Why shouldn't you mix topsoil and mulch?

Mixing topsoil and mulch can hinder the growth of plants because the mulch can create a barrier that prevents water and nutrients from reaching the soil. Additionally, mulch may decompose at different rates than topsoil, leading to uneven soil quality and structure over time. It’s generally more effective to use mulch as a surface cover to retain moisture and suppress weeds, rather than mixing it into the soil. Keeping them separate allows each to fulfill its role effectively.