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AGR 345 Soil Science > Test 3 Review > Flashcards

Test 3 Review Flashcards

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1
Q

soil texture

A

proportion of sand, silt, and clay in the soil

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2
Q

soil structure

A

arrangement or grouping of individual soil particles into peds or aggregates

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3
Q

soil particles

A

sand, silt, clay

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4
Q

factors that influence bulk density (5)

A
  1. organic matter
  2. texture/aggregation
  3. structure
  4. compaction
  5. depth in soil profile
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5
Q

how to increase soil pH

A

lime

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6
Q

soil water at field capacity

A

saturated and allowed to drain freely

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7
Q

pedon

A

smallest unit of soil that contains all the horizons of a specific soil type

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8
Q

catena

A

a sequence of soils with different horizons caused by differences in their depth to the water table

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9
Q

soil profile

A

2-D representation of a vertical section of soil from the surface to deepest layers

whole thing from top to bottom

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10
Q

soil horizon

A

soil layers; roughly parallel layers in the soil with varying compositions and properties

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11
Q

soil color determinants (4)

A
  1. mineralogy of parent material
  2. organic matter
  3. hydrology
  4. soil chemistry
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12
Q

tool to determine soil color

A

Munsell Color Chart

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13
Q

10YR 6/3

A

10YR = hue
6 = value
3 = chroma

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14
Q

hue

A

proportions of red to yellow

top right corner

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15
Q

chroma

A

how bright vs dull

x-axis

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16
Q

value

A

amount of light reflected

y-axis

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17
Q

amount of soil nutrients

A

at least 16

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18
Q

amount of soil macronutrients

A

9

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19
Q

amount of soil micronutrients

A

8

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20
Q

fertile and infertile soil based on CEC, soil pH, silicate clay type

A

fertile: higher CEC, neutral pH, and montmorillonite silicate clay

infertile: low CEC, highly acid or highly alkaline pH, Fe and Al oxide silicate clays

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21
Q

in what pH range are N and P available for plants

A

5.8 - 6.8 (K tends to like more alkaline soils)

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22
Q

molybdenum is usually important for what crop?

A

soybeans (rhizobium) and legumes

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23
Q

in what pH range is molybdenum usually available for plants?

A

alkaline soils (pH 7.1+)

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24
Q

lime commonly comes in two forms, CaCO3 and MgCO3, what are their common names?

A

Ca: calcite
Mg: dolomite

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25
Q

decreasing pH =

A

sulfur
- potassium sulfate
- anything sulfate (SO4)

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26
Q

classifications of soil organisms

A
  1. macrofauna
  2. microfauna
  3. flora
  4. food - herbivores, detritivores, predators
  5. based on O2 demand - aerobic and anaerobic
  6. based on energy and C source - autotrophic and heterotrophic
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27
Q

producers

A

create their own food through photosynthesis (plants)

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28
Q

consumers

A

eat other organisms for energy (can’t make their own)

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29
Q

detritus

A

decaying organic matter

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30
Q

decomposers

A

have the ability to break down organic material releasing useful nutrients

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31
Q

heterotrophs

A
  • heterotrophic from breakdown of OM (carbon)
  • most numerous
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32
Q

immobilization

A

microbes absorb nutrients from the soil, making them unavailable for plant use

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33
Q

mineralization

A
  • the conversion of soil organic matter to plant available nitrogen
  • the release of nitrogen from the organic form to the inorganic form
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34
Q

nitrification

A

nitrifying bacteria convert ammonia (NH3) to nitrate (NO3)

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35
Q

denitrification

A

wet soil, lack of aeration, and leaching of N because of water

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36
Q

compaction causes the loss of what primary nutrient

A

nitrogen

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37
Q

nitrogen fixation

A

converting atmospheric N into usable forms

N2 -> NH4

algae: wetland
bacteria: legumes

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38
Q

role of bacteria

A
  • nitrification
  • nitrogen cycle
  • improve soil structure
  • decomposing OM
  • degrading pollutants
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39
Q

role of algae

A
  • producer in aquatic systems
  • oxygen production
  • carbon sequestration
  • water purification
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40
Q

role of earthworms (3)

