Last year when I built my raised beds, I lined the bottom with newspaper, then a couple inches of lawn clippings and then top soil. This year when I roto tilled, there was no remains of the grass or news paper. For my large beds, I am mixing in a 2.2 c/ft bale of peat and 6 40lb bags of compost/manure. I moved some of the original topsoil into the new beds I build and mixed in compost/maure/peat into them also. It rained good and hard today, the mix settled like I had hoped. I might mix it up once more before planting, dont know yet...
Total I have/have used 4 2.2 cu/ft bales of peat and 23 40 lb bags of compost/manure. LOL Damn rain, go away, Matt wants to play!