After a year, the tomb became smaller and shorter because of the wind and rain. Adding soil is to restore the tomb to its original state and is a comfort to the dead. Others also know that this family has a future!
There is a hole in the grave, which can be blocked by filling it with soil, but don't use stone and cement as the grave, which is really blocking the pores and bad feng shui. Filling graves and blocking holes has no effect on feng shui.