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Soils > Soils Test 3 > Flashcards

Soils Test 3 Flashcards

1
Q

essential plant nutrient

A

required for plants to live

minimum nutrients for survival

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2
Q

16 essential plant nutrients

A

C HOPKNS CaFe Mn B Mg CuZn Mo Cl

c hopkns cafe managed by my cousin mo clyde

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3
Q

primary nutrients

A

N, P, K

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4
Q

secondary nutrients

A

Ca, Mg, S

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5
Q

nutrients from water and atmosphere

A

C from atmospheric CO2

H and O from water

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6
Q

micronutrients

A

all others (Fe, Mn, B, Cu, Zn, Mo, Cl)

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7
Q

N ions

A

NO3- (anionic)

NH4+ (cation)

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8
Q

P ions

A

H2PO 4-
HPO4 2-
(both anionic)

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9
Q

K ions

A

K+ (cation)

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10
Q

Ca ions

A

Ca2+ (cation)

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11
Q

Mg ions

A

Mg2+ (cation)

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12
Q

S ions

A

SO4 2- (anionic)

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13
Q

4 mechanisms by which soil nutrients transfer from soil to plants

A

mass flow-sucked up through water
root interception-roots in contact with nutrient
ion exchange on colloidal regions
simple diffusion-random movement

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14
Q

Importance of N to crop yields

A

number one primary nutrient needed in plants
easiest of the nutrients that can be lost
increases crop yields
most limiting for plant growth

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15
Q

3 main functions of N in plants

A

component of chlorophyll for photosynthesis
component of nucleic acids which form DNA, RNA
essential element of all amino acids

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16
Q

Healthy plants contain how much N

A

2.5-4%

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17
Q

Deficiency symptoms of N and S

A

leaves pale yellowish green in color

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18
Q

5 inputs of N into plant root zone

A 
biological N2 fixation (legumes)
industrial fixation (N fertilizers)
lightning oxidation (N2 to NO3-)
organic matter decomposition
animal wastes
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19
Q

5 losses of N from the root zone of crops

A 
crop removal
NH3 volitilization
denitrification
leaching
physical removal (erosion, land grading, etc)
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20
Q

N mineralization

A

converting organic nitrogen from organic matter into inorganic nitrogen (ammonia or ammonium) due to microbial activity

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21
Q

N immobilization

A

converting inorganic nitrogen into organic. (opposite mineralization)

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22
Q

SON

A

soluble organic nitrogen
new findings
nobody really knows the makeup of this yet

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23
Q

Ammonium fixation by clay minerals

A

layers of clay swell when hydrated. Ammonium can drift in between layers and when the clay drys it is stuck between

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24
Q

Ammonium volatilization

A

the release of ammonium into the atmosphere. nitrogen is lost as ammonia gas

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25
Q

3 factors affecting ammonium volatilization

A

pH
CEC
H2O
N mineralization

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26
Q

3 major N reactions in soil

A

mineralization
nitrification
denitrification

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27
Q

Nitrification

A

oxidation of ammonium by bacteria
Step 1: NH4+ –> NO2- gas
Step 2: NO2- –> NO3-

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28
Q

5 factors affecting nitrification

A 
pH
CEC
H2O
temperature
microorganisms
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29
Q

Denitrification

A

bacteria convert NO3- to N2 gas

sucks all the oxygen out of nitrates

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30
Q

General class of soil organisms responsible for denitrification

A

facultative anaerobic bacteria

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31
Q

5 factors affecting denitrification

A 
pH
CEC
H2O
temperature
oxygen
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32
Q

Why are soil tests for N a poor indication of fertilizer needs

A

because of the mobility of nitrates in soils and the complex transformations of nitrogen from soil organic matter

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33
Q

What leaches through soil with a high CEC faster NO3- or NH4+

A

NO3-

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34
Q

What is urease

A

soil enzyme that breaks down urea in releasing NH4+.

increases mineralization of N in urea

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35
Q

Why is ammonium nitrate a better fertilizer to apply to unirrigated turfs and pastures than urea in the summer

A

because urea tends to be lost to the air when left for extended periods of time in warm weather.
irrigation will help blend urea into soil
no special management considerations for ammonium nitrate

36
Q

When is a good time to apply urea to turfs and pastures

A

just before rain or irrigation

also works well if tilled into the soil

37
Q

Why is urea a better N source in flooded rice fields than ammonium nitrate

A

because it won’t be denitrificated

38
Q

Biological N2 fixation reaction

A

N2 + 8 H+ + 8 e− → 2 NH3 + H2

atmospheric nitrogen converted to ammonia by nitrogenase

39
Q

Nitrogenase

A

protein enzymes used to fix atmospheric nitrogen gas

40
Q

4 facts about nitrogenase

A

needs O2
needs Fe, Mo
needs living organisms (mostly rhizobrium & bradyrhizobium)
influenced by the environment (O2, temp, pH)

