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Soils Exam #3 > Nitrogen > Flashcards

Nitrogen Flashcards

1
Q

what do plants want from their soil

A

O2
watwe
Strength
Buffer pH
nutrients

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2
Q

6 Macronutrients

A

N P K Ca Mg S

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3
Q

Nitrogen use

A

protiens chlorophyll DNA RNA

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4
Q

Phosphorous use

A

DNA RNA ATP

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5
Q

Potassium use

A

Osmosis- open and close stomata

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6
Q

Ca use

A

crosslink carboxylate groups

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7
Q

Mg use

A

chlorophyll

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8
Q

sulfur use

A

amino acids- cysteine and methionine

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9
Q

Mobile nutrient

A

element that can be withdrawn from a tissue were it was originally deposited by a plant and transfered to a new tissue where it is more vitally needed at present

Transferring an element from an old leaf to a new leaf

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10
Q

immobile nutrients

A

x moved after deposition

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11
Q

N P K immobile or monile

A

mobile

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12
Q

what color do leaves with insufficient nitrogen turn

A

yellow

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13
Q

will yellowing leaves occur on the newest, or oldest growth

A

oldest - N is mobile

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14
Q

what are the two most important forms of N in soil

A

ammonium- NH4
Nitrate- NO3

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15
Q

ammonium in soil where is it stored

A

since it’s a cation, soil can store it on it’s exchange sites

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16
Q

what flushes ammonium off of exchange sites and therefore available to plants

A

rain

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17
Q

how do most crops obtain the N in their diets

A

NO3-

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18
Q

do clays attract NO3-

A

no

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19
Q

where can plants find NO3-

A

in solution

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20
Q

does rain flush out NO3-

A

yes

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21
Q

does the ancient N cycle of the N conversion to NH4+ still exist to raise pH

A

yes in conifer forests on sandy soils

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22
Q

since bacteria hate acid, what does the mineralization of organic N into NH4+ in the sandy coniferous low pH forests

A

fungi

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23
Q

ammonification

A

turning OM into ammonium

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24
Q

do microbes need energy to perform ammonification

A

not extra, they already to ammonification when they mineralize the organic carbon they took up in things like oligopeptised

They get energy from the oxidation of carbon

they end up with an excess of Nitrogen

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25
Q

can ammonificaiton happen without O2

A

yes just slower- like in archean period

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26
Q

Does ammonification lower pH

A

no it raises it. The byproduct of ammonification is one OH-/NH4+

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27
Q

do water molecules keep NH3 in solution

A

no- no net charge

it’s a water soluble gas

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28
Q

NH3 + H2O = NH4+ + OH-

A

ammonification

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29
Q

what will happen if you add lime to your compost

A

the alkaline pH will cause it to stink of ammonia

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30
Q

urea

A

most common N containing ingredient in mixed fertilizers in New England

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31
Q

why do manuered fields stink

A

it’s losing its nitrogen as ammonia

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32
Q

what happens if you add ammonia NH4+ ions to soil with lots of 2:1 clays

A

the NH4+ ions will move into exchange sites and squeeze layers together

water can’t even fit between layers

backwards weathering

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33
Q

how to get NH4 out of 2:1 clays

A

weathering

34
Q

what type of bacteria figured out how to consume CO2 and produce O2

A

cyanobacteria

35
Q

what is the aerobic nitrification equation

A

NH4+ + 2O2 –> NO3- + 2H+ + H2O

36
Q

what does aerobic nitrogen transformation produce

A

energy that is captured by chemoautotrophic bacteria for growth

37
Q

Does nitrification require Nitrification post photoautotrophic bacteria producitng O2?

A

yes- oxygen killed most others

38
Q

post photo autotrophic bacteria- does nitrificaiton increase pH

A

no it lowers it

39
Q

what do nitrifiers do

A

break down NH4+ to NO3-

40
Q

why are nitrifiers good for plants

A

EXCHANGABLE nitrogen at these sites

41
Q

what is the overall reaction of nitrification

A

NH4+ + 2O2 —–> NO3- + 2H+ + H2O

42
Q

what captures the energy of oxidation and nitrification

A

chemoautotrophic bacteria

43
Q

Does nitrification require O2

A

YES!!

