Golf balls are made of a variety of materials, including rubber, synthetic rubber, urethane, and Surlyn. Most golf balls have a solid core surrounded by one or more layers of wound filaments. The cover is the outer layer of the ball and is typically made of harder material to protect the inner layers and provide durability. Golf balls are designed to withstand repeated impact and wear; however, they will eventually show signs of wear and tear. Depending on the materials used, golf balls can take anywhere from a few months to several years to decompose.
The majority of golf balls are composed of materials that do not readily decompose in the environment. For example, rubber does not break down easily and can persist in the environment for years. Similarly, synthetic rubbers and urethanes are also resistant to degradation. The only part of a golf ball that will decompose relatively quickly is the inner core made of wound filaments. However, even this will take several months to break down completely.
In general, it takes quite a long time for golf balls to decompose fully. If you're looking to get rid of old golf balls, your best bet is to recycle them rather than throwing them away in the trash.