The make-up of soil according to proportion of sand, silt and clay is known as

Correct option is A

The correct answer is (A) Soil texture

Explanation:
• Soil texture refers to the relative proportions of the various sizes of individual mineral particles in a soil.
• Specifically, it is the percentage of Sand (0.05 - 2.0 mm), Silt (0.002 - 0.05 mm), and Clay (less than 0.002 mm).
• Texture is considered a "basic property" of soil because it does not change easily with farming practices (it is permanent).
• It determines many other soil characteristics, including water-holding capacity, nutrient retention, and drainage.

Information Booster:
• The USDA Soil Texture Triangle is used to classify soils into 12 textural classes based on these proportions.
• Textural analysis is usually performed in the lab using the Hydrometer method or Pipette method, based on Stokes' Law.
• In the field, texture is often estimated using the "feel method" (rubbing moist soil between fingers).

Additional Knowledge:
• Soil structure (Option B): Refers to the arrangement of these individual particles into groups or aggregates (peds).
• Soil horizon (Option C): A distinct layer of soil parallel to the surface with characteristics different from the layers above and below.
• Soil health (Option D): A holistic term for the continued capacity of soil to function as a vital living ecosystem.