So I put some sod down, and I really dug into the ground before I did because it was really bad soil on top. Anyway, I raked it and all, but it was hardly even. The sod has taken root now, but the ground below it has some rather large holes from my poor job. What can I do to the ground in its current state to fix it? And what can I do in the future when I lay sod down, just lightly rake the top?