18 Questions
What is the primary cause of lowering the pH of calcareous soils under submerged conditions?
Production of carbonic acid during organic matter decomposition
Which of the following processes is responsible for the formation of nitric acid (HNO3) in the soil?
Nitrification
Which type of soil acidity is determined by measuring the soil pH using a pH meter?
Active acidity
Which of the following is the primary factor responsible for the formation of sulfuric acid (H2SO4) in the soil?
Microbial oxidation of sulfur compounds
Which type of soil acidity is determined by titration and provides information on how much lime to apply?
Reserve acidity
Which of the following is a common characteristic of plants that prefer slightly acidic soil conditions?
They require higher soil pH for optimal growth
What is the relationship between pH and pOH according to the text?
pH + pOH = 14
Which ion is responsible for soil alkalinity according to the text?
OH-
What is the definition of pH according to the text?
The negative logarithm of the hydrogen ion concentration
Which of the following pH ranges is considered extremely acidic according to the text?
pH < 4.5
Which of the following is a source of soil acidity according to the text?
Adsorbed hydrogen ions
What is the relationship between pH and redox potential in soils?
Decreasing pH increases redox potential
What is the main effect of soil sodicity on plant growth?
Reduced water uptake and ion-specific toxicities
How does soil sodicity degrade soil properties?
By weakening the bond between soil particles
What is the reference electrode used to measure redox potential?
Platinum electrode with a saturated calomel electrode
What is the redox potential range for oxidized soils?
+400 to +700 mV
What can be estimated from the redox potential measurement of a soil?
Whether the soil is aerobic, anaerobic, and the presence of reduced or oxidized chemical compounds
What is the range of redox potentials for highly reduced soils?
-250 to -300 mV
Learn about how excess salts can reduce plant growth by altering water uptake and causing ion-specific toxicities or imbalances. Discover how soil sodicity, characterized by a high proportion of sodium ions, degrades soil properties and weakens the bond between soil particles. Explore the concept of redox potential in describing a system's overall reducing or oxidizing capacity.
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