorrhizae (2)

A

extends root zone

puts nutrients in a plant available form

64
Q

what is bioremediation?

A

using microorganisms to convert organic contaminants to less harmful products

65
Q

what 3 points are on the disease triangle?

A

susceptible host, pathogen and favorable environment.

a disease cannot exist without all 3

66
Q

functions of o.m. (3)

A

nutrient and water storage
soil aggregation–resist compaction
prevent erosion

67
Q

Labile means

A

easy to decay material: starches, cellulose, hemicellulose

68
Q

recalcitrant means:

A

difficult to decay material: lignin

69
Q

Process of decay (4)

A

solution
fragmentation
decay
humification

70
Q

solution is…

A

nutrients dissolving out of litter into nearby soil water

71
Q

Fragmentation

A

shredding up and breaking up

72
Q

Decay

A

labile material broken down by microbes

recalcitrant slowly broken down by fungi

73
Q

Humification

A

Occurs when N is released from labile decay and re-used to break down C

74
Q

Humus has…

A

50% C and 5 % N

75
Q

Humus has a C:N ration of

A

10:1

76
Q

Humus is ____ in color and ____ to decay

A

dark in color, resistant to decay

77
Q

factors affecting O.M. (5)

A

Vegetation, climate, soil texture, drainage, tillage

78
Q

Prairies generate the most ____ __

A

soil O.M.

79
Q

Fine textured soils have more _____ than coarse textured soils

A

O.M.

80
Q

Poorly drained soils have _____ ____

A

more O.M.

81
Q

Decay is a primarily ____ process

A

aerobic

82
Q

Decay is influenced by (4)

A
  1. tillage
  2. amount of water
  3. amount of life organisms
  4. structure and texture
83
Q

2 undesirable effects of O.M.

A
  1. N can be tied up

2. some plant residues are toxic to other plants (phytotoxins)

84
Q 
What happens to soil organic matter decomposition when you...
add mulch?
clear cut?
no till into corn stover?
Use hairy vetch as a green manure crop?
A

add mulch?….. slows dow
clear cut?……… speeds up @ first then slows down
no till into corn stover?…… slows down
Use hairy vetch as a green manure crop?…… speeds up

Soil Science (5 decks)

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