Exam 4

Question 1

pH Scale

Answer 1

0-Acidic
7-Neutral
14-Basic (Alkaline)

Question 2

Acidic Soils have more…

Answer 2

H+ ions

Question 3

OH-

Answer 3

More basic soils

Question 4

Greatest contributer to H+ ions in soil

Answer 4

Carbonic acid and other acids

Question 5

H+ recation with Aluminum

Answer 5

Creates Al3+
Absorbed at cation exchange sites.
Not exchangable, does not move and impedes cation movement

Question 6

Plants and pH

Answer 6

Plants swap cations with the soil
Realease H+ to exchange for anions in the soil

Question 7

5 unique characteristics of water

Answer 7

-Polarity: Hydrogen positive, oxygen negative
-Hydrogen bonding: Positive to negative, high boiling point, viscosity
-Hydration: Cations attract O2, H attracted to clay layers
-Adhesion/Cohesion
-Surface tension: water attracted to itself more than air

Question 8

Cation Exchange Capacity (CEC)

Answer 8

-Sum total of exchangable cations that a soil can absorb
-Higher CEC value
* More clay
* greater water holding
* more fertile soils

Question 9

Field Capacity

Answer 9

Water is held loosly in the soil, due to an excess in water

Question 10

Wilting Point

Answer 10

Water is held tightly in soil, plant cannot pull it up

Question 11

Hydraulic Conductivity

Answer 11

readiness at which liquid flows through a soil as a result of a given potential graident

Question 12

Preferential Flow

Answer 12

nonuniform downward movement of water at the surface

Question 13

Inorganic vs. organic compounds

Answer 13

-Inorganic: easier to use, less carbon chains to work through, more readily used
-Organic: most common

Question 14

NO3-

Answer 14

Nitrate

Question 15

NH4+

Answer 15

Ammonium

Question 16

Immobolization

Answer 16

Conversion of inorganic to organic

*considered an output due to organic creation

Question 17

Plant use which form of compounds

Answer 17

Inorganic
Anytime an organic form is made it is considered an imput

Question 18

Ca:Mg Ratio

Answer 18

Mg is more easily leached than Ca

Mg is at fewer exchange sites than Ca

Question 19

Name of autotrophic bacteria that fixes Ammonium to nitrite

Answer 19

Nitrosomonas

Question 20

Name of autotroph that fixes Nitrite to nitrate

Answer 20

Nitrobacter

Question 21

Five fates of Ammonium (NH4+)

Answer 21

-Immobilization
-Plant uptake
-Fixation (fixed onto the clay surface)
-Volatilization (creation of gas)
-Nitrification(NH4 to NO3)

Question 22

Inorganic Sulfur

Answer 22

-Sulfate (SO4)
-Sulfide (S 2-)

Question 23

Adsorption of Phosphorus

Answer 23

P molecules bind to surface of soil particles

Question 24

Fate of Nitrate (NO3-)

Answer 24

-Leaching: loss of nutrients because of water
Easily lost due to neg charge
-Denitrification: nitrate back into ammonium

Question 25

Ectomycorrhizae

Answer 25

non-cell penetrating plant helper fungi

Question 26

Endomycorrhizae

Answer 26

Cell penetrating plant helper fungi

Question 27

Two ways that soil organisms are important

Answer 27

Species diversity Functional diversity: utulization of different sites to fulfill a vareity of roles

Question 28

Functional redundancy

Answer 28

Ability of ecosystem to bounce back after an upset

Question 29

Saprophytic Microorganisms

Answer 29

Feed on dead tissue Large colonies of of microbial cells

Question 30

Hardest organic matter to decompose

Answer 30

Lignin: complex organic constitute, woody plant, cements cells together

Question 31

Easiest organic compound to decompose

Answer 31

Sugars, starches, and simple proteins

Question 32

Two functions of plant roots

Answer 32

-Hold plant in place -Asorb water and nutrients

Question 33

DNRA

Answer 33

Dissmilatory nitraite reduction to ammonium | -Caused by microbial process

Question 34

Fixed K (pottassium)

Answer 34

K that is fixed to the soil particle