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Soils > Exam 4 > Flashcards

Exam 4 Flashcards

0
Q

Acid in terms of chemistry

A

A substance which gives off h+ ions, and is a solid

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1
Q

Under what climatic condition are you likely to have more soil acidification?

A

High rainfall areas

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2
Q

What does ph indicate?

A

The degree of acidity or alkalinity of the soil.

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3
Q

What does ph measure in terms of chemistry?

A

The quantity of H+ ions

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4
Q

What is the precise difference in H ion concentration between a soil with a ph of 4 and one with a ph of 6

A

4=10 to the 4th
6=10 to the 6th
Equals 100x difference

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5
Q

How is an acid soil neutralized?

A

A base must be added

Acid+ Base = water + salt

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6
Q

Name the 3 major causes for the development of soil acidity

A

Al compounds
Loss of basic cations (by leaching)
Plant removal

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7
Q

Natural sources of acids

Non-natural sources of acids

A 
Natural
Acid rain
OM
Clays
Oxidation of n & sulfur compounds
Release of AL from exchange sites and oxides
Non-natural
Fertilizers
Acid rain
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8
Q

Discuss the connection between the release of al compounds and ph in the soil?

A

There is more H+ to be released

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9
Q

Fertilizers that increase soil acidity?

A

Nitrogen and sulfur containing fertilizers

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10
Q

What is the target range for most plants?

A

6.2-6.8

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11
Q

Wh might a low ph be bad for plants?

A

Changes the form of nutrients which makes them unavailable to plants

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12
Q

Effects of acid soils.
Microorganisms
Macronutrients
Micronutrient

A

Microorganisms-are inhibited
Macronutrience- are all reduced in availability
Micronutrients-malibdumum & boron have low availability. Copper cobalt manganese iron zinc become extra available= toxic

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13
Q

What are other effects of increased al solubility in acid soils?

A

Interferes with plant development harms microbes

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14
Q

What is lime?

A

Compound that neutralizes soil acidity

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15
Q

2 ways lime reduces acidity?

A

Release oh negative which binds with h+

Calcium pushes h+ off cec

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16
Q

Effects of over liming

A

Soil structure collapse

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17
Q

5 liming materials

A 
Calcium carbonate 
Calcium oxide Best
Calcium hydroxide
Dolomite
Slag 
Marl 
Ash
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18
Q

Effects neutralization of lime

A

Purity

Fineness

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19
Q

Indicators of liming needs

A

Ph

Base saturation

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20
Q

Selection of liming material

A 
Cost
Effectiveness
Nutritional value
Other nitriances
Ease of using
Water content low
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21
Q

Reduce effectiveness of low ph

A

Not altering the ph
Gypsum
-reduce al
Add nutrient

22
Q

Soil characteristics effecting om

A 
Cec
Whc
Soil aggregation
Nutrient supply
Microbes habitat
23
Q

What is dry matter composed of?

A

90-95% c h and o

5-10 comes from soil

24
Q

Organic compounds in soil

A

Carbohydrates*

25
Q

Decomp of om

A

1 enzyme oxidation
2 nutrients are releases
3 biomass is resistant to future degradation

26
Q

Effects of low air and cold o2

A

Will slow decomp

27
Q

4 aspects of organic residue quality

A

Composition
Location
Particle size
C/N rationp

28
Q

C and N connected in residue

A

Microbes consume carbon but need n to do so

29
Q

C/N ratio groups

A

10/1 humus
20-30/1sufficient n in s for decomp
30/1+ n from soil is required for decomp

30
Q

Decomp process

A 
Om added to soil
Micobes eat
Nitrate in soil drops
Co2 rises
C/N r drops
Om is consumed microbes die co2 drops nitrate released 
4-8 weeks
31
Q

Comprises om

A

Everything living + formerly living

32
Q

Humus

A

Compounds created from organic compounds created by microbes

33
Q

Benifits of om in soil

A 
Release of nutrients
Cec increase
Better soil structure
Buffer ph change
(if on soil reduce erosion)
34
Q

Why om bad?

A

Allelopathy

35
Q

Global carbon cycle needs

A

330 kg ha yr

36
Q

Effect c in soil

A

Vegetation type
Climate
Texture
Cultivation

37
Q

What form of n so plants prefer

What is second best?

A

Nitrate

No3- no2-

38
Q

Ultimate source of n

A

Atmosphere

39
Q

4 sources of n

A

Biological fixation
Climatic
Natural fertilizers
Synthetic fertilizers

40
Q

N conversion of biological fixation?

A

N2-NO3

41
Q

How much does nit fix provide?

A

50-80%

rest from soil

42
Q

Free living n fixing organisms

A

Blue-green algae
Azospirullium
Azotobactor

43
Q

Symbiotic n fixing organization

A

Bacteria living in plant roots (legumes only)

44
Q

% of n from inorganic form?

A

2-5% of total n

45
Q

Mineralization?

Immobilization?

A

Mineralization - nitrate or no4+

immobilization - organic *** bad

46
Q

Process of nitrification

A

NH3-NO2- -NO3-

Microbe cause reaction through activity

47
Q

Process of denitrification

A

NO3- -NO2-NO-N2O-N2 bad

Microorganisms cause reaction

48
Q

6 forms of n are connected

A 
NH3
NO2
NO3
NO
N2O
N2
49
Q

What causes change in forms of n to occur?

A

Microbes activity

50
Q

Use of sulfur in plants

A

Enzyme and vitamin production

Part of photosynthesis

51
Q

How sulfur enter plant? What chemical form?

A

SO2 leaves

SO4- roots

52
Q

6 pools of sulfur

A 
Organic compounds
Primary minerals
Elemental sulfur
Clay compounds
Soil solution as so4-
Atmospheric

Soils (4 decks)

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