The main reasons for top dressing are:

• Create a level surface: If you have a lawn with minor undulations and dips, regular applications of top dressing will gradually level the lawn up by filling the hollows.
• Improve the drainage: This task will improve the drainage on a lawn especially after aeration has been carried out. If you have a heavy poor draining soil i.e. clay, using a higher sand percentage top dressing will improve the drainage from the surface of the lawn. We you would use a peat/loam based top dressing on a high sand soil lawn if it had a problem with leaching. Peat and loam have greater water retention properties than sand, therefore they would improve the drought resistance of your lawn is it is of a high sand content build up.
• Thatch breakdown: A good top dressing program can help with the decomposition of thatch. Regular applications of top dressing help reduce the thatch layer and encourages natural breakdown.
• Helps encourage a thicker lawn: It encourages the grass to produce new shoots resulting in a thicker, tight knit sward; therefore reducing the invasion of weeds and moss.