Soil quality is one of the most important factors in lawn growth. When establishing a new lawn, it is recommended to have a minimum thickness of 15 cm of quality topsoil to provide an optimal growing environment for the roots. However, when the lawn is already established and the soil is not ideal, as is the case in many regions of Quebec where the soils are clayey (“loamy”), can we still have a beautiful lawn? Of course you can!
Clay soil, advantages and disadvantages :
Clay soils have the characteristic of holding a lot of water and nutrients. This can be an advantage for the lawn in some circumstances, but clay also causes other problems. For example, the soil will take longer to dry out after a rain, and will be more prone to compaction from foot traffic or equipment. Conversely, when the soil is dry, it becomes very hard and may even crack in places.
How do we know if our soil is clay?
To determine if our soil is clayey, we can use an easy test called the “pudding test”. We take a small amount of wet soil in our hand, and try to form a ribbon by rubbing it between our two hands (a bit like children making play dough). The longer the ribbon, the more clay-like the soil.
How to improve clay soil?
To improve clay soils, regular aeration followed by topdressing is needed to improve the soil. One might be tempted to think that adding sand will lighten the clay and improve drainage and aeration. However, the opposite is true: adding sand to the clay will cement the soil and make it even harder. Instead, it is recommended that organic matter, in the form of compost, be added to lighten the soil and improve its structure.
However, this process must be repeated for several years before the effects are seen, as only a small amount of soil can be changed each time. Other cultural practices can be implemented to improve soil quality:
Leaving mowing residue in place (grasscycling). These residues contribute to the addition of organic matter in the soil and stimulate microbial life. Note that this practice is recommended for all types of soils, not just clay soils;
Fertilize the soil properly. Fertilization (natural or mineral) contributes to the growth of the lawn and thus to the production of organic matter by the lawn (leaves, stems and roots that will decompose). It also stimulates microbial life;
Water before the soil becomes too dry. It is better to water occasionally in depth than frequently on the surface;
Avoid driving on the lawn or mowing it when it is soaking wet to reduce compaction.
With these tips and a little patience, your lawn will become more beautiful and your soil will be healthier.