In the United States, people often use large amounts of salt to remove dangerous ice from roads and walkways in the winter. But when the spring arrives, all that salt can really damage plants in the garden. Salt is the chemical sodium chloride.

Salt pulls water from living cells, like plant roots and the healthy ground soil around them. So, spring growth may show up lighter in color than normal, or, in the worst cases, plants may simply die. Rain can wash away much of the salt, permitting some older plants to live. Salt can also be removed by pouring a large amount of water on the ground where plants are growing. But the best action is to simply use less salt.

There are. of course, other things that can be used to cover for sodium chloride. One is the chemical calcium chloride, which does less damage to plants and melts ice faster than salt. It also works when the temperature is below negative 17 degrees Celsius. Salt loses some of its effectiveness at temperatures below negative 12 degrees.

Still, calcium chloride does put chloride ion（氯离子）, which plants don＇t like, into the soil. It is also more expensive and can do more damage to cars. Calcium magnesium acetate, also called CMA, has become a popular alternative. It is made by combining limestone, a type of rock. and vinegar. It breaks down naturally so it does not damage plants or soil. It stays on roads and does not hurt cars.

CMA does have problems, however. It is most effective at around negative 9 Celsius, just like salt. And it is better at stopping ice from forming rather than removing it. So, it is best placed on a road before the temperature gets very cold. Some materials other than salt-such as sand or very small pieces of wood- can also work against ice. But they can be very messy.