Soil Science & Amendments Flashcards

Which soil texture has the highest water-holding capacity per unit volume?

Answer: Clay

Clay has the smallest particles, the greatest surface area, and the smallest pore spaces, allowing it to retain the most water per unit volume.

On a soil penetrometer, readings consistently above 300 psi typically indicate:

Answer: Severe compaction that significantly restricts root growth

Penetrometer readings above 300 psi signal severe compaction that physically prevents root penetration and reduces turfgrass vigor.

Calcitic limestone is applied to sports field soils primarily to:

Answer: Raise soil pH by neutralizing acidity

Calcitic limestone (calcium carbonate) reacts with hydrogen ions in acidic soils to raise pH toward the optimal range for turfgrass.

According to USGA green construction specifications, approximately what percentage of the root zone mix is sand?

Answer: 80–100%

USGA-specification root zones are predominantly sand (80–100%) with a small peat fraction to achieve the required infiltration rates of at least 6 inches per hour.

Which amendment improves both drainage AND cation exchange capacity in sports field soils?

Answer: Calcined clay (e.g., Turface)

Calcined clay products like Turface have a highly porous structure that improves drainage and also possess elevated CEC for nutrient retention.

What is the primary concern with incorporating excessive organic matter into a sports field root zone?

Answer: It decomposes over time, leading to settling and reduced drainage

As organic matter decomposes, pore space decreases, the mix settles, and drainage capacity declines — often within a few years of construction.

What does soil bulk density measure?

Answer: The mass of dry soil per unit of total volume, including pore spaces

Bulk density is mass of oven-dry soil divided by total soil volume (solids + pores), and is a key indicator of compaction and porosity.