Rock Salt Damage to Soil & Lawns

Rock Salt

• Rock salt is a common form of deicer and made from the mineral halide. Chemically, rock salt is identical to table salt, however, it is coarsely ground, resembling fine gravel. In sufficient quantities, rock salt will damage or kill the plants in your lawn. The extent of this damage is dependent on the concentration of salt in the soil and the tolerance level of your plants. Species adapted for marshes or coastal areas typically grow well in soils with a high salinity.

Plant Damage

• Rock salt prevents plants from utilizing the water in the soil, causing them to wilt. High salinity levels causes evergreen trees to die off and results in discolored or burnt-looking leaves in deciduous plants. As rock salt breaks down in the soil, it releases chloride that accumulates in the leaves of plants, resulting in leaf scorch at toxic levels. These problems will detract from the aesthetics of your lawn plants and weaken them, making them more susceptible to disease and other issues.

Mitigating Damage

• Rock salt is a relatively difficult chemical to remove from the soil. Tilling powdered gypsum into the soil can help decrease the damage to your plants but will not lower the amount of salt in the soil. The only effective way to reduce the salinity of your soil is to physically remove the salt. Using leaching, you can steadily decrease the concentration of salt to a safe level. This process uses large quantities of water to flush the salt from the soil and disperse it. If you decide to leach the soil, keep in mind where the runoff will go, since it will carry the salt in that direction. In small areas, you can simply replace the soil in the affected area.

Preventing Damage

• The most effective way to prevent damage to your lawn from rock salt is to control how it is used. Avoid using rock salt whenever possible and only apply it in thin layers as needed. Using warm water to disperse ice in conjunction with rock salt will decrease the amount of rock salt you use and help prevent it from concentrating in one area. Avoid applying rock salt to sidewalks or driveways near areas where sensitive plants will grow later in the year.