In RUSLE, the A factor is expressed as what units?

• A. Inches of rainfall per year
• B. Cubic meters per hectare per year
• C. Pounds per square foot per year
• D. Tons per acre per year

Answer: (D)

The A factor represents the average mass of soil lost per unit area each year. Because it’s a rate of soil erosion over time and per area, the units are mass per area per time. In U.S. customary units, that is tons per acre per year (and in metric units, Mg per hectare per year). The other options describe rainfall, volume, or nonstandard mass-per-area rates, which do not capture the annual soil loss per area that A quantifies.