Question 1

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 2

Char is made up of _____.

Accepted Answer

A) living organisms and cells woven through wood ash 
B) dead plant & animal tissues 
C) identifiable biomolecules 
D) pyrolized plant materials 
E) all of the above 
A) living organisms and cells woven through wood ash 
B) dead plant & animal tissues 
C) identifiable biomolecules 
D) pyrolized plant materials 
E) all of the above

Question 3

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 4

Humus is an important nutrient,essential for healthy plants.

Accepted Answer

A) True 
 B)False

Question 5

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 6

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 7

The labile and protected pools of organic matter have similarities in chemical structure.The protected nature of the protected humus is one reason its decomposition is slower.

Accepted Answer

A) True 
 B)False

Question 8

Which of the following added to a soil would be likely to result in the greatest level of soil organic matter after several years of decomposition?

Accepted Answer

A) 5 Mg of carbon in plant roots 
B) 5 Mg of carbon in plant tops 
C) the manure produced by feeding cattle 5 Mg carbon in plant residues 
D) the compost produced by composting 5 Mg of plant leaf material. 
A) 5 Mg of carbon in plant roots 
B) 5 Mg of carbon in plant tops 
C) the manure produced by feeding cattle 5 Mg carbon in plant residues 
D) the compost produced by composting 5 Mg of plant leaf material.

Question 9

Soil organic matter 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 10

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

Accepted Answer

A) True 
 B)False

Question 11

Aridisols generally contain more organic matter than Mollisols.

Accepted Answer

A) True 
 B)False

Question 12

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 13

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 14

The main contributions of the active fraction of soil organic matter are increased CEC and water holding capacity of the soil.

Accepted Answer

A) True 
 B)False

Question 15

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 16

Detritus 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 17

Mineralization of soil organic matter results in the addition of inorganic nutrient ions to the soil solution.

Accepted Answer

A) True 
 B)False

Question 18

The most active decomposers of freshly added organic materials are able to sustain themselves by slowly attacking stable soil organic matter 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 19

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 20

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

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

Char is made up of _____.

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

Humus is an important nutrient,essential for healthy plants.

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?

The labile and protected pools of organic matter have similarities in chemical structure.The protected nature of the protected humus is one reason its decomposition is slower.

Which of the following added to a soil would be likely to result in the greatest level of soil organic matter after several years of decomposition?

Soil organic matter consists of ______.

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

Aridisols generally contain more organic matter than Mollisols.

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

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 main contributions of the active fraction of soil organic matter are increased CEC and water holding capacity of the soil.

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

Detritus consists of ______.

Mineralization of soil organic matter results in the addition of inorganic nutrient ions to the soil solution.

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

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

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 ______.

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

Soils of Dry Regionsalkalinity,salinity and Sodicity

Organisms and Ecology of the Soil

Nitrogen and Sulfur Economy of Soils

Soil Phosphorus and Potassium

Calcium,magnesium and Trace Elements

Practical Nutrient Management

Soil Erosion and Its Control

Soils and Chemical Pollution

Geographic Information About Soils

Prospects for Global Soil Quality As Affected by Human Activities

Filters

Exam 12: Soil Organic Matter

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

Char is made up of _____.

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

Humus is an important nutrient,essential for healthy plants.

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?

The labile and protected pools of organic matter have similarities in chemical structure.The protected nature of the protected humus is one reason its decomposition is slower.

Which of the following added to a soil would be likely to result in the greatest level of soil organic matter after several years of decomposition?

Soil organic matter consists of ______.

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

Aridisols generally contain more organic matter than Mollisols.

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

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 main contributions of the active fraction of soil organic matter are increased CEC and water holding capacity of the soil.

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

Detritus consists of ______.

Mineralization of soil organic matter results in the addition of inorganic nutrient ions to the soil solution.

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

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

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 ______.

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

Soils of Dry Regionsalkalinity,salinity and Sodicity

Organisms and Ecology of the Soil

Nitrogen and Sulfur Economy of Soils

Soil Phosphorus and Potassium

Calcium,magnesium and Trace Elements

Practical Nutrient Management

Soil Erosion and Its Control

Soils and Chemical Pollution

Geographic Information About Soils

Prospects for Global Soil Quality As Affected by Human Activities

Filters