Sandy soil is soil comprised of particles that are larger than 0.05 millimeters and smaller than 2 millimeters. Sandy soil retains little water and aerates well because of the large size of its particles.
Soil is divided into three different classifications based on the size of the particles in it. In general, the smaller the particles, the more tightly it packs and the more water it retains. Sandy soil is comprised of the largest particles. Silt is defined as soil with particles ranging in size from 0.002 millimeters to 0.05 millimeters. Clay is anything with a particle size of less than 0.002 millimeters.