SeedS, Keep me posted on the results if you can. I am reasonably sure that we can add compost and organics with our machines, I just am not sure how well they will work during the actuall seeding process. One thing to consider is the amounts of organics everybody here seems to be recommending to use. They seem to be large amounts and a hydroseeder might not be the most efficient way to apply them. Mixing large amounts of meals in a slurry of water might make dough, ( I'm thinking cornbread). Compost on the other hand might be easier to apply and get spread evenly. You could even add seed for overseeding as you applied the compost.