How do i customize the settings in 2 different surfaces

Hi guys,

i m pretty new to unity and was wondering if i can get some help from here. I am working on a project where i need to 2 types of surfaces on the same terrain and each of these 2 types of surfaces have different physics reactions, for e.g. a ball bouncing on a grass compared to a ball bouncing on a dirt surface, i was wondering on how i can bring these 2 textures over the same terrain and give them separate physics reactions. The problem is when i place one surface over the other the character seems to float and the reaction is not great. It will be great if someone could help me out here.