Which soil generally has the highest hydraulic conductivity?

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

Answer: (C)

Hydraulic conductivity reflects how easily water can move through a soil, and it climbs with larger, well-connected pore spaces. Sand has relatively large grains that leave wide, interconnected pores, so water can flow through with little resistance. Clay, in contrast, is made of very fine particles that expand and create tiny, tortuous pores, trapping water and hindering flow, so conductivity is low. Silts are intermediate in grain size and pore structure, giving moderate conductivity. Peat can be highly porous but often has a more irregular, discontinuous pore network due to its organic matter, which can limit continuous flow paths. So, the soil with the highest hydraulic conductivity is sand.