CIT Soil Science and Plant Water Requirements 3

Question 1

Which soil characteristic most directly controls the rate of water infiltration?

Accepted Answer

Soil texture and structure

Answer

Soil texture (particle size) and structure (arrangement of particles into aggregates) determine pore size and connectivity, which directly govern infiltration rate.

Question 2

Soil compaction reduces water infiltration primarily because it:

Accepted Answer

Crushes aggregates and reduces pore space between particles

Answer

Compaction collapses soil aggregates and reduces the volume and connectivity of pore spaces, leaving fewer pathways for water to infiltrate.

Question 3

To prevent runoff on low-infiltration clay soil, an irrigation technician should program the controller to use:

Accepted Answer

A cycle-and-soak strategy

Answer

Cycle-and-soak applies water in multiple short cycles with rest intervals, allowing slow-draining clay soil to absorb water between cycles before runoff occurs.

Question 4

Organic matter improves soil water retention primarily by:

Accepted Answer

Binding soil particles into aggregates and increasing water-holding pore space

Answer

Organic matter improves soil structure by cementing particles into aggregates, creating more stable pore space and significantly increasing plant-available water holding capacity.

Question 5

Which pairing correctly matches a soil texture with its approximate plant available water (PAW) per foot of depth?

Accepted Answer

Sandy soil — approximately 0.5 to 1.0 inches PAW per foot

Answer

Sandy soils hold approximately 0.5 to 1.0 inches of plant available water per foot because their large pores drain quickly, leaving relatively little tightly held water.

CIT - Certified Irrigation Technician Practice Test

CIT - Certified Irrigation Technician Practice Test

CIT Soil Science and Plant Water Requirements 3