Because of this, it often performs better than many other deicing salts, especially at lower temperatures. Some highway departments spray liquid calcium chloride over rock salt to lower its melting temperature. Sodium chloride Rock salt first was used as a road deicer in the 1940s. An estimated 10 to 14 million tons will be used yearly on roads in the United States and Canada. Sodium chloride is relatively inexpensive, but it can burn plants and corrode metal and concrete.
Sodium chloride is the salt most commonly used to season food.
Urea Synthesized from ammonia and carbon dioxide, urea is used primarily as a fertilizer. It has a lower burn potential than potassium chloride, and is a source of nitrogen fertilizer. Adjacent turf may green and grow excessively in the spring. If urea remains on top of the soil, it rapidly breaks down to ammonia, which escapes into the air. This is a new salt-free melting agent.