10: Importance of Soil pH 1

Question 1

Soil pH

What does it measure?
What does a high or low pH mean in terms of relative concentrations of H+ and OH- ions?

Answer 1

Soil acidity/alkalinity, which is the measure of H+ or OH- in the soil solution

Low pH means higher concentration of H+ ions, high pH means higher concentration of OH- ions

Question 2

Why is soil pH important?

Answer 2

Affects:
1. Solubility of elements, including nutrients and toxic elements
2. CEC
2. The activity of soil organisms

Question 3

What pH range has the highest nutrient availability?

Answer 3

Highest nutrient availability at slightly acidic (5.5-6.5) pH

Question 4

pH effect on CEC

Answer 4

pH can change the charges in colloids

Question 5

pH effect on activity of soil organisms

How do fungi and bacteria do the same or worse at different pH levels?

Answer 5

Fungi are tolerant to pH changes
Bacteria are sensitive to low pH

Question 6

How does CEC and AEC change with pH?

Answer 6

Cation exchange capacity (CEC) increases as pH increases
Anion exchange capacity (AEC) decreases as pH increases