I have a (mostly) dirt and weeds backyard to which I am planning to add sprinkling and new sod next month. However, my locality requires (and I agree since the soil is poor) that I rototill in compost to prepare the soil before sod is installed. My backyard is also uneven and bumpy. Thus, would it be better to rototill/flatten the yard before or after I begin digging the trenches and laying pipe? Is there any other prep I should do before installing sprinkling?
When I install a sprinkler system, I Rototill first, then trench and install the piping, etc. then backfill trenches, compact the trenches, then flatten/roll the yard in prep for hydro-seeding or sod. You'll want to be sure to compact the backfill in the trenches or the dirt will settle over time and you'll be able to see/feel the depressions where the trenches are.