Most shrubs send up suckers, or fresh shoots, when they’re stressed or damaged. The new growth provides energy and nutrients so the shrub can survive bad weather years or other crisis conditions. This ability makes removing unwanted shrubs hard because efforts to cut them down can lead to more undesirable shrubs. Rather than using chemical herbicides, rock salt can kill shrubs, but it will also make the soil sterile.
Death by Starvation
Once in the soil, rock salt replaces nutrients like potassium, calcium, potassium and magnesium, preventing the roots from absorbing needed minerals. Once these chemicals are replaced, the tree’s roots absorb the salt, together with water, rather than nutrients. Inside the plant, the salt interferes with the shrub’s ability to make carbohydrates and sugars through photosynthesis. The tree will starve to death. Rock salt kills all plants in exactly the same manner. Thus, anything else in the region you treat will die.
Death by Dehydration
Rock salt also kills by creating water inaccessible to the plant. Where the roots come in contact with the rock salt, it will also pull moisture from the roots. Inside the plant, the salt draws moisture from the plant cells, leaving the tree dehydrated. The shortage of water dries out the tree, therefore it dies.
Death to the Neighbors
Any plant that comes into contact with the stone dies the identical manner. Flowers, trees and grass near the stone salt application region could be killed. Rock salt doesn’t remain where it is implemented, either. Water will dissolve and spread the stone farther into the ground, bringing it into contact with more plants and causing more harm.
Death Over Time
Removing rock salt from the ground is so tough that ancient armies used it to destroy the plants of enemies. It will leach from the soil finally. Water from rain or watering slowly dissolves the salt and draws it deeper in the soil, a little at a time, taking it under the level where roots develop. This method takes years, and until the salt is eliminated, plants will not grow. The salt can also end up in the water table in streams and ponds, which isn’t good for water quality or wildlife.