Will throwing grass clippings on a steep dirt hill help prevent erosion?
It wouldn’t stop serious erosion, but if you have the grass clippings anyway, it can’t hurt. I think would be best if you laid in strip across the hillside (not up and down). Then if it stays in place, you’d have a little ridge. You could plant things uphill from the ridge and they’d have better chance of taking root. My house is on top of hill and when I plant something on the hill, I put something below it – rocks, mulch, leaves, sticking sticks into the ground – something to make a little level area to catch water for the plant. If you want to seed it, wildflower seed would be more attractive than grass.