Agronomy Irrigation and Water Management 1 — Questions and Answers
Question 1: Which irrigation method delivers water directly to the root zone and is the most water-efficient?
- Flood irrigation
- Center pivot irrigation
- Drip (trickle) irrigation (Correct answer)
- Furrow irrigation
Correct answer: Drip (trickle) irrigation
Drip irrigation delivers water slowly and directly to the plant root zone through emitters, minimizing evaporation and runoff losses.
Question 2: What is evapotranspiration (ET) used for in irrigation management?
- Measuring rainfall totals
- Estimating crop water use to schedule irrigation timing and amounts (Correct answer)
- Calculating herbicide dilution rates
- Predicting frost dates
Correct answer: Estimating crop water use to schedule irrigation timing and amounts
ET estimates the combined water loss from soil evaporation and plant transpiration, providing the basis for scheduling irrigation to replace crop water use.
Question 3: What is the field capacity of a soil?
- The minimum water content at which a plant can survive
- The soil water content after free drainage has ceased following saturation (Correct answer)
- The total pore space volume of the soil
- The maximum depth of water that can infiltrate in one hour
Correct answer: The soil water content after free drainage has ceased following saturation
Field capacity is the soil moisture content remaining after excess water has drained under gravity, representing the upper limit of plant-available water.
Question 4: Which of the following is a common method for measuring soil moisture in irrigated fields?
- Refractometer
- Tensiometer (Correct answer)
- Penetrometer
- Lysimeter
Correct answer: Tensiometer
Tensiometers measure soil water tension (suction), which indicates how tightly water is held in the soil and when irrigation is needed.
Question 5: What is the permanent wilting point (PWP) of a soil?
- The soil water content at which irrigation must begin
- The soil water content below which plants cannot recover turgor (Correct answer)
- The optimal irrigation frequency for sandy soils
- The maximum root depth for most field crops
Correct answer: The soil water content below which plants cannot recover turgor
The permanent wilting point is the soil moisture level at which plants can no longer extract water and will not recover even when water is added.
Question 6: Center pivot irrigation systems are designed to apply water in what pattern?
- Rectangular grid
- Circular pattern around a central pivot point (Correct answer)
- Uniform grid using overhead sprinklers
- Linear strips along field contours
Correct answer: Circular pattern around a central pivot point
Center pivots rotate around a fixed central point, applying water in a circular pattern and covering large areas efficiently.
Agronomy Irrigation and Water Management 1
Which irrigation method delivers water directly to the root zone and is the most water-efficient?