Personally, I would just get some fresh manure (from the winter's months) and make compost tea. It's what I do every winter. My husband hauls cattle, I get enