Agrn Test 2

Front 1

For a structural engineer, which type of clay would provide the most troublesome site on which to build home/road?

Back 1

Smectite

Front 2

The structures of 2:1 clay minerals are so-named because they contain _______________.

Back 2

two tetrahedral layers for every octahedral layer

Front 3

Isomorphous substitution creates net negative charges in clay micelles. A typical example of this process is the substitution of __________.

Back 3

Mg2+ for Al3+ in an octahedral

Front 4

What would be the net charge of a neutral soil colloid if Si+4 is replaced by Al+3 in the tetrahedral sheet?

Back 4

negative

Front 5

Which of the following soil is expected to have the highest acidic cations as the percentage of CEC?

Back 5

ultisols at pH 4.4

Front 6

________ is expected to be dominant in the warm and humid soils of Alabama compared to arid Nevada.

Back 6

kaolinite

Front 7

_______________ is the sum total of exchangeable cations that a soil can adsorb.

Back 7

Cation exchange capacity (CEC)

Front 8

In general, the CEC of ________________ is more significantly affected by soil pH.

Back 8

Al-oxides
Fe-oxides
humus

Front 9

Relatively speaking, as weathering intensity increases, the CEC of a soil will _____________.

Back 9

decrease

Front 10

The colloidal fraction of the soil is the seat of soil cations and anions where soil physical and chemical reactions take place.

Back 10

True

Front 11

The cation exchange capacity of a soil is affected by:

Back 11

type of soil colloids
amount of soil colloids
soil pH

Front 12

Which of the following cations are closely associated with soil acidity?
a. Ca+2 and Mg+2
b. K+1 and Na+1
c. OH-1 and CO3
-2

Back 12

none of the above

Front 13

As soil pH increases, the acid saturation of the soil colloid will:

Back 13

decrease

Front 14

A soil at pH 3.5 has _______________ H+ concentration compared to a soil at pH 5.5.

Back 14

100X more

Front 15

Soil acidity is defined as –log ___

Back 15

(H+)

Front 16

If a plant root absorbs more SO4
-2 from soil solution without an accompanying anion, the pH of the
surrounding soil solution will:

Back 16

increase

Front 17

As soil pH decreases, the concentration of which of the following three essential nutrients will increase?
a. Fe, Mo, B
b. Mo, Mn, Zn
c. Mo, Zn, Fe
d. Fe, Zn, Mn

Back 17

Fe, Zn, Mn

Front 18

Addition of ammonium nitrate fertilizers to soil in general will _________________ soil pH.

Back 18

decrease

Front 19

During your lab exercise on soil acidity,soil pH was determined by:
a. pH meter
b. dye
c. both a and b
d. none of the above

Back 19

c. both a and b

Front 20

Which of the following soil is relatively expected to have the highest CEC?
a. a sandy soil with 2% organic matter
b. a clay soil
c. a clay soil with 2% organic matter
d. all will have about the same.

Back 20

c. a clay soil with 2% organic matter

Front 21

The ability of a soil to resist changes in pH is called:

Back 21

buffering capacity

Front 22

The percent calcium carbonate equivalent of MgCO3 is:

Back 22

119

Front 23

Soil pH value is more or less a permanent property and can not be manipulated in less than ten years time.

Back 23

false

Front 24

You will be more apt to find salt affected soils in which of the following state?
a. Georgia
b. Montana
c. Mississippi
d. Alabama

Back 24

b. Montana

Front 25

Soil physical conditions began to deteriorate and crop yields began to decline several years after a farmer started irrigating his field. Which of the following most likely accounts for this situation?
a. high content of Ca and Mg in the irrigation water
b. failure to use conservation tillage to reduce salt accumulation at the soil surface
c. high SAR and ESP in the soil and irrigation water
d. excessive drainage of the soil

Back 25

c. high SAR and ESP in the soil and irrigation water

Front 26

The formula [Na+]/(0.5([Ca2+] + [Mg2+])1/2 is an expression of:

Back 26

SAR

Front 27

Gypsum is the most widely used chemical for the reclamation of sodic soils. What characteristic likely accounts for this popularity?

Back 27

Gypsum is abundant and low priced.

Front 28

Sodic soils generally have a poor physical condition. This is most likely due to:

Back 28

dispersal of the Na saturated soil colloids.

Front 29

Irrigation water that has an initial 20 ppm selenium concentration is used again and again at lower lying
agricultural fields. The selenium concentration in the irrigation drainage used by the last field would be:
a. less than 20 ppm
b. more than 20 ppm
c. 20 ppm
d. none of the above

Back 29

b. more than 20 ppm

Front 30

If a solution that contain 200 g of salt and 4000 g of water is allowed to evaporate to 50% of its original volume, the amount of salt left in the solution will be:

Back 30

200 g

Front 31

A micronutrient that can be toxic to plant at soil pH>8.5 is:
a. Al b. Zn c. Mn d. Mo

Back 31

d. Mo

Front 32

Biosphere II did not work as planned because the role of _____________ was neglected.

Back 32

microbes

Front 33

Since 1950s, more than 500 antibiotics have been isolated from:
a. nematodes
b. algae
c. actinomycetes
d. earthworm

Back 33

c. actinomycetes

Front 34

In general, microbial growth and activity is directly dependent on:

Back 34

soluble food

Front 35

In a given ecosystem, an organism A produces substance X that benefits organism B, but the substance has
no benefit for organism A. This association is a good example of:
a. parasitism
b. commensalism
c. amensalism
d. mutualism

Back 35

b. commensalism

Front 36

Genetically engineered microorganisms are:
a. are result of recombinant DNA
b. have no use at all
c. science fiction
d. rhizosphere.

Back 36

a. are result of recombinant DNA

Front 37

By any standard of measurements, earthworms have ____________ digestion system.
a. an efficient
b. an inefficient
c. super efficient
d. none of the above

Back 37

b. an inefficient

Front 38

Phosphorus will be fixed by ________ and _________ in alkaline soils and may not be available for plants.
a. Ca and Al
b. Al and Fe
c. Al and Mg
d. Ca and Mg

Back 38

d. Ca and Mg

Front 39

Under normal conditions, ____________ moves from the air atmosphere to soil atmosphere while __________ moves from soil atmosphere to air atmosphere.

Back 39

O2, CO2

Front 40

The quantity of soil air is related to:

Back 40

the proportion of pore space that is filled with air/water

Front 41

Anaerobic respiration of microorganisms produces significant amount of which of the following gas?
a. CH4 (methane)
b. O2
c. N2
d. CO2

Back 41

a. CH4 (methane)

Front 42

If the temperature of a soil were to increase from 10 to 20 degrees Celsius, you would expect the rate of
microbial activity (such as organic matter decomposition) to _______________.

Back 42

increase by 100%

Front 43

Which of the following process is true about soil temperature?
a. It fluctuates more in the subsoil soil than surface soil.
b. Subsoils are generally warmer in late fall and winter, but cooler in spring and summer.
c. In Alabama, soils facing north will be warmer than
those facing south during winter.
d. none of the above.

Back 43

b. Subsoils are generally warmer in late fall and winter, but cooler in spring and summer.

Front 44

The primary characteristics of subsoils that account for the ability of ground circulating heat pumps to moderate temperatures is?

Back 44

the high specific heat and low heat conductivity of the soil

Front 45

Benefit of wetlands does not include:
a. flood protection
b. methane production
c. water filtration
d. none of the above.

Back 45

b. methane production