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Soils > Nitrogen Economy > Flashcards

Nitrogen Economy Flashcards

1
Q

is an essential primary macronutrient that commonly limits plant growth

A

N

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2
Q

is a component of proteins and nucleic acids. It is also an integral part of chlorophyll and a component of ADP and ATP.

A

N

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3
Q

T or f

Deficiency of N causes chlorosis, stunted growth, low protein content, and the plant matures early.

A

T

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4
Q

Deficiency of N leads to excessive vegetative growth, lodging, and reduced yield quality.

T or f?

A

F - OVERSUPPLY of N leads to excessive vegetative growth, lodging, and reduced yield quality

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5
Q

Atmosphere contains__% N2, 21% O2, and 0.04% CO2 gas

A

78% of N2

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6
Q

Healthy plants contain__-__% N

A

2.0-4.0%

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7
Q

N Deficiency observed on
“older leaves” or “newer leaves”?

A

Older leaves

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8
Q

“Plants are more susceptible to disease & insect pests”

N oversupply or N deficiency

A

N oversupply

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9
Q

Form of nitrogen in the atmosphere, this form of nitrogen must be transformed to usable forms before it is available for plant uptake

A

Nitrogen gas (N2)

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10
Q

Can escape from the surface of the soil under certain conditions and is harmful to plants in high quantities.

*Basic building block of commercial nitrogen fertilizers

A

Ammonia gas (NH3)

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11
Q

Soil particles attract and retain ammonium on cation exchange complexes.

This form may be directly taken up by plants

A

Ammonium (NH4+)

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12
Q

Second form of nitrogen which is available for plant uptake.

Highly mobile.

In highly weathered soil, it is stored in anion exchange capacity and become less mobile

A

Nitrate NO3+

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13
Q

Intermediate product in the conversion of ammonium to nitrate (nitrification). Present in low quantities, but is toxic to plants

A

Nitrite NO2-

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14
Q

Must be converted to ammonium before it is used by plants. This conversion occurs with time and is know as mineralization

A

Organic nitrogen

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15
Q

N in soil may come from residues, fertilizers, manures, precipitation

T or f?

A

T

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16
Q

__________can reduce efficiency of unprotected nitrogen fertilizer applications.

A

Natural loss mechanisms

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17
Q

A bio geochemical process through which N is converted into many forms

A

N cycle

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18
Q

__-__% of soil N exists in organic form (protein, amino acids)

A

95-99%

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19
Q

95-99% of soil N exists in ___ form

A

Organic form

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20
Q

Conversion of organic nitrogen to inorganic (NH4-N) by microbes

A

Mineralization

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21
Q

Two step process whereby organic matter is broken down by soil microorganisms into ammonium

A

Mineralization

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22
Q

is the decomposition of proteins and the release of amines or amine groups (R-NH2), urea and amino acids (lysine-CH2NH2COOH; alanine-CH3CHNH2COOH).

A

1st process: Aminization

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23
Q

Aminization process is carried out by the ff. Except:

Pseudomonas
Bacilli
Clostridium
Aerobacter
Serrotia
Micrococcus

A

Aerobacter

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24
Q

Amines, urea and amino acids produced during aminization of organic N are decomposed by other heterotrophs with
release of NH 4 +

A

2nd process: Ammonification-

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25
Q

The ff are under ammonification. TRUE OR FALSE?

Bacillus, Micrococcus, Sarcina, Aerobacter

A

True

26
Q

1+1=?

A

Magellan

27
Q

The ff. Are Fate of ammonium in soil. EXCEPT

  1. Plant uptake/absorption through roots
  2. Nitrification
  3. Microbial immobilization
  4. Ion exchange & fixation in clay lattice 5. Organic matter complexation
  5. Volatilization
    7.Leaching
A
  1. Leaching
28
Q

Conversion of inorganic N (NO3 - & NH4 +) into organic forms

• Both biological and nonbiological (abiotic)process

A

Immobilization

29
Q

____takes place when organic residues are
poor in N

A

Immobilization

30
Q

T or f

Mobilized nutrients are not readily lost from the soil by leaching, volatilization and denitrification

A

F - IMMOBILIZED NUTRIENT

31
Q

Diploma or diskarte

A

Matug

32
Q

Addition of organic material with high C : N ratio results in depletion of soil nitrate. The activity of the decomposers is greatly stimulated and they use whatever nitrogen is present.

