Lawn surface relief and slopes. The surface of the lawn should be as flat as possible. Slight undulations are allowed only on very large surfaces. The slope of the surface is often the result of the natural topography, however, you should not maintain a too steep slope, because they can make it difficult, and even prevent the mower from moving. On steep slopes, soil flushing may occur during sudden rainfall. This is especially dangerous on heavy soils, impermeable in the initial period of lawn growth (after its wearing). Therefore, the slope of 15%. On the other hand, slight slopes of the lawn surface, amounting to approx 3-5%, may be desirable for surface drainage.
Maintaining such slopes is even necessary on heavy and impermeable soils.
When shaping the soil surface for the lawn, you should avoid leaving hollow concavities. Lingering water on the surface of the lawn, especially during spring thaws, may cause air access and plant dieback. Maintaining surface slopes is not necessary on sufficiently permeable soils or on impervious soils, with adequate drainage.