I am building a hugelkultur bed in Minnesota in a student garden. We're using it as a demonstration for our community, so I want to make sure it is a good example!
We have access to plenty of wood and plant material but not to compost. We had a new garden area tilled this spring and have weeded out 4 wheelbarrow loads of large chunks of sod that are about 1/2 soil and 1/2 plant material. Our soil has 9% soil organic matter.
Can we use the sod to fill in around the logs instead of using compost? If yes, I'm assuming adding a bucket or two of compost would still be a good idea to jumpstart the microbial community in the bed?
Just make sure your sod is free of Quack Grass. I used a little uncomposted sod in my hugel bed, and quackgrass keeps coming up from a few rhizomes in the sod. i pick as much as I can, roots and all, and still it comes back. If in doubt, put a black material like plastic over the sod and in the sun to bake all the roots. Enjoy your garden!