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International Certified Crop Advisor Exam
Soil and Water Management Questions
and Correct Answers/ Latest Update /
Already Graded
Anion definition
Ans: Negatively charged atom or molecule
Cation definition
Ans: Positively charged atom or molecule
Cation exchange capacity definition
Ans: Amount of positively charged cations which can be held
by a given weight of soil. Cations are held by negative charges
in clay and OM. Meq/100g soil
Anion exchange capacity definition
Ans: Amount of negatively charged anions which can be held
by a given weight of soil. Anions are held by positive charges in
clay and OM. Meq/g soil
Soil factors that influence CEC
All rights reserved © 2025/ 2026 |
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Ans: Percent clay, type of clay, amount of OM, and soil pH
Estimate of CEC of pure SOM
Ans: 200
Estimate of CEC of pure vermiculite clay
Ans: 150
Estimate of CEC of pure montmorillonite clay
Ans: 100
Estimate of CEC of illite clay
Ans: 30
Estimate of CEC of kaolinite clay
Ans: 10
Relationship between CEC and pH
Ans: As pH increases CEC increases (AEC decreases)
All rights reserved © 2025/ 2026 |
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Explain how K and NH4+ can become fixed in soils
Ans: Some clay minerals have "holes" on their surface about
the size of these molecules. When these ions enter those spaces
the clay collapses around the cations "fixing" them.
What soil properties are determined by parent material and
mineralogy
Ans: pH, CEC, AEC, soluble salts, clay mineralogy, and OM
What soil properties influence background fertility
Ans: pH, CEC, AEC, soluble salts, clay mineralogy, and OM
Definition of saline soils
Ans: Have an electrical conductivity greater than or equal to
0.4 Siemens per meter in the saturation extract. They have
sufficient soluble salt to impair crop growth
Definition of sodic/natric soils
Ans: 13-15 percent or more of the CEC occupied by sodium.
Poor structure and accompanying poor plant growth
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Definition of saline-sodic soils
Ans: ECs>0.4 Siemens per meter and from 13-15 percent of the
CEC occupied by sodium. Good physical properties until salt is
removed
Definition of calcareous soils
Ans: Contain free calcium carbonate
Define acidic soils
Ans: pH less than 7
Define alkaline soil
Ans: pH over 7
Particle size of gravel
Ans: >2 mm
Particle size of sand
Ans: 2-0.05 mm
All rights reserved © 2025/ 2026 |
International Certified Crop Advisor Exam
Soil and Water Management Questions
and Correct Answers/ Latest Update /
Already Graded
Anion definition
Ans: Negatively charged atom or molecule
Cation definition
Ans: Positively charged atom or molecule
Cation exchange capacity definition
Ans: Amount of positively charged cations which can be held
by a given weight of soil. Cations are held by negative charges
in clay and OM. Meq/100g soil
Anion exchange capacity definition
Ans: Amount of negatively charged anions which can be held
by a given weight of soil. Anions are held by positive charges in
clay and OM. Meq/g soil
Soil factors that influence CEC
All rights reserved © 2025/ 2026 |
, Page |2
Ans: Percent clay, type of clay, amount of OM, and soil pH
Estimate of CEC of pure SOM
Ans: 200
Estimate of CEC of pure vermiculite clay
Ans: 150
Estimate of CEC of pure montmorillonite clay
Ans: 100
Estimate of CEC of illite clay
Ans: 30
Estimate of CEC of kaolinite clay
Ans: 10
Relationship between CEC and pH
Ans: As pH increases CEC increases (AEC decreases)
All rights reserved © 2025/ 2026 |
, Page |3
Explain how K and NH4+ can become fixed in soils
Ans: Some clay minerals have "holes" on their surface about
the size of these molecules. When these ions enter those spaces
the clay collapses around the cations "fixing" them.
What soil properties are determined by parent material and
mineralogy
Ans: pH, CEC, AEC, soluble salts, clay mineralogy, and OM
What soil properties influence background fertility
Ans: pH, CEC, AEC, soluble salts, clay mineralogy, and OM
Definition of saline soils
Ans: Have an electrical conductivity greater than or equal to
0.4 Siemens per meter in the saturation extract. They have
sufficient soluble salt to impair crop growth
Definition of sodic/natric soils
Ans: 13-15 percent or more of the CEC occupied by sodium.
Poor structure and accompanying poor plant growth
All rights reserved © 2025/ 2026 |
, Page |4
Definition of saline-sodic soils
Ans: ECs>0.4 Siemens per meter and from 13-15 percent of the
CEC occupied by sodium. Good physical properties until salt is
removed
Definition of calcareous soils
Ans: Contain free calcium carbonate
Define acidic soils
Ans: pH less than 7
Define alkaline soil
Ans: pH over 7
Particle size of gravel
Ans: >2 mm
Particle size of sand
Ans: 2-0.05 mm
All rights reserved © 2025/ 2026 |
