2 years ago I sowed my yard with Zenith Zoysia grass seed (not sod). It rained tremendously every other day and washed ruts in my yard. It has always been my intention to plow it up and start over with fescue (that's what I'm familiar with), but now the Zoysia is looking pretty good. Here's the question: Can I fill in the ruts a little at a time, allowing the Zoysia to grow through the new soil everytime before I add more until the ruts are level? If I can, what is the best to fill in with (top soil, sand, etc.) For reference, I have extremely compacted clay where I live. How deeply can I bury the Zoysia without killing it, if I keep it watered?