T or f

A

T

33
Q

• C/N ratio <20

Mineralization or immobilization?

A

Mineralization

34
Q

C/N >30 🡪

Mineralization or immobilization?

A

immobilization

35
Q

enough N to satisfy the needs of decomposers & enough N for plant use.

A. C/N ratio <20
B. C/N >30
C. C/N 20-30

A

C/N 20-30

36
Q

Average C/N ratio of bacteria and fungi is?

A

8:1

37
Q

• Oxidation of ammonium to nitrate

• Carried out by autotrophs

A

Nitrification

38
Q
  1. Good supply of NH4 + ions
  2. Carbon sources (bicarbonates & CO2)
  3. Population of nitrifying organisms
  4. Soil pH (8.5 optimum)
  5. Aerobic condition
  6. Moisture content @ field capacity (60% water-filled pores)
  7. Soil temperature (20-300C )

The following are factors affecting _____?

A

Nitrification

39
Q

Biological reduction of nitrate (NO3-) and nitrite (NO2 -) to dinitrogen (N2) gas and nitrous oxide (N20).

A

Denitrification

40
Q

The process is mostly carried out by FACULTATIVE ANAEROBIC BACTERIA (heterotrophs) such as Pseudomonas, Bacillus, Thiobacillus, Alcaligenes, Micrococcus and Achromobacteria

A

Denitrification

41
Q

It is detrimental to agriculture because nitrogen is lost from soil

A

Denitrification

42
Q

Warm temperature (250 C-350C optimum temp.) can affect denitrification

T or f

A

T

43
Q

N loss in rice fields through:

-Volatilization:__-__%
-Denitrification:__-__%

A

Volatilization: 10-60%

Denitrification: 5-10%

44
Q

When urea is BROADCASTED without immediate incorporation, N losses of up to 50% and more can be expected.

T or f

A

T

45
Q

a pH greater than 7.5 allows for considerable loss of NH3 due to NITRIFICATION

T or f?

A

False- VOLATILIZATION

46
Q

urea have greater loss than ammonium fertilizer.

T or f

A

T

47
Q

The ff are Factors affecting volatilization. EXCEPT

Soil pH

Type of fertilizer

Method of fertilizer placement

Soil temperature

Soil moisture

Buffering capacity

None of the above

A

None of the above

Sila tanan factors hihi

48
Q

____ promotes volatilization. Thus, volatilization is greatest as the soil dries after reaching field capacity

A

Evaporation

49
Q

Waiting at least __ month after lime materials had been applied.

A

1 month

50
Q

In the case of ___, irrigation immediately after application.

Ammophos
Urea
Solophos

A

Urea

51
Q

NH4+ fixation by clay minerals is generally greater in subsoil than in topsoil

T or f

A

T

52
Q

In highly weathered soils, NH 4 + fixation is major.

T or f

A

F= In highly weathered soils, NH + fixation is MINOR

53
Q

Ammonium fixation by 2:1 expanding clay

A

smectite, mica and vermiculite

54
Q

the loss of nitrate N as water drains through the soil profile, moving out of the range of plant rooting systems

A

Leaching

55
Q

Common on soils with low water holding capacity
✔ Sands and loamy sandy
✔ can occur in silt loam soils

A

Leaching

56
Q

NITRITE is leachable form.

T OR F

A

F- NITRATE

57
Q

These are natural fertilizers in which is bound to organic molecule such as animal manure, decaying plant residues, industrial wastes and many others.

A

Organic sources

58
Q

occurs at 400-5000C
and 200-1,000 atmospheres

A

Synthetic ammonia process-

59
Q

requires about 1,1000 degree C and highly purified N gas is reacted with calcium carbide to form calcium cyanamide.

CaC2 + N2——–CaCN2 + C

A

Cyanamide process

60
Q

21-0-0

What fertilizer?

A

Ammonium sulfate

61
Q

Identify Chemical reactions of ammonium sulfate whether upland or lowland

(NH4 ) SO4 ——–2NH4+ + SO4 2-

A

Lowland

62
Q

(CO(NH2)2

What fert

A

Urea

Soils (4 decks)

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