Last year I made raised beds to plant brassicas, but the soil is dense clay and I have a lot of runoff. As a result after the soil was piled up quite pleasantly, I got out the post-hole digger and made 12 holes 10 inches deep, spaced 1 foot apart, in each bed. Filled all the holes with compost then and planted the seedlings between and around the compost holes (3 rows of 7 seedlings each). I just fill up the holes to water - no runoff. My seedlings get the bottom watering they want, the worms enjoy it, and soon the soil will be much richer and nutritious.