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International CCA Exam - Soil and Water
Management Competency Areas
Questions and Correct Answers/ Latest
Update / Already Graded
Define anion and cation.
Ans: Anion: negatively charged atom or molecule. Examples
include phosphate, sulfate, nitrate, and chloride.
Cation: A positively charged atom or molecule. Examples
include calcium, magnesium, sodium, potassium and
ammonium.
Define cation exchange capacity and anion exchange capacity.
Ans: CEC is amount of positively charged cations which can be
held by a given weight of soil. Cations are held by negative
charges in clay and organic matter.
AEC is amount of negatively charged anions which can be held
by a given weight of soil. Anions are held by positive charges in
clay and organic matter.
Describe how the % of clay, type of clay, % organic matter, and pH
influence CEC.
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Ans: Different types of clay (vermiculite, montmorillonite,
illite, kaolinite) have different CECs.
Organic matter has very high CEC. The higher % of OM a soil
has, the higher CEC it has.
% of clay also influences the CEC of a soil. A large % of kaolinite
will have a lower CEC than a large % of vermiculite, but
generally as % of clay increases so does CEC.
pH can affect CEC through the pH dependent charge on organic
matter and some clays. As pH increases, CEC increases and AEC
decreases.
Describe how parent material and mineralogy influence background
fertility.
Ans: They determine soil properties such as pH, CEC, AEC,
soluble salts, clay mineralogy, and organic matter which
influence background fertility.
Differentiate saline, sodic/natric, calcareous, acidic and alkaline soils.
Ans: Saline: soil contains sufficient salt to impair plant growth.
Soils that have an EC greater than or equal to 0.4 siemens per
meter in saturation extract are saline.
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Sodic/Natric: soil has 13-15% of CEC occupied by sodium. These
soils have poor structure and accompanying poor plant growth.
Calcareous: soils contain free calcium carbonate.
Acidic: Soils with a pH less than 7
Alkaline: Soils with a pH greater than 7
Define soil texture.
Ans: Percentages of sand, silt and clay in a soil.
Describe how particle size affects surface area and reactivity of soils.
Ans: Smaller particles (such as clay) have much larger surface
area than larger particles (sand).
Soils with higher surface areas are more reactive because of
higher charge as well as more surfaces where reactions can
occur.
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Describe how soil texture affects the water holding capacity, amount
of plant available water, and wilting point of soils.
Ans: Distribution of pore sizes impacts drainage and plant
available water. Small pores retain water for plant use, larger
pores allow water to drain and oxygen to enter the soil.
Intermediate textures (loam, silt loam, clay loam) have greatest
capacity to store plant available water. Sandy soils have small
field capacity and wilting point values. Cl ay soils retain large
amounts of water at field capacity.
Define soil structure.
Ans: Arrangement of soil particles into aggregates of varying
degrees of coherence.
Blocky soil structure
Ans: Irregular, six sided aggregates.
Angular blocky = sharp edges
Subangular blocky = rounded edges
Single grain soil structure
All rights reserved © 2025/ 2026 |
International CCA Exam - Soil and Water
Management Competency Areas
Questions and Correct Answers/ Latest
Update / Already Graded
Define anion and cation.
Ans: Anion: negatively charged atom or molecule. Examples
include phosphate, sulfate, nitrate, and chloride.
Cation: A positively charged atom or molecule. Examples
include calcium, magnesium, sodium, potassium and
ammonium.
Define cation exchange capacity and anion exchange capacity.
Ans: CEC is amount of positively charged cations which can be
held by a given weight of soil. Cations are held by negative
charges in clay and organic matter.
AEC is amount of negatively charged anions which can be held
by a given weight of soil. Anions are held by positive charges in
clay and organic matter.
Describe how the % of clay, type of clay, % organic matter, and pH
influence CEC.
All rights reserved © 2025/ 2026 |
, Page |2
Ans: Different types of clay (vermiculite, montmorillonite,
illite, kaolinite) have different CECs.
Organic matter has very high CEC. The higher % of OM a soil
has, the higher CEC it has.
% of clay also influences the CEC of a soil. A large % of kaolinite
will have a lower CEC than a large % of vermiculite, but
generally as % of clay increases so does CEC.
pH can affect CEC through the pH dependent charge on organic
matter and some clays. As pH increases, CEC increases and AEC
decreases.
Describe how parent material and mineralogy influence background
fertility.
Ans: They determine soil properties such as pH, CEC, AEC,
soluble salts, clay mineralogy, and organic matter which
influence background fertility.
Differentiate saline, sodic/natric, calcareous, acidic and alkaline soils.
Ans: Saline: soil contains sufficient salt to impair plant growth.
Soils that have an EC greater than or equal to 0.4 siemens per
meter in saturation extract are saline.
All rights reserved © 2025/ 2026 |
, Page |3
Sodic/Natric: soil has 13-15% of CEC occupied by sodium. These
soils have poor structure and accompanying poor plant growth.
Calcareous: soils contain free calcium carbonate.
Acidic: Soils with a pH less than 7
Alkaline: Soils with a pH greater than 7
Define soil texture.
Ans: Percentages of sand, silt and clay in a soil.
Describe how particle size affects surface area and reactivity of soils.
Ans: Smaller particles (such as clay) have much larger surface
area than larger particles (sand).
Soils with higher surface areas are more reactive because of
higher charge as well as more surfaces where reactions can
occur.
All rights reserved © 2025/ 2026 |
, Page |4
Describe how soil texture affects the water holding capacity, amount
of plant available water, and wilting point of soils.
Ans: Distribution of pore sizes impacts drainage and plant
available water. Small pores retain water for plant use, larger
pores allow water to drain and oxygen to enter the soil.
Intermediate textures (loam, silt loam, clay loam) have greatest
capacity to store plant available water. Sandy soils have small
field capacity and wilting point values. Cl ay soils retain large
amounts of water at field capacity.
Define soil structure.
Ans: Arrangement of soil particles into aggregates of varying
degrees of coherence.
Blocky soil structure
Ans: Irregular, six sided aggregates.
Angular blocky = sharp edges
Subangular blocky = rounded edges
Single grain soil structure
All rights reserved © 2025/ 2026 |
