What is meant by plastic soil?

Plastic soil refers to soil that can be molded and retains shape, particularly when it is moist. This characteristic is crucial in understanding how certain types of soil behave under various conditions, especially in construction and landscaping applications.

When soil is described as plastic, it implies that it can undergo deformation without breaking or crumbling, which is typically due to the presence of clay particles. These particles have the ability to absorb water and swell, allowing the soil to be shaped into different forms when wet and to maintain those forms as it dries. This property is often tested in geotechnical engineering through the criteria of plasticity, which helps determine its suitability for various projects.

The other choices do not accurately describe the fundamental aspect of plastic soil. Erodible soil pertains to how easily soil is washed away or displaced but does not refer to the ability to retain shape. Soil with high organic content may contribute to fertility but does not inherently possess plasticity. Compacted and hard soil may suggest stability and structural integrity but lacks the malleable qualities associated with plasticity.