Grab a worldspace coordinate node, mask out the R and G values. Divide that by the tile size of the texture (Around 1024 or 512 is usually good). Use that for the UVs of your texture maps that you plug in to your grass and the terrain. Should work.
World position -> component mask (R+G) -> Divide by a number depending on how large the noise texture is -> plug in to the UVs of your noise texture. http://i.imgur.com/lOY8s.png Then just multiply your normal diffuse with the noise texture. Or just use the noise tex as the diffuse.