What does Plasticity in soil refer to?

Plasticity in soil refers to the degree of soil deformation without breaking. This characteristic indicates how malleable or workable the soil is when subjected to stress, such as compaction or shaping. Soils with high plasticity can be molded and will retain their shape until subjected to further forces, while soils with low plasticity may crumble or fracture when stressed. Understanding plasticity is crucial in septic system design as it impacts the soil's ability to handle applied loads, water flow, and the overall stability of the system.

The other options relate to different soil properties. For instance, the ability of soil to support heavy structures pertains to soil bearing capacity, which focuses on strength rather than plasticity. Moisture retention capacity involves how well soil can hold water, which is important for drainage and irrigation but does not directly define its plastic characteristics. Lastly, organic content affects soil fertility and structure but does not define the soil's plastic behavior.