CCA Irrigation Management and Water Use

Question 1

Which irrigation method typically achieves the highest application efficiency for row crops by delivering water directly to the root zone?

Accepted Answer

Drip/trickle irrigation

Answer

Drip/trickle irrigation delivers water directly to the root zone with minimal evaporation or runoff losses, typically achieving 90–95% application efficiency.

Question 2

Evapotranspiration (ET) as used in irrigation scheduling represents:

Accepted Answer

The combined water loss from soil evaporation and plant transpiration

Answer

ET combines water evaporated from the soil surface and water transpired by plants, and is the primary measure used to estimate crop water demand for scheduling irrigations.

Question 3

The crop coefficient (Kc) used in reference ET-based irrigation scheduling primarily accounts for:

Accepted Answer

Differences in water use between a reference crop and the actual crop at various growth stages

Answer

Kc adjusts reference ET (ETo) for a specific crop and growth stage, reflecting differences in canopy cover, root depth, and plant physiology compared to the reference (typically grass or alfalfa).

Question 4

Soil texture most directly affects irrigation scheduling because it determines:

Accepted Answer

Soil water-holding capacity and infiltration rate

Answer

Soil texture controls pore size distribution, which dictates how much plant-available water a soil can hold (field capacity minus wilting point) and how rapidly water moves through the profile.

Question 5

Which soil water content term represents the upper limit of plant-available water after drainage has ceased?

Accepted Answer

Field capacity

Answer

Field capacity is the water content remaining after gravitational drainage has essentially stopped (typically 1–3 days after wetting) and represents the upper limit of readily plant-available water.

(CCA) Certified Crop Advisor Practice Test

(CCA) Certified Crop Advisor Practice Test

CCA Irrigation Management and Water Use