Loam is best described as what?

• A. All sand
• B. Predominantly clay
• C. An optimum mix of particle sizes with about 40% sand, 40% silt, 20% clay
• D. Very high gravel content

Answer: (C)

Loam describes a soil texture that balances the three main particle sizes—sand, silt, and clay—to give good drainage, aeration, and nutrient-holding capacity. The best loam has roughly equal parts sand and silt with a smaller amount of clay, around 20%. This mix maintains structural stability and porosity: sand provides drainage and airflow, silt increases water-holding capacity, and clay helps retain nutrients and supports aggregation. Together they create a soil that’s easy to work, drains well enough to prevent waterlogged roots, yet holds enough moisture and nutrients for plants.

If a soil were mostly sand, it would drain too quickly and hold little water or nutrients. If it were predominantly clay, it would compact easily, drain poorly, and limit root growth. A very high gravel content would be too coarse to retain water or nutrients. So the description of an optimum mix with about 40% sand, 40% silt, and 20% clay best captures what loam is.