Question

The comprehensive system of soil classification is based on

• A. Soil colour and vegetation
• B. Soil environmental factors
• C. Measurable soil properties
• D. Intrinsic properties of soil

Hint:

Soil classification focuses on quantifiable, objective soil properties.

Answer 1

The Correct Option is C

Comprehensive soil classification relies on measurable properties such as texture, structure, pH, conductivity, and horizon development, rather than appearance or subjective criteria.

Answer 2

Conceptual distinction:
Older, genetic systems of soil classification grouped soils largely by inferred formation factors, such as climate, parent material and vegetation, which are often subjective or not directly observed in the soil itself. In contrast, a comprehensive system, such as USDA Soil Taxonomy, was designed to be objective and quantitative, defining classes using measurable, diagnostic soil properties, for example horizon thickness, clay content, base saturation, and soil temperature or moisture regimes, that can be verified in the field or laboratory. Since the question asks what the comprehensive system is built on, rather than what influences soil formation, the basis is measurable soil properties rather than colour, vegetation or environmental factors, confirming option 3.