Understanding these characteristics of soil helps the gardener amend soil. Urban soil is often quite different from the native soil. The native soil may have been compacted by heavy equipment and traffic. Subsoil excavated from basements is often dumped on the surface. Soil texture affects the water-holding capacity of soil, movement of water through the soil and ease of cultivation.
Sand is visible, silt particles are the size of talc and clay particles are microscopic.
Soils that are coarsely textured are sandy. Medium-textured soils have equal parts sand, silt and clay. Finely textured soils are mostly clay or clay and silt. The same weight of clay can hold 50 times as much water as very fine sand particles. Soils containing a high percentage of clay are undesirable because the small particles pack tightly together, leaving little pore space for air and available water.