1. Lesson 3.2 Principles of pH
What is pH?
Introduction to Agriculture, Food, and Natural Resources
Unit 3 Lesson 3.2 Principles of pH
What is pH?
Lesson 3.2 Principles of pH
Curriculum for Agricultural Science Education
Copyright 2011

2. What is pH? pH is the measure of acidity or alkalinity in a soil.
Introduction to Agriculture, Food, and Natural Resources
Unit 3 Lesson 3.2 Principles of pH
What is pH?
pH is the measure of acidity or alkalinity in a soil.
Acid is a term used for a substance with a pH value less than 7.0.
Alkaline (aka, Base) is a term used for a substance with a pH value greater than 7.0.
Definitions are essential for pH concepts.
Curriculum for Agricultural Science Education
Copyright 2011

3. pH Scale pH is measured on a scale of 0 - 14
What is pH?
Introduction to Agriculture, Food, and Natural Resources
Unit 3 Lesson 3.2 Principles of pH
pH Scale
pH is measured on a scale of
pH value of 7.0 is neutral
Curriculum for Agricultural Science Education
Copyright 2011

4. What is pH?
Introduction to Agriculture, Food, and Natural Resources
Unit 3 Lesson 3.2 Principles of pH
pH Scale
The pH scale is special in that each pH point multiplies the pH factor by 10.
For example:
A pH of 5.0 is 10 times more acidic than pH 6.0 and 100 times more acidic than pH 7.0.
Distilled water would be an example of a pH neutral substance.
Let’s try another pH calculation:
How many times more alkali is 9.0 from 6.0? (1000 times)
Curriculum for Agricultural Science Education
Copyright 2011

5. Who cares about pH? Plant producers Animal producers
What is pH?
Introduction to Agriculture, Food, and Natural Resources
Unit 3 Lesson 3.2 Principles of pH
Who cares about pH?
Plant producers
A correct soil pH allows plants to uptake soil nutrients required for growth and health.
Certain soil nutrients become unavailable at different pH levels.
Animal producers
Nutrient uptake in digestion
Agricultural scientists
Food preservation
pH is an important consideration for many agricultural industries because pH is important in the nutrient availability in plants and animals. It influences the efficiency of plants to utilize fertilizers added for optimal growth. If pH is not optimal for the plant, many nutrients added in the form of fertilizer are washed away rather than used for plant growth and health.
Curriculum for Agricultural Science Education
Copyright 2011

6. What is pH?
Introduction to Agriculture, Food, and Natural Resources
Unit 3 Lesson 3.2 Principles of pH
Buffers
Chemical substances that neutralize acids or bases when added to a solution
Curriculum for Agricultural Science Education
Copyright 2011