To add soil amendments, such as compost or fertilizers around a plant, on top of the soil.

Layering levels of a lawn to maintain one steady level and improve general quality of both soil and grass

 To spread manure or fertilizer on the surface of (land) without working it into the soil. I top-dress my garden beds every year with fresh leaf mold.

Top-dress means to spread a thin layer of compost over soil without digging it in, allowing the slow release of nutrients into the soil.