Question 1

When native prairie soils are brought under cultivation, the fraction of soil organic matter which disappears most quickly is the passive fraction.

Accepted Answer

A) True 
 B)False  False

Question 2

Nearly all organic compounds from which living beings are made have as their backbone, chains or rings of _____ atoms.

Accepted Answer

A)  aluminum 
B)  oxygen 
C)  carbon 
D)  nitrogen 
E)  none of the above 
A)  aluminum 
B)  oxygen 
C)  carbon 
D)  nitrogen 
E)  none of the above C

Question 3

To avoid a nitrate depression period when it is added to a garden soil, about how many kg of nitrogen must be added to a load of grass clippings that contains 1000 kg of C and 25 kg of N?

Accepted Answer

A)  15 
B)  35 
C)  50 
D)  75 
E)  100 
A)  15 
B)  35 
C)  50 
D)  75 
E)  100 A

Question 4

When fresh plant residues are added to soils, the "priming effect" may result in the decomposition of _______.

Accepted Answer

A)  stable humus 
B)  sugars and starch 
C)  waxes and fats 
D)  lignin and cellulose 
E)  proteins and other nitrogen-rich compounds 
A)  stable humus 
B)  sugars and starch 
C)  waxes and fats 
D)  lignin and cellulose 
E)  proteins and other nitrogen-rich compounds

Question 5

Allelopathic chemicals, once added to soil, usually make the affected soil unsuitable for any plant life for periods of years.

Accepted Answer

A) True 
 B)False

Question 6

One would expect well drained soils to have the highest organic matter contents where the climate is _______.

Accepted Answer

A)  warm and dry 
B)  warm and humid 
C)  cool and dry 
D)  cool and humid 
A)  warm and dry 
B)  warm and humid 
C)  cool and dry 
D)  cool and humid

Question 7

Humus indirectly affects plant growth through its effects on soil physical and chemical properties, but humic substances have not been shown to affect plant growth processes directly.

Accepted Answer

A) True 
 B)False

Question 8

The priming effect refers to the excretion of growth promoting substance by certain bacteria during decomposition of fresh organic residues.

Accepted Answer

A) True 
 B)False

Question 9

Under natural vegetation, about 60 to 90% of soil organic matter is in the _____fraction.

Accepted Answer

A)  active 
B)  slow 
C)  passive 
A)  active 
B)  slow 
C)  passive

Question 10

Soils with thick horizons consisting mainly (> 30% by weight) of organic matter and that form in topographic depressions or low-lying places usually belong to the order ______.

Accepted Answer

A)  Alfisols 
B)  Vertisols 
C)  Histosols 
D)  Umbrasols 
E)  Spodosols 
A)  Alfisols 
B)  Vertisols 
C)  Histosols 
D)  Umbrasols 
E)  Spodosols

Question 11

Non-humic substances formed during organic matter decomposition probably play a more important role than do humic compounds in the mineralization of N and S as well as in the solubilization of iron and other micronutrients.

Accepted Answer

A) True 
 B)False

Question 12

Biomass consists of ______.

Accepted Answer

A)  living organisms and cells 
B) dead tissues and wastes. 
C)  identifiable biomolecules 
D) polymerized, non-identifiable molecules. 
E)  all of the above 
A)  living organisms and cells 
B) dead tissues and wastes. 
C)  identifiable biomolecules 
D) polymerized, non-identifiable molecules. 
E)  all of the above

Question 13

Fulvic acids are a major type of non-humic substances.

Accepted Answer

A) True 
 B)False

Question 14

As decomposition of added organic material proceeds, the C/N ratio in the remaining undecomposed material steadily increases.

Accepted Answer

A) True 
 B)False

Question 15

Humus is an important nutrient, essential for healthy plants.

Accepted Answer

A) True 
 B)False

Question 16

Aridisols generally contain more organic matter than Mollisols.

Accepted Answer

A) True 
 B)False

Question 17

Which of the following pools contain the largest amount of the world's carbon?

Accepted Answer

A)  soil 
B)  vegetation 
C)  atmosphere 
D)  animals 
A)  soil 
B)  vegetation 
C)  atmosphere 
D)  animals

Question 18

Which of the following is (are) major sources of the carbon dioxide now being added to the atmosphere in excess of the amount taken out by plants?

Accepted Answer

A)  loss of soil organic matter 
B)  burning of fossil fuels 
C)  destruction of natural forests 
D)  all of the above 
E)  none of the above 
A)  loss of soil organic matter 
B)  burning of fossil fuels 
C)  destruction of natural forests 
D)  all of the above 
E)  none of the above

Question 19

Sandy soils generally are higher in organic matter than fine textured soils.

Accepted Answer

A) True 
 B)False

Question 20

The cation capacity of soil humus is two to three times greater than that of an equal volume of high CEC silicate clays.