44
Q

what affect does nitrification have on pH

A

lowers pH creates acidity (2H+)

45
Q

which is toxic to your crops and animals : nitrite or nitrate

A

nitrite

46
Q

can complete nitrification be done by a chemoautotrophic microbe

A

no- must be divided by 2 chemoautotrophic nitrifiers

47
Q

what two chemoautotrophic nitrifiers nitrify

A

ammonium oxidizers and nitrite oxidizers

48
Q

what bugs create all the acidity during nitrification

A

ammonium oxidizers

49
Q

what bugs create no acidity when nitrification

A

nitrite oxidizers

50
Q

what are the conditions for nitrification

A

warm, well aerated, not too dry

51
Q

do nitrifiers like the cold

A

no

52
Q

what should you do for early spring crops

A

give them some nitrate

53
Q

do nitrifiers like acidity

A

no

54
Q

NH4+ oxidizers will keep working up to a pH of 9. what has caused this resilliency

A

they go into sites where ammonification is happening

ammonification releases NH4+ and OH-

55
Q

in temperate regions- do nitrate or nitrite leach through soils of temperate regions easilt

A

both

56
Q

TF it matters if the plant is going to take up nitrogen by ammonium or nitrate when looking at the effect on pH N assimilation will be

A

T- roots and microbes must stay neutral because otherwise it would repel needed nutrient ions of the same charges

57
Q

To avoid developing an overall charge, what do plants do

A

They either take in an H+ ion for every NO3-(nitrate) they take in
or kick out an OH- for every NO3- they take in

58
Q

does nitrate assimilation cause pH to increase

A

yes because oH is being kicked out and H+ is taken in

59
Q

For the assimilation of ammonium (NH4+) what happens in plant root

A

OH- comes in or H+ leaves to keep charge samw

60
Q

rhizosphere

A

all soil close enough to the root to be affected by the root

abt 5mm from root

61
Q

TF rhizosphere is more affected by what form of Nitrogen the plant is assimilating

A

T

62
Q

TF during the day the rhizosphere is moister than at night

A

F its drier

63
Q

which is the oxidation of nitrogen

NH4+ -> NO3-
NO3- -> NH4+

A

NO3- -> NH4+

increasing charge

64
Q

if O2 gets consumed by aerobic respiration what do the microbes do

A

suffocate and die
pack DNA into spores and die
ferment
find alternative oxidizer

65
Q

denitrification

A

turning the N in nitrate into N2 gas

66
Q

what happens to energy o2 and pH with denitrification

A

energy- provides energy

O2- anerobic provess

pH- raise pH

67
Q

denitrification equation

A

NO3- -> NO2- -> [NO] -> N2O -> N2

68
Q

in soil aggregates, where is nitrification likely to happen - outside or inside

A

outside where it’s moist, denitrification on the inside

69
Q

at 90% filled with water pore space is nitrification going to have a high or low rate

A

low

it will be denitrification

70
Q

nitrogen fixation

A

conversion of nitrogen from botanically useless N2 into ammonia NH3

ammonia gets converset to organic N in plant

plants and bugs move slower than a molecule of N2 in the air

N is fixed

71
Q

do eukaryotes do biological nitrogen fixation

A

no only prokaryotes

72
Q

biological nitrogen fixation energy o2 and ph

A

energy- high requirement of energy

O2- bacteria will protect the enzymes from O2. Occurs aerobically and anaerobically

pH- no effect

73
Q

heterotopic bacteria who can fix N have advantage over those unable to fix N

A

T when carbon is abundant and N is in short supply

74
Q

if there is ammonium or nitrate in a soil, what will nitrogen fixing bacteria do

A

stop

75
Q

why do plants that excrete sugars to get a N fixators attention not work

A

bacteria gets to the sugars first anf also steal the ammonium as well

76
Q

plants will form nodules around N fixators and never bacteria

A

hopefully true but not never

77
Q

heghemoglobin

A

obygen transporting compound like hemoglobin

78
Q

how are leghemoglobin used to trap rnodules

A

it delivers O2 to vell without allowing free o2 to diffuse int o the cell and clobber the O2- sensitive N-fixing enzymes

79
Q

why should you fertilize your legumes with rhizobia instead of N

A

N is already avail to them its free in solution

80
Q
A

Soils Exam #3 (6 decks)

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