Which hydrological soil group has the highest infiltration rate?

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

Answer: (D)

Water moves into soil most quickly when the soil has large, well-connected pores. Coarse-textured soils, like sand, have bigger voids and less resistance to water flow, so infiltration occurs rapidly. Clay has very tiny pore spaces and strong particle cohesion, which slows infiltration and encourages runoff. Silt is finer than sand but coarser than clay, so its infiltration rate is intermediate. Loamy sand mixes in finer particles, which can reduce infiltration somewhat compared to pure sand, but it still infiltrates faster than silty or clayey soils. Among these options, the sand texture has the coarsest structure, leading to the fastest infiltration.