Soil suitability class is primarily determined by which factor?

• A. Depth of limiting zone
• B. Soil color
• C. Soil fertility
• D. Moisture content

Answer: (A)

The main idea is that how deep the restrictive layer is determines soil suitability class. If a hardpan, dense clay, or bedrock sits close to the surface, roots can't penetrate, water movement and aeration are limited, and the land’s use options are strongly constrained—that lowers the suitability class regardless of other properties. In contrast, a deeper, nonrestrictive root zone means the soil can support more demanding uses, with fertility and moisture conditions then shaping the final classification.

Soil color, fertility, and moisture content matter for productivity and management, but they don’t set the primary limit as strongly as the depth to the restricting layer does.