Which of the following is an observation when identifying soils?

• A. Whether man-placed fill or natural
• B. Soil pH
• C. Groundwater depth
• D. Root depth

Answer: (A)

Recognizing whether the material you’re looking at is man-placed fill or natural is essential because it tells you where the observed soil comes from. If it’s fill, the profile may not reflect native soil properties—textures can be uniform, horizons may be poorly developed or absent, and there can be abrupt contacts or debris that bias interpretation of drainage, compaction, and suitability for systems. This observation helps distinguish native soil from an introduced layer, which is key for accurate soil identification. The other items—pH, groundwater depth, and root depth—are important measurements or site conditions you assess, but they don’t by themselves identify the soil’s origin or horizon development in the way noting fill versus natural soil does.