We use it when talking about how we sort things into groups according to their properties, such as acidic, alkaline or neutral. The pH of a substance can be tested if it is an aqueous solution.

"Maintaining a neutral pH level is optimal for microbial activity ... "However there are some things to know." Among them: Here are two DIY solutions for testing soil pH without a kit.

When talking about how to plant and how to grow plants in the garden, one of the things that ... ‘The pH scale goes from zero up to fourteen, with pH seven being the neutral point.’ ...