The weather balloon represents a sand particle and the basketball represents silt particles. The glass beads represent clay particles. In reality, clay particles are plate-shaped. Texture is a basic physical property of soil that differentiates soils. A photomicrograph of a sandy soil is shown in Slide 12 .
Sand grains are angular in shape and tend to fit together rather closely in the natural state.
Large-sized pores exist between the grains, thus, the low water holding capacity and excessive drainage characteristics. As clay and organic matter contents increase, the physical characteristics of the soil change. Silt particles, because of their smaller diameter, impart greater water holding capacity and slower drainage, but do not contribute significantly to the fertility status of the soil other than through secondary effects. Silt particles are angular in shape and lack surface activity. Clay particles are very small in size, plate-shaped, and have surface activity.