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Flashcards in Soils exam 1 Deck (64):
0

Oxidation if pyrite produces extreme acidity and soluble iron and sulfur

Acid mine drainage

1

Is reduction good for plants?

No

2

What happens if Eh falls below .32 volts

A soil is devoid of o2 and other elements are used for microbial metabolism

3

The ability if soils to bind chemical substances depends on these 3 things:

Chemical characteristics if substance
Characteristics if soil

4

Oxygen concentration does what as soil depth increases?

Decreases

5

Preferential or bypass flow

Transports chemicals to groundwater more rapidly via macro pores

6

What is mass flow?

Physical movement if air due to fluctuations in moisture content

7

What is biological 0?

5 degrees centigrade

8

What 3 factors affect soil aeration and Eh?

Drainage and nacroporosity

Respiration rates

Soil heterogeneity

9

What happens to microbial activity as temperature rises?

It doubles for every 10 degrees and dies around 50 or 60

10

What can anaerobic conditions in soil lead to?

Production of reduced nitrogen gases, methane gases, hydrogen sulfide, ethylene

11

What does water do to diffusion?

Slows it because it moves 10000 times slower

12

What is aspect?

The direction of slope of a surface

13

Loss of electrons in a substance

Oxidation

14

What is albedo?

The fraction of sunlight reflected?

15

Anaerobic decomposition can lead to...

Toxins

16

What is the electron receptor for respiration?

Oxygen

17

What is a veal action process?

Seeds needing cold treatment to germinate

18

The measure in volts of how aerobic or anaerobic a system is. A measure of electrical potential of a substance to give up electrons

Redox potential

19

What is the more important form of soil gas exchange?

Diffusion

20

When does run off occur

When accumulation exceeds rare if infiltration or soil storage capacity

21

What is the partial pressure gradient?

A difference in every potential of gas concentration

22

Provides maximum opportunity for soils to bind chemicals:

Matrix flow

23

Why does diffusion occur?

Concentration gradients

24

What 2 things regulate o2 availability?

Soil macro porosity and water content

25

Greatly decreases the ability if a soil to bond chemicals

Macropore flow

26

High saturation levels does what to o2 content?

Lowers it

27

What kinds if soils are under frequent reducing conditions?

Wetland soils ---> histosols

28

What two ways does soul gas exchange?

Mass flow and diffusion

29

What are concentrations of co2 like beneath the soil surface.

It can be 10 to 100 times greater and be toxic

30

At what percentage air porosity dies microbial and root respiration cease?

10

31

Eutrophication

Excess nutrients (phosphorus) that leads to excessive aquatic growth and ultimately oxygen depletion

32

Material that reduces evaporation and controls weeds

Mulch

33

Interception

Precipitation that never reaches soil due to vegetation

34

The gain of electrons

Reduction

35

1:1 type composed of which sheets

1 tetrahedra, 1 octahedral

36

Tetrahedral sheet is composed of:

4 oxygen
1 silicon at center

37

1:1 clay type example

Kaolinite

38

2:1 clay groups without shrinking and swelling:

Fine grained micas(ilites) and chlorites

39

Examples of 2:1 clays

Smectites

40

Octahedral sheet is made of which atoms

6 oxygen/hydroxyl
With an aluminum/magnesium at center

41

Eutrophication

Excess nutrients (phosphorus) in fresh water leading to excessive aquatic growth and ultimately oxygen depletion

42

2:1 type made if which sheets

2 tetrahedra, 1 octahedral

43

2:1 type shrinking and swelling clay groups

Smectites
Vermiculites

44

Important silicate clays

Phyllo silicates

45

Difference between anions and cations

Anions are negative cations are positive

46

What happens when a soil accepts H

It lowers the soils ph

47

What is CEC?

The amount of cations a soil can contain

48

If you increase CEC, what happens to plants ability to store nutrients?

Increases

49

What 3 factors raise CEC?

Amount of clay
Amount if organic matter
Increase in soil ph

50

How do soils acidify?

Respiration in roots and microbes creating co2 that reacts with water to create weak acids

51

What is a very toxic element to plants?

Al3+

52

What are the 3 pools of soil acidity?

Active acidity
Exchangeable acidity
Residual acidity

53

What determines active acidity?

Ph

54

What determines exchangeable acidity?

Cation exchange?

55

What determines residual acidity?

Ph buffered extractent

56

When do herbicides become soluble?

At high ph

57

When do metals become soluble?

At low ph

58

When little or no mg is in a carbonate it is

Calcitic

59

When a carbonate has increasing amounts if mg it becomes

Dolomitic

60

On what 4 things does a lining requirement depend?

Change in ph required
Buffering capacity
Type of lime used
The fineness of lime

61

What is cce?

The neutralizing value of lining material

62

How is salinity measured?

Electrical conductivity

63

How is sod ivory measured?

Exchangeable sodium percentage