The longest ribbon length in a moist soil indicates higher clay content.

• A. Clay
• B. Sand
• C. Silt
• D. Humus

Answer: (A)

The test measures plasticity and cohesion from fine mineral particles. In moist conditions, clay minerals are very small and plate-like, so they bind together into a sticky film that can be stretched into a ribbon. The more clay present, the longer the ribbon you can form before it breaks, because there’s more cohesive material to hold the ribbon together. Sand is coarse and crumbles, giving little to no ribbon. Silt can make a short ribbon, but not as long as clay, since its particles are larger and less cohesive. Humus adds organic stickiness, but the ribbon length mainly reflects clay content rather than organic matter. So, the longest ribbon indicates higher clay content.