This prevents root burn and the buildup of soluble salts or excess fertilizer and reduces the chance of burning the plant. Back to Top Soluble Salts Reduced growth, brown leaf tips, dropping of lower leaves, small new growth, dead root tips, and wilting are all signs of high soluble salts. These salts will accumulate on top of the soil forming a yellow to white crust. A ring of salt deposits may be formed around the pot at the soil line or around the drainage hole. Salts will also build up on the outside of clay pots.
Soluble salts are minerals dissolved in water.
Fertilizer dissolved in water becomes a soluble salt. When water evaporates from the soil the minerals or salts stay behind. As the salts in the soil become more and more concentrated, plants find it harder and harder to take up water. If salts build up to an extremely high level, water can be taken out of the root tips causing them to die. High soluble salts damage the roots directly, and because the plant is weakened, it is more susceptible to attack from insects and diseases.