There are two different types of soil, one which is acidic and the other is alkaline. And both types have different benefits for plants. The pH value of soil can be measured by a soil test kit.
There is a common misconception that Epsom salt and sulfur makes the soil acidic when in fact, it doesn't. However, this method has been used since the 16th century to help remove toxins from the soil so it's not recommended to use it for long periods of time.