A
  1. soil fertility by producing cast
  2. reduce erosion and improve aggregate stability
  3. aeration and drainage
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41
Q

rhizobium

A

nitrogen producing bacteria found on root nodules on legumes

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42
Q

mycorrhiza

A

fungi that infect the plant roots of nearly all plants

benefits include plant nutrition (especially P), drought tolerance, disease resistance, and soil structure improvement

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43
Q

types of mycorrhiza and roles

A
  1. endomycorrhizae - agriculture
  2. ectomycorrhizae - forest
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44
Q

various functions of microorganisms in soil

A

nitrogen cycling

45
Q

what is soil organic matter

A

the debris of biological activity in soil

every organic compound that is in soil, which includes roots, animals, and microorganisms

46
Q

what are the components of soil organic matter

A

humus and active organic matter

47
Q

why is SOM important for soil fertility

A

produces N, P, and S and can hold additional nutrients

very good for P

48
Q

what nutrients are released during soil organic matter decomposition?

A

N, P, S, Ca, and Mg???

49
Q

common percentage of OM in mineral soils

A

very low = 1%
average = 2-4%
high = >5%
KY = 1-3%

50
Q

common percentage of OM in organic soils

A

greater than 20%

51
Q

importance of C/N ratio in plant residues as related to N availability for plants

A
  • soil microbes require C to build organic compounds and for energy
  • soil microbes need N to produce amino acids, protein enzymes, and DNA
  • microorganisms compete for soil N
  • helps determine the rate of decay and the availability of N to plants
52
Q

C/N ratios in soil

A

8:1 to 15:1 or 20:1

53
Q

C/N ratios in microorganisms

A

5:1 to 10:1

54
Q

C/N ratios in plant residues

A

24:1ish

55
Q

C/N ratios in sawdust

A

400:1 to 600:1

56
Q

macronutrients

A

needed in large amounts

57
Q

macronutrients examples

A

C, H, O, N, P, K, Ca, Mg, S

58
Q

micronutrients

A

needed in small amounts

59
Q

micronutrient examples

A

Mn, Cu, Zn, Mb, B, Cl, Fe

60
Q

non-mineral elements

A

carbon, hydrogen, oxygen

61
Q

what forms of N are available for plants

A

NO3- and NH4+

62
Q

what forms of P are available for plants

A

H2PO4- and H2PO4-2

63
Q

what forms of K are available for plants

A

K+

64
Q

functions of N

A
  1. promotes growth of leaves and stems
  2. dark green color; chlorophyll
  3. amino acids and proteins
65
Q

N deficiency symptoms

A
  • sick, yellow-green color
  • short stems, small leaves, pale colored leaves and flowers
  • slow and dwarfed plant growth
66
Q

functions of P

A
  1. stimulates early formation and growth of roots
  2. ADP -> ATP
  3. fast and vigorous growth
  4. stimulates flowering and seed development
  5. needed for the enzyme action of many plant processes
67
Q

P deficiency symptoms

A
  • decrease in growth
  • slow maturity
  • older leaves turn purple in color
68
Q

functions of K

A
  1. form carbohydrates and proteins
  2. form and transfer of starches, sugars, and oils
  3. increases disease resistance, vigor, and hardiness
  4. water regulation
69
Q

K deficiency symptoms

A
  • mottled, spotted, streaked, or curled leaves
  • scorched, burned, dead leaf tips and margins
70
Q

functions of Ca

A
  1. improves plant vigor
  2. influenced intake and synthesis of other plant nutrients
  3. important part of cell walls
71
Q

