IrrigationUnit 1.5 | 5
Instructor’s Lecture Outline
Lecture Outline: Irrigation
for the instructor
A. Pre-Assessment Questions
- How do you determine when it is time to irrigate, and how frequently?
- How do you determine how much water to apply?
- What are some of the environmental factors that may influence the frequency or duration of irrigation?
- What are some of the environmental factors that may influence the type of irrigation used?
B. The Role of Irrigation Water in Agricultural Systems
- Sustains soil biological and chemical activity, extending mineralization and plant
growth during dry periods - Creates soil solution for nutrient uptake and transfer
- Provides necessary building blocks for the formation of carbohydrates
- Provides physical support/structure for plant
- Maintains optimal temperatures within the plant
- Protects crops, e.g., during threats of freezing temperatures
C. Water Cycling in Agricultural Systems
- Definition of terms
a) Transpiration
b) Capillary action
c) Evaporation
d) Evapotranspiration (ET)
e) Evapotranspiration rate (ETo)
f) Infiltration
g) Percolation
D. Units of Water Measurement
- Definition of terms
a) Acre inch
b) Acre foot
c) Gallons per minute (GPM)
E. Soil Moisture, Plant Stress, and Crop Productivity
- Reduction of yield due to water stress
a) Water-stress-sensitive stages of crop development (prioritized)
• Flowering
• Yield formation/fruit set
• Early vegetative growth/seedling stage
• Fruit ripening
- Water stress and an increased susceptibility to pests and pathogens
- Permanent wilting point and crop loss