Final answer:
Soil sampling involves manual testing for assessing soil quality, texture, and structure, useful for historical knowledge areas and geotechnical engineering designs.
Explanation:
Manual test in soil sampling refers to the process where individuals assess the soil texture, structure, and overall quality using tools like spades and rulers relying on human sight and touch.
This visual method can be used to assess soil structure changes over time in areas with historical knowledge, grouping similar soils and topography for testing.
It is a practical application technique in geotechnical engineering, providing insights into soil strength for construction designs like foundations, retaining walls, and slopes.
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