Soil Science and Plant Water Requirements Flashcards

Which soil type has the highest water-holding capacity?

Answer: Clay soil

Clay soil has the smallest particle size and greatest surface area, allowing it to retain more water than coarser-textured soils.

Field capacity is defined as the soil moisture level that remains after:

Answer: Excess water has drained away by gravity

Field capacity is the water content remaining in soil 24–48 hours after saturation, once gravitational drainage has stopped.

The permanent wilting point is the soil moisture level at which:

Answer: Plants can no longer extract water and wilt permanently

At the permanent wilting point, remaining soil water is held too tightly by soil particles for plant roots to extract it, causing irreversible wilting.

Which of the following best describes evapotranspiration (ET)?

Answer: The combined loss of water through soil evaporation and plant transpiration

ET represents total landscape water demand by combining direct evaporation from soil and transpiration through plant leaves.

Plant Available Water (PAW) is correctly calculated as:

Answer: Field capacity minus permanent wilting point

PAW is the range of soil moisture between field capacity and permanent wilting point that plant roots can actually extract and use.

Sandy soils typically have infiltration rates closest to which range?

Answer: 1.5 to 3.0 inches per hour

Sandy soils have large pore spaces that allow rapid water infiltration, typically at rates of 1.5 to 3.0 inches per hour.

Which soil texture is most recommended for turfgrass because it balances drainage and moisture retention?

Answer: Sandy loam

Sandy loam provides adequate drainage to prevent waterlogging while retaining enough moisture and nutrients to support healthy turfgrass growth.