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 color and temperature

Answer

Soil pH and nutrient content

Answer

Soil biological activity

Question 2

Soil compaction reduces water infiltration primarily because it:

Accepted Answer

Crushes aggregates and reduces pore space between particles

Answer

Increases soil temperature significantly

Answer

Lowers soil pH below plant tolerance

Answer

Increases organic matter decomposition rate

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

Higher operating pressure

Answer

Larger sprinkler heads with higher precipitation rates

Answer

Longer single run times

Question 4

Organic matter improves soil water retention primarily by:

Accepted Answer

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

Answer

Increasing soil salinity and conductivity

Answer

Raising soil pH to optimal levels

Answer

Reducing microbial activity in the root zone

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

Clay soil — approximately 0.1 to 0.2 inches PAW per foot

Answer

Loam soil — approximately 3.5 to 4.0 inches PAW per foot

Answer

Sandy loam — approximately 3.0 to 3.5 inches PAW per foot

Question 6

The primary purpose of performing a ring infiltrometer test before designing an irrigation system is to:

Accepted Answer

Establish the maximum application rate to match when selecting sprinkler heads

Answer

Determine the soil's nutrient and pH profile

Answer

Measure the maximum depth of irrigation water needed per cycle

Answer

Calculate flow velocity requirements for the main supply line

Question 7

High soil salinity harms turfgrass primarily because:

Accepted Answer

Dissolved salts draw water out of plant roots through osmosis, causing drought-like stress

Answer

It causes soil to freeze at higher temperatures

Answer

Salt blocks sunlight from reaching the root zone

Answer

Salt prevents nitrogen uptake by soil bacteria