How does surface area affect water-holding capacity ?
• Explain why water stays in some soils longer. The amount of water adhering to the surface of soil particles increases with the surface area of the particles. Smaller particles, such as clay, have a much larger surface area per weight than larger particles, such as sand, and have a proportionately larger amount of water clinging to them. There amount of space between particles does not depend on the size of the particles, but the pores size 1 does depend on particles size. Capillary forces 3 (adhesion + cohesion) hold water more strongly against the pull of gravity, meaning the water-holding capacity 1 is larger in fine-textured soils.
