I haven't grown in "soil" in ages. But I do start all my hemp in pro-mix and transplant to outdoors. The thing is our "soil" in Colorado is more like sand with some clay and some other matter.. But mostly sand. So that being said, for me, it's sort of like soilless growing media, like pro-mix. I have found it's easier to maintain the plants, though. I primarily use dried cow patties that are all over around my ranch, break them down in buckets of water and use that to feed plants. Only have to "feed" them a couple times a season this way, just keeping up on watering and what little nutrients are in the sand, the plants actually do quite well.
I also do compost piles to make teas for feeding, usually around flowering time. You can also make a kelp tea if you find freeze dried kelp (can be found at Asian/Pacific markets pretty easily). I don't know if it's as good as making a live kelp tea, but I've bought a few packages of kelp and added it to my 400 gallon tanks, let it sit for a couple of months, and use to feed during flower. Works pretty well for me. There are all sorts of things you can do to grow organic. If you dig around here on the Farm forums you'll probably find a couple good threads that cover making organic soil amendments.
