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Soils Exam #3 > Nitrogen > Flashcards

Nitrogen Flashcards

(80 cards)

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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element that can be withdrawn from a tissue were it was originally deposited by a plant and transfered to a new tissue where it is more vitally needed at present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
can ammonificaiton happen without O2
yes just slower- like in archean period
26
Does ammonification lower pH
no it raises it. The byproduct of ammonification is one OH-/NH4+
27
do water molecules keep NH3 in solution
no- no net charge it's a water soluble gas
28
NH3 + H2O = NH4+ + OH-
ammonification
29
what will happen if you add lime to your compost
the alkaline pH will cause it to stink of ammonia
30
urea
most common N containing ingredient in mixed fertilizers in New England
31
why do manuered fields stink
it's losing its nitrogen as ammonia
32
what happens if you add ammonia NH4+ ions to soil with lots of 2:1 clays
the NH4+ ions will move into exchange sites and squeeze layers together water can't even fit between layers backwards weathering
33
how to get NH4 out of 2:1 clays
weathering
34
what type of bacteria figured out how to consume CO2 and produce O2
cyanobacteria
35
what is the aerobic nitrification equation
NH4+ + 2O2 --> NO3- + 2H+ + H2O
36
what does aerobic nitrogen transformation produce
energy that is captured by chemoautotrophic bacteria for growth
37
Does nitrification require Nitrification post photoautotrophic bacteria producitng O2?
yes- oxygen killed most others
38
post photo autotrophic bacteria- does nitrificaiton increase pH
no it lowers it
39
what do nitrifiers do
break down NH4+ to NO3-
40
why are nitrifiers good for plants
EXCHANGABLE nitrogen at these sites
41
what is the overall reaction of nitrification
NH4+ + 2O2 -----> NO3- + 2H+ + H2O
42
what captures the energy of oxidation and nitrification
chemoautotrophic bacteria
43
Does nitrification require O2
YES!!
44
what affect does nitrification have on pH
lowers pH creates acidity (2H+)
45
which is toxic to your crops and animals : nitrite or nitrate
nitrite
46
can complete nitrification be done by a chemoautotrophic microbe
no- must be divided by 2 chemoautotrophic nitrifiers
47
what two chemoautotrophic nitrifiers nitrify
ammonium oxidizers and nitrite oxidizers
48
what bugs create all the acidity during nitrification
ammonium oxidizers
49
what bugs create no acidity when nitrification
nitrite oxidizers
50
what are the conditions for nitrification
warm, well aerated, not too dry
51
do nitrifiers like the cold
no
52
what should you do for early spring crops
give them some nitrate
53
do nitrifiers like acidity
no
54
NH4+ oxidizers will keep working up to a pH of 9. what has caused this resilliency
they go into sites where ammonification is happening ammonification releases NH4+ and OH-
55
in temperate regions- do nitrate or nitrite leach through soils of temperate regions easilt
both
56
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
T- roots and microbes must stay neutral because otherwise it would repel needed nutrient ions of the same charges
57
To avoid developing an overall charge, what do plants do
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
does nitrate assimilation cause pH to increase
yes because oH is being kicked out and H+ is taken in
59
For the assimilation of ammonium (NH4+) what happens in plant root
OH- comes in or H+ leaves to keep charge samw
60
rhizosphere
all soil close enough to the root to be affected by the root abt 5mm from root
61
TF rhizosphere is more affected by what form of Nitrogen the plant is assimilating
T
62
TF during the day the rhizosphere is moister than at night
F its drier
63
which is the oxidation of nitrogen NH4+ -> NO3- NO3- -> NH4+
NO3- -> NH4+ increasing charge
64
if O2 gets consumed by aerobic respiration what do the microbes do
suffocate and die pack DNA into spores and die ferment find alternative oxidizer
65
denitrification
turning the N in nitrate into N2 gas
66
what happens to energy o2 and pH with denitrification
energy- provides energy O2- anerobic provess pH- raise pH
67
denitrification equation
NO3- -> NO2- -> [NO] -> N2O -> N2
68
in soil aggregates, where is nitrification likely to happen - outside or inside
outside where it's moist, denitrification on the inside
69
at 90% filled with water pore space is nitrification going to have a high or low rate
low it will be denitrification
70
nitrogen fixation
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
do eukaryotes do biological nitrogen fixation
no only prokaryotes
72
biological nitrogen fixation energy o2 and ph
energy- high requirement of energy O2- bacteria will protect the enzymes from O2. Occurs aerobically and anaerobically pH- no effect
73
heterotopic bacteria who can fix N have advantage over those unable to fix N
T when carbon is abundant and N is in short supply
74
if there is ammonium or nitrate in a soil, what will nitrogen fixing bacteria do
stop
75
why do plants that excrete sugars to get a N fixators attention not work
bacteria gets to the sugars first anf also steal the ammonium as well
76
plants will form nodules around N fixators and never bacteria
hopefully true but not never
77
heghemoglobin
obygen transporting compound like hemoglobin
78
how are leghemoglobin used to trap rnodules
it delivers O2 to vell without allowing free o2 to diffuse int o the cell and clobber the O2- sensitive N-fixing enzymes
79
why should you fertilize your legumes with rhizobia instead of N
N is already avail to them its free in solution
80

Soils Exam #3 (6 decks)

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