Soils Exam 2

Question 0

When does run off occur

Answer 0

When accumulation exceeds rare if infiltration or soil storage capacity

Question 1

Interception

Answer 1

Precipitation that never reaches soil due to vegetation

Question 2

Material that reduces evaporation and controls weeds

Answer 2

Mulch

Question 3

Eutrophication

Answer 3

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

Question 4

Oxidation if pyrite produces extreme acidity and soluble iron and sulfur

Answer 4

Acid mine drainage

Question 5

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

Answer 5

Chemical characteristics if substance

Characteristics if soil

Question 6

Provides maximum opportunity for soils to bind chemicals:

Answer 6

Matrix flow

Question 7

Greatly decreases the ability if a soil to bond chemicals

Answer 7

Macropore flow

Question 8

Preferential or bypass flow

Answer 8

Transports chemicals to groundwater more rapidly via macro pores

Question 9

Oxygen concentration does what as soil depth increases?

Answer 9

Decreases

Question 10

High saturation levels does what to o2 content?

Answer 10

Lowers it

Question 11

What are concentrations of co2 like beneath the soil surface.

Answer 11

It can be 10 to 100 times greater and be toxic

Question 12

What can anaerobic conditions in soil lead to?

Answer 12

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

Question 13

What 2 things regulate o2 availability?

Answer 13

Soil macro porosity and water content

Question 14

What two ways does soul gas exchange?

Answer 14

Mass flow and diffusion

Question 15

What is the more important form of soil gas exchange?

Answer 15

Diffusion

Question 16

What is mass flow?

Answer 16

Physical movement if air due to fluctuations in moisture content

Question 17

Why does diffusion occur?

Answer 17

Concentration gradients

Question 18

What is the partial pressure gradient?

Answer 18

A difference in every potential of gas concentration

Question 19

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

Answer 19

10

Question 20

What does water do to diffusion?

Answer 20

Slows it because it moves 10000 times slower

Question 21

Loss of electrons in a substance

Answer 21

Oxidation

Question 22

The gain of electrons

Answer 22

Reduction

Question 23

What is the electron receptor for respiration?

Answer 23

Oxygen

Question 24

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

Answer 24

Redox potential

Question 25

What happens if Eh falls below .32 volts

Answer 25

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

Question 26

Anaerobic decomposition can lead to…

Answer 26

Toxins

Question 27

What 3 factors affect soil aeration and Eh?

Answer 27

Drainage and nacroporosity

Respiration rates

Soil heterogeneity

Question 28

Is reduction good for plants?

Answer 28

No

Question 29

What kinds if soils are under frequent reducing conditions?

Answer 29

Wetland soils —> histosols

Question 30

What is a veal action process?

Answer 30

Seeds needing cold treatment to germinate

Question 31

What is biological 0?

Answer 31

5 degrees centigrade

Question 32

What happens to microbial activity as temperature rises?

Answer 32

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

Question 33

What is albedo?

Answer 33

The fraction of sunlight reflected?

Question 34

What is aspect?

Answer 34

The direction of slope of a surface