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Soils Test 3 Flashcards

(86 cards)

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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
3 factors affecting ammonium volatilization
pH CEC H2O N mineralization
26
3 major N reactions in soil
mineralization nitrification denitrification
27
Nitrification
oxidation of ammonium by bacteria Step 1: NH4+ --> NO2- gas Step 2: NO2- --> NO3-
28
5 factors affecting nitrification
``` pH CEC H2O temperature microorganisms ```
29
Denitrification
bacteria convert NO3- to N2 gas | sucks all the oxygen out of nitrates
30
General class of soil organisms responsible for denitrification
facultative anaerobic bacteria
31
5 factors affecting denitrification
``` pH CEC H2O temperature oxygen ```
32
Why are soil tests for N a poor indication of fertilizer needs
because of the mobility of nitrates in soils and the complex transformations of nitrogen from soil organic matter
33
What leaches through soil with a high CEC faster NO3- or NH4+
NO3-
34
What is urease
soil enzyme that breaks down urea in releasing NH4+. | increases mineralization of N in urea
35
Why is ammonium nitrate a better fertilizer to apply to unirrigated turfs and pastures than urea in the summer
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
When is a good time to apply urea to turfs and pastures
just before rain or irrigation | also works well if tilled into the soil
37
Why is urea a better N source in flooded rice fields than ammonium nitrate
because it won't be denitrificated
38
Biological N2 fixation reaction
N2 + 8 H+ + 8 eāˆ’ ā†’ 2 NH3 + H2 | atmospheric nitrogen converted to ammonia by nitrogenase
39
Nitrogenase
protein enzymes used to fix atmospheric nitrogen gas
40
4 facts about nitrogenase
needs O2 needs Fe, Mo needs living organisms (mostly rhizobrium & bradyrhizobium) influenced by the environment (O2, temp, pH)
41
4 N fixing organisms
``` rhizobium spirillum cyanobacteria clostridium azotobacter ```
42
Practical N managment in ag and hort soils
``` 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
Function of S in plants
structural component of various enzymes constituent of amino acids synthesis of oils
44
3 major natural sources of S in soils
organic matter soil minerals atmosphere
45
Organic S in soils compromise how much of total S in root zones
.15-.45%
46
S mineralization
organic S forms are transformed into inorganic | organic S --> decomposition --> SO4 2- mineralization
47
S immobilization
opposite of mineralization transforms inorganic S into organic S SO4 2- --> organic S
48
S fixation
SO4 2- --> mineral like CaSO4
49
Role of P in plants
ATP RNA DNA
50
In healthy plants P makes up how much of tissue dry matter
.2-.4%
51
General deficiency symptoms of P
``` stunted plant (short stocky) dark or blueish green in color ```
52
3 sources of P input
fertilizer minerals organic matter
53
3 sources of P output
erosion plant uptake water runoff
54
Is P a very mobile nutrient in soil systems?
No, its through root interception
55
2 broad classifications of P in soils
organic | nonorganic
56
Effect of mycorrhizae fungi on P uptake by plants
increase volume in the soil
57
P eutrophication
a high concentration of P in a body of water causes excessive algae growth
58
Main source of dissolved organic P in soils
animal waste
59
How does the mobility of Dissolved Organic P (DOP) compare to inorganic sources of P
has a higher mobility
60
optimum pH for P availability
6.5
61
Fixation of P in acidic soils mostly with
Al, Fe, Mn
62
Fixation of P in alkaline soils mostly with
Ca
63
Compound that can remove soluble phosphates from sewage treatment water or animal wastes
Aluminum
64
P fixation capacity of the soil
ability of a soil to fix P from available to unavailable | H2PO4--> CaHO4
65
3 factors affect P fixation
pH organic matter clay content
66
Role of K in plants
non-structural water regulation through opening and closing of stomates enzyme activation
67
In healthy plants K makes up how much of tissue
1-4%
68
Deficiency symptoms of K
fixing of leaf margins (usually older leaves)
69
Luxury consumption
uptake of excessive nutrients beyond whats needed but with not adverse effects
70
four states of K
solution exchangeable mineral component fixed between sheets of some 2:1 layer silicate clays
71
2 examples of popular K fertilizers
muriate of potash (0-0-60) KCl | sulfate of potash (0-0-50) K2SO4
72
Role of Ca in plants
cell wall support | fruit development
73
3 states of Ca in soils
``` exchangeable Ca (available) mineral Ca (unavailable) complex with soil humus (unavailable) ```
74
Relationship of Ca availability and soil % base saturation
B.S. goes up, Ca2+ goes up
75
3 main losses of Ca (and Mg) from soils
leaching crop removal erosion
76
Role of Mg in plants
chlorophyll | photosynthesis
77
Preferred Ca/Mg range in soils
1:1 to 15:1
78
Soil conditions where micronutrients may be deficient
``` acidic or alkaline organic intensively cropped eroded/shallow sandy/leached derived from some parent materials ```
79
chelated micronutrient
cation micronutrient encapsulated by large organic molecules | ex: Zn-EDTA, Cu-EDTA, Fe-EDTA
80
Zn role in plants
several, seed production and hormone constituent
81
Fe role in plants
Redox reactions, respiration, energy, ATP production
82
Cu role in plants
photosynthesis, protein synthesis
83
Mn role in plants
N metabolism, assimilation
84
Co role in plants
N fixation, vitamin B12
85
B role in plants
cell division and growth
86
Mo role in plants
N fixation by legumes

Soils (2 decks)

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