Ca deficiency symptoms

A
  • small developing leaves
  • wrinkled older leaves
  • dead stem tips
72
Q

functions of Mg

A
  1. influences the intake of other essential nutrients
  2. helps make fats
  3. assists in translocation of phosphorus and fats
73
Q

Mg deficiency symptoms

A
  • interveinal chlorosis (yellowing of leaves between green veins)
  • leaf tips curl or cup upward
  • slender, weak stalks
74
Q

functions of S

A
  1. root growth and vigorous vegetative growth
  2. essential to protein formation
75
Q

S deficiency symptoms

A
  • young leaves are light green with lighter colored veins
  • yellow leaves and stunted growth
76
Q

why is CEC important for crop production

A
  • influences the quantity of plant nutrients held and made available in the soil
  • soils with high CEC hold more nutrients and are better able to buffer rapid changes in the soil solution
77
Q

why is % base saturation important for crop production

A
  • indicates the balance of essential plant nutrients in the soil relative to acidic cations
  • impacts soil pH and nutrient availability
78
Q

fertilizer grade

A

represented by three number that correspond to the percentage of weight of N, P2O5, and K2O

ex. 15-5-15

79
Q

fertilizer ratio

A

the relative amount of nitrogen, phosphate, and potash in fertilizers

ex. 3-1-3

80
Q

K -> K2O

A

%K x 1.2

81
Q

K2O -> K

A

%K2O / 1.2

82
Q

P -> P2O5

A

%P x 2.29

83
Q

P2O5 -> P

A

%P2O5 / 2.29

84
Q

N fertilizers

A
  • ammonium nitrate
  • ammonium sulfate
  • anhydrous ammonia
  • urea (45%)
85
Q

P fertilizers

A
  • ammonium phosphate
  • diammonium phosphate
  • potassium phosphate
  • dipotassium phosphate
  • phosphoric acid
86
Q

K fertilizers

A

potash is used for preparation of potassium sulfate and potassium nitrate

87
Q

6 different types of fertilizers

A
  1. complete
  2. incomplete
  3. organic
  4. inorganic
  5. soluble
  6. insoluble
88
Q

7 different fertilizer application methods

A
  1. banding
  2. sidedressing
  3. topdressing
  4. perforating
  5. broadcasting (oldest way)
  6. foliar spraying
  7. fertigation
89
Q

organic fertilizer

A

comes from plant or animal matter and contains carbon compounds

90
Q

inorganic fertilizers

A

chemical fertilizers

91
Q

soluble fertilizer

A

dissolve in water and applied as a liquid solution (fertigation)

92
Q

insoluble fertilizer

A

granular and slow release

93
Q

what causes the wet dirt smell?

A

actinomycetes

94
Q

fungi has _______ and ________ that help form and build organic matter

A

hyphae and mycelium

95
Q

higher C/N ratio =

A

nutrients are more immobile

96
Q

sawdust has the _______ C/N ratio and can harm plants because of _________ _______.

A

highest; microbial feeding

97
Q

a lower C/N ratio promotes…

A

mineralization and plant availability

98
Q

ammonia is _____ and ___ _______ to plants, instead it…

A

toxic and not available; goes to the atmosphere and causes N losses

99
Q

volatilization

A

NH4 -> NH3 during high temperatures with good aeration

100
Q

NO3 -> N2O -> N2 in wet soil with poor aeration

A

denitrification

101
Q

microbes love what form of N?

A

N2

102
Q

NO3 loss: down and horizontal

A

down = leaching
horizontal = erosion/runoff

103
Q

functions of Mn

A

plant metabolism and N transformation

104
Q

functions of Cu

A

helps with respiration and use of Fe

105
Q

functions of Zn

A

plant metabolism, helps form growth hormones, reprodution

106
Q

functions of B

A

water absorption by roots and translocation of sugars

107
Q

functions of Cl

A

essential to some plant processes and acts in enzyme systems

108
Q

functions of Fe

A

chlorophyll production

AGR 345 Soil Science (3 decks)

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