A soil having pH 6.0 is called

A soil having a pH of 6.0 is called Acidic soil. As the pH level below 7 is categorized as acidic soil whereas the pH of the soil above 7 - 14 is categorized as basic soil.
The use of fertilizers, especially those supplying nitrogen usually causes acidity in the soil. And most plants thrive in slightly acidic soil because that pH affords them good access to all nutrients.