Chapter 12

Question 1

Agricultural operations can cause modifications to the C horizon.

Answer 1

False

Question 2

Soils in wet tropical regions tend to have high organic matter and distinct profiles.

Answer 2

False

Question 3

Weathered rock can be a source of essential minerals for plants.

Answer 3

True

Question 4

Plants with low C:N ratios decay rapidly.

Answer 4

True

Question 5

Sawdust added to soil can cause nitrogen deficiency.

Answer 5

True

Question 6

Organic matter has a positive charge.

Answer 6

False

Question 7

Higher earthworm populations are achieved in conventional tillage in comparison to no-till.

Answer 7

False

Question 8

Plants infected with mycorrhizal fungi can absorb phosphorus better than noninfected plants.

Answer 8

True

Question 9

Productive soils are densely packed.

Answer 9

False

Question 10

A plant will extract water at field capacity until it reaches the permanent wilting point.

Answer 10

True

Question 11

Sandy soils drain at a faster rate than clay soils.

Answer 11

True

Question 12

Soils that are fertile and hold nutrients will have a low cation exchange capacity.

Answer 12

False

Question 13

The pH of a soil is important because it influences the availability of plant nutrients.

Answer 13

True

Question 14

Most crops grow well in soils with high salinity.

Answer 14

False

Question 15

Crop yields will increase indefinitely in response to increasing fertilizer.

Answer 15

False

Question 16

Synthetic fertilizers are used to provide organic matter to the soil.

Answer 16

False

Question 17

Geologic erosion occurs at a faster rate than soil formation.

Answer 17

False

Question 18

Erosion can leave behind less fertile subsoils.

Answer 18

True

Question 19

How thick does the soil layer tend to be in agricultural regions?
A. 3 to 4 inches
B. 4 to 12 inches
C. 3 to 4 feet
D. 4 to 12 feet

Answer 19

C. 3 to 4 feet

Question 20

A vertical section through the soil extending from the surface to the unweathered rock is best described as the:
A. crust
B. horizon
C. profile
D. core

Answer 20

C. profile

Question 21

The topsoil is also known as the
A. A horizon
B. B horizon
C. C horizon
D. O horizon

Answer 21

A. A horizon

Question 22

The subsoil is also known as the 
A. A horizon
B. B horizon
C. C horizon
D. O horizon

Answer 22

B. B horizon

Question 23

Which horizon has the highest amount of organic matter?
A. A horizon
B. B horizon
C. C horizon
D. O horizon

Answer 23

O horizon

Question 24

Which of the following is one of the most important soils in agricultural production?
A. aridisol
B. mollisol
C. gelisol
D. spodosol

Answer 24

B. mollisol

Question 25

``` Which is the predominant parent material for soils? A. igneous rock B. sedimentary rock C. metamorphic rock D. slate rock ```

Answer 25

B. sedimentary rock

Question 26

``` The fineness or coarseness of a soil is called: A. soil field capacity B. soil structure C. soil aggregation D. soil texture ```

Answer 26

D. soil texture

Question 27

``` Sand and silt are chemically composed mostly of: A. silica B. potassium C. soil aggregation D. soil texture ```

Answer 27

A. silica

Question 28

``` Which soil particle contributes most to plant nutrition? A. sand B. silt C. clay D. silica ```

Answer 28

C. clay

Question 29

``` The clustering of soil particles into various shapes is called: A. soil field capacity B. soil structure C. soil salinity D. soil texture ```

Answer 29

B. soil structure

Question 30

``` The pH range that most field crops grow best at is: A. 4-5 B. 5-6 C. 6-7 D. 7-8 ```

Answer 30

C. 6-7

Question 31

``` Which of the following is an index that rates soils for intensive agricultural production on a 0 to 100-value scale? A. Crop Agricultural Index B. Crop Productivity Index C. Crop Parameter Index D. Crop Suitability Index ```

Answer 31

B. Crop Productivity Index

Question 32

``` One distinction between organic and inorganic fertilizers is that organic fertilizers contain: A. carbon B. nitrogen C. potassium D. lime ```

Answer 32

A. carbon

Question 33

``` Which of the following fertilizer nutrients is NOT obtained from mining? A. phosphorus B. nitrogen C. potassium D. calcium ```

Answer 33

B. nitrogen

Question 34

``` Limestone is applied to soil to: A. increase organic matter B. add potassium C. add phosphorus D. increase soil pH ```

Answer 34

D. increase soil pH