Chemical Characteristics of Soil

What are the smallest and most chemically active particles in soil?

• Clay

• Sand

• Silt

• Gravel

What is flocculation?

• Clustering of soil particles

• Separation of soil particles

• Absorption of water by soil

• Release of nutrients

What are cations?

• Negatively charged ions

• Positively charged ions

• Neutral ions

• Organic compounds

What does cation exchange capacity (CEC) refer to?

• The ability to absorb anions

• The quantity of cations that can be adsorbed by soil

• The amount of water retained in soil

• The pH level of soil

What factor has the highest CEC value?

• Clay

• Sand

• Humus

• Silt

How does pH affect cation availability?

• More cations are available at lower pH levels

• Fewer cations are available at lower pH levels

• pH has no effect on cation availability

• Cations are only available at neutral pH

What is the optimum pH level for crop growth?

• 4.5 to 5.5

• 5.5 to 6.5

• 6.5 to 7.5

• 7.5 to 8.5

What is liming?

• Spreading ground limestone on soil

• Adding organic matter to soil

• Irrigating soil with water

• Removing excess salts from soil

What is the total neutralising value of ground limestone for agricultural use?

• No less than 80%

• No less than 90%

• No less than 70%

• No less than 60%