What distinguishes blocky soil structure?

Blocky soil structure is characterized by aggregates that are irregularly shaped and resemble blocks. This structure is typically formed by the cohesive forces between soil particles and is most often seen in clay-rich soils. The key aspect that distinguishes blocky soil structure is that the horizontal and vertical dimensions of the aggregates are approximately equal, which allows them to fit together in a way that promotes stability and enhances porosity.

This equal dimensionality is important as it impacts the movement of air and water through the soil, as well as root penetration. The blocky structure facilitates drainage and aeration while also reducing compaction, making it conducive to healthy plant growth.

In contrast, options that describe horizontal extent being greater than vertical or aggregates consisting solely of fine particles do not accurately represent the nature of blocky soil structure. Similarly, the absence of a distinct shape implies a structure that is either loose or formless, which contradicts the well-defined nature of blocky aggregates. Hence, option describing equal dimensions provides the most accurate representation of blocky soil structure.