Accepted Answer

A) True 
 B)False

When native prairie soils are brought under cultivation, the fraction of soil organic matter which disappears most quickly is the passive fraction.

Nearly all organic compounds from which living beings are made have as their backbone, chains or rings of _____ atoms.

To avoid a nitrate depression period when it is added to a garden soil, about how many kg of nitrogen must be added to a load of grass clippings that contains 1000 kg of C and 25 kg of N?

When fresh plant residues are added to soils, the "priming effect" may result in the decomposition of _______.

Allelopathic chemicals, once added to soil, usually make the affected soil unsuitable for any plant life for periods of years.

One would expect well drained soils to have the highest organic matter contents where the climate is _______.

Humus indirectly affects plant growth through its effects on soil physical and chemical properties, but humic substances have not been shown to affect plant growth processes directly.

The priming effect refers to the excretion of growth promoting substance by certain bacteria during decomposition of fresh organic residues.

Under natural vegetation, about 60 to 90% of soil organic matter is in the _____fraction.

Soils with thick horizons consisting mainly (> 30% by weight) of organic matter and that form in topographic depressions or low-lying places usually belong to the order ______.

Non-humic substances formed during organic matter decomposition probably play a more important role than do humic compounds in the mineralization of N and S as well as in the solubilization of iron and other micronutrients.

Biomass consists of ______.

Fulvic acids are a major type of non-humic substances.

As decomposition of added organic material proceeds, the C/N ratio in the remaining undecomposed material steadily increases.

Humus is an important nutrient, essential for healthy plants.

Aridisols generally contain more organic matter than Mollisols.

Which of the following pools contain the largest amount of the world's carbon?

Which of the following is (are) major sources of the carbon dioxide now being added to the atmosphere in excess of the amount taken out by plants?

Sandy soils generally are higher in organic matter than fine textured soils.

The cation capacity of soil humus is two to three times greater than that of an equal volume of high CEC silicate clays.

The Soils Around Us

Formation of Soils From Parent Materials

Soil Classification

Soil Architecture and Physical Properties

Soil Water: Characteristics and Behavior

Soil and the Hydrologic Cycle

Soil Aeration and Temperature

The Colloidal Fraction: Seat of Soil Chemical and Physical Activity

Soil Acidity, Alkalinity, Aridity and Salinity

Organisms and Ecology of the Soil

Nutrient Cycles and Soil Fertility

Practical Nutrient Management

Soil Erosion and Its Control

Soils and Chemical Pollution

Filters

Exam 11: Soil Organic Matter Overview

When native prairie soils are brought under cultivation, the fraction of soil organic matter which disappears most quickly is the passive fraction.

Nearly all organic compounds from which living beings are made have as their backbone, chains or rings of _____ atoms.

To avoid a nitrate depression period when it is added to a garden soil, about how many kg of nitrogen must be added to a load of grass clippings that contains 1000 kg of C and 25 kg of N?

When fresh plant residues are added to soils, the "priming effect" may result in the decomposition of _______.

Allelopathic chemicals, once added to soil, usually make the affected soil unsuitable for any plant life for periods of years.

One would expect well drained soils to have the highest organic matter contents where the climate is _______.

Humus indirectly affects plant growth through its effects on soil physical and chemical properties, but humic substances have not been shown to affect plant growth processes directly.

The priming effect refers to the excretion of growth promoting substance by certain bacteria during decomposition of fresh organic residues.

Under natural vegetation, about 60 to 90% of soil organic matter is in the _____fraction.

Soils with thick horizons consisting mainly (> 30% by weight) of organic matter and that form in topographic depressions or low-lying places usually belong to the order ______.

Non-humic substances formed during organic matter decomposition probably play a more important role than do humic compounds in the mineralization of N and S as well as in the solubilization of iron and other micronutrients.

Biomass consists of ______.

Fulvic acids are a major type of non-humic substances.

As decomposition of added organic material proceeds, the C/N ratio in the remaining undecomposed material steadily increases.

Humus is an important nutrient, essential for healthy plants.

Aridisols generally contain more organic matter than Mollisols.

Which of the following pools contain the largest amount of the world's carbon?

Which of the following is (are) major sources of the carbon dioxide now being added to the atmosphere in excess of the amount taken out by plants?

Sandy soils generally are higher in organic matter than fine textured soils.

The cation capacity of soil humus is two to three times greater than that of an equal volume of high CEC silicate clays.

The Soils Around Us

Formation of Soils From Parent Materials

Soil Classification

Soil Architecture and Physical Properties

Soil Water: Characteristics and Behavior

Soil and the Hydrologic Cycle

Soil Aeration and Temperature

The Colloidal Fraction: Seat of Soil Chemical and Physical Activity

Soil Acidity, Alkalinity, Aridity and Salinity

Organisms and Ecology of the Soil

Nutrient Cycles and Soil Fertility

Practical Nutrient Management

Soil Erosion and Its Control

Soils and Chemical Pollution

Filters