Answer: If your landscapers spread native soil (which is alkaline and clayey), it may be that the roots of your grass are coming into contact with this soil and having a hard time penetrating. However, since you also added mulch, conditioner, and top soil, there may be several layers that are working against each other. The clay beneath all those soil amendments can become an effective moisture barrier if it dries out, and it can, even if you apply adequate water. I'm not sure exactly how to approach the problem. You may need to dig or rototill the area to mix the amendments and the native soil together, or you may be able to simply rent a core aerator and go over the entire lawn. A core aerator will remove one inch wide by three inch deep plugs from the soil. Spreading compost or sand over the lawn after aerating and then watering the area well will work the compost or sand into the holes made by the aerator, which will help loosen the soil, give the grass roots a place to grow into, and will also help hold moisture at the root area of the turf. There are no simple solutions to this dilemma!
Q&A Library Searching Tips