Question 1

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 2

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 3

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

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

Poorly drained soils generally contain more organic matter than well drained soils.

Accepted Answer

A) True 
 B)False

Question 7

Aridisols generally contain more organic matter than Mollisols.

Accepted Answer

A) True 
 B)False

Question 8

The species of microorganisms that are able to sustain themselves by slowly attacking stable soil organic matter are the most active decomposers of freshly added organic materials because of the head start they enjoy over other organisms which were present only in inactive forms prior to the addition.

Accepted Answer

A) True 
 B)False

Question 9

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 10

Removing all the straw with the harvest of paddy rice would increase the amount of methane produced by the paddy soil microorganisms.

Accepted Answer

A) True 
 B)False

Question 11

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

Accepted Answer

A) True 
 B)False

Question 12

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 13

Practices that increase the soil organic matter level generally have favorable effects on the chemical and biological properties of soils, but have little or no effect on soil physical properties.

Accepted Answer

A) True 
 B)False

Question 14

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

Question 15

After drying to eliminate the water in plant litter, which two elements account for about 80% of the dry weight?

Accepted Answer

A) N and C 
B) N and S 
C) C and H 
D) C and O 
E) Ca and C 
A) N and C 
B) N and S 
C) C and H 
D) C and O 
E) Ca and C

Question 16

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 17

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

Accepted Answer

A) True 
 B)False

Question 18

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 19

Alcohols, methane and organic acids of various kinds often accumulate as a result of ______ decomposition of residues in soil.

Accepted Answer

A) nitrogen-limited 
B) acidic 
C) fungal 
D) anaerobic 
E) abiotic 
A) nitrogen-limited 
B) acidic 
C) fungal 
D) anaerobic 
E) abiotic

Question 20

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

Biomass consists of ______.

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

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

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.

Poorly drained soils generally contain more organic matter than well drained soils.

Aridisols generally contain more organic matter than Mollisols.

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

Removing all the straw with the harvest of paddy rice would increase the amount of methane produced by the paddy soil microorganisms.

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

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.

Practices that increase the soil organic matter level generally have favorable effects on the chemical and biological properties of soils, but have little or no effect on soil physical properties.

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

After drying to eliminate the water in plant litter, which two elements account for about 80% of the dry weight?

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.

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

Alcohols, methane and organic acids of various kinds often accumulate as a result of ______ decomposition of residues in soil.

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

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

Soil Colloids: Seat of Soil Chemical and Physical Activity

Soil Acidity

Soils of Dry Regions: Alkalinity, Salinity, and Sodicity

Organisms and Ecology of the Soil

Nitrogen and Sulfur Economy of Soils

Soil Phosphorus and Potassium

Micronutrients and Other Trace Elements

Practical Nutrient Management

Soil Erosion and Its Control

Soils and Chemical Pollution

Geographic Soils Information

Prospects for Global Soil Quality

Filters

Exam 12: Soil Organic Matter

Biomass consists of ______.

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

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

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.

Poorly drained soils generally contain more organic matter than well drained soils.

Aridisols generally contain more organic matter than Mollisols.

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

Removing all the straw with the harvest of paddy rice would increase the amount of methane produced by the paddy soil microorganisms.

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

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.

Practices that increase the soil organic matter level generally have favorable effects on the chemical and biological properties of soils, but have little or no effect on soil physical properties.

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

After drying to eliminate the water in plant litter, which two elements account for about 80% of the dry weight?

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.

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

Alcohols, methane and organic acids of various kinds often accumulate as a result of ______ decomposition of residues in soil.

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

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

Soil Colloids: Seat of Soil Chemical and Physical Activity

Soil Acidity

Soils of Dry Regions: Alkalinity, Salinity, and Sodicity

Organisms and Ecology of the Soil

Nitrogen and Sulfur Economy of Soils

Soil Phosphorus and Potassium

Micronutrients and Other Trace Elements

Practical Nutrient Management

Soil Erosion and Its Control

Soils and Chemical Pollution

Geographic Soils Information

Prospects for Global Soil Quality

Filters