41
Q

4 N fixing organisms

A 
rhizobium
spirillum
cyanobacteria
clostridium
azotobacter
42
Q

Practical N managment in ag and hort soils

A 
soil pH
improve soil organic matter
don't let other nutrients get deficient
set realistic yield goals
don't over fertilize N
apply in increments
use urea in rice
use stabilized urea (urease inhibitors) in other crops
keep fields from ponding
inocculate legume seeds
43
Q

Function of S in plants

A

structural component of various enzymes
constituent of amino acids
synthesis of oils

44
Q

3 major natural sources of S in soils

A

organic matter
soil minerals
atmosphere

45
Q

Organic S in soils compromise how much of total S in root zones

A

.15-.45%

46
Q

S mineralization

A

organic S forms are transformed into inorganic

organic S –> decomposition –> SO4 2- mineralization

47
Q

S immobilization

A

opposite of mineralization
transforms inorganic S into organic S
SO4 2- –> organic S

48
Q

S fixation

A

SO4 2- –> mineral like CaSO4

49
Q

Role of P in plants

A

ATP
RNA
DNA

50
Q

In healthy plants P makes up how much of tissue dry matter

A

.2-.4%

51
Q

General deficiency symptoms of P

A 
stunted plant (short stocky)
dark or blueish green in color
52
Q

3 sources of P input

A

fertilizer
minerals
organic matter

53
Q

3 sources of P output

A

erosion
plant uptake
water runoff

54
Q

Is P a very mobile nutrient in soil systems?

A

No, its through root interception

55
Q

2 broad classifications of P in soils

A

organic

nonorganic

56
Q

Effect of mycorrhizae fungi on P uptake by plants

A

increase volume in the soil

57
Q

P eutrophication

A

a high concentration of P in a body of water causes excessive algae growth

58
Q

Main source of dissolved organic P in soils

A

animal waste

59
Q

How does the mobility of Dissolved Organic P (DOP) compare to inorganic sources of P

A

has a higher mobility

60
Q

optimum pH for P availability

A

6.5

61
Q

Fixation of P in acidic soils mostly with

A

Al, Fe, Mn

62
Q

Fixation of P in alkaline soils mostly with

A

Ca

63
Q

Compound that can remove soluble phosphates from sewage treatment water or animal wastes

A

Aluminum

64
Q

P fixation capacity of the soil

A

ability of a soil to fix P from available to unavailable

H2PO4–> CaHO4

65
Q

3 factors affect P fixation

A

pH
organic matter
clay content

66
Q

Role of K in plants

A

non-structural
water regulation through opening and closing of stomates
enzyme activation

67
Q

In healthy plants K makes up how much of tissue

A

1-4%

68
Q

Deficiency symptoms of K

A

fixing of leaf margins (usually older leaves)

69
Q

Luxury consumption

A

uptake of excessive nutrients beyond whats needed but with not adverse effects

70
Q

four states of K

A

solution
exchangeable
mineral component
fixed between sheets of some 2:1 layer silicate clays

71
Q

2 examples of popular K fertilizers

A

muriate of potash (0-0-60) KCl

sulfate of potash (0-0-50) K2SO4

72
Q

Role of Ca in plants

A

cell wall support

fruit development

73
Q

3 states of Ca in soils

A 
exchangeable Ca (available)
mineral Ca (unavailable)
complex with soil humus (unavailable)
74
Q

Relationship of Ca availability and soil % base saturation

A

B.S. goes up, Ca2+ goes up

75
Q

3 main losses of Ca (and Mg) from soils

A

leaching
crop removal
erosion

76
Q

Role of Mg in plants

A

chlorophyll

photosynthesis

77
Q

Preferred Ca/Mg range in soils

A

1:1 to 15:1

78
Q

Soil conditions where micronutrients may be deficient

A 
acidic or alkaline
organic
intensively cropped
eroded/shallow
sandy/leached
derived from some parent materials
79
Q

chelated micronutrient

A

cation micronutrient encapsulated by large organic molecules

ex: Zn-EDTA, Cu-EDTA, Fe-EDTA

80
Q

Zn role in plants

A

several, seed production and hormone constituent

81
Q

Fe role in plants

A

Redox reactions, respiration, energy, ATP production

82
Q

Cu role in plants

A

photosynthesis, protein synthesis

83
Q

Mn role in plants

A

N metabolism, assimilation

84
Q

Co role in plants

A

N fixation, vitamin B12

85
Q

B role in plants

A

cell division and growth

86
Q

Mo role in plants

A

N fixation by legumes

Soils (2 decks)

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