What should be the focus when preparing the subgrade before top-soiling?

When preparing the subgrade before top-soiling, the focus should indeed be on facilitating bonding with the topsoil. This aspect is crucial because the effectiveness of topsoil in supporting vegetation and promoting growth depends significantly on how well it integrates with the underlying material. Proper bonding helps to ensure that water and nutrients are able to move efficiently between the topsoil and the subgrade, promoting a healthy environment for plant roots.

Creating a flat surface and ensuring compaction are important considerations in the preparation process but do not directly address the critical requirement for establishing a connection between the topsoil and the subgrade. While these factors can contribute to the overall stability and uniformity of the surface, they do not prioritize the interaction that will foster healthy plant growth.

Incorporating fertilizers, while beneficial for enriching the topsoil, is not the primary goal when focusing specifically on the subgrade preparation. The focus at this stage should be on enhancing compatibility and connection rather than adding nutrients, which come into play after the bonding has been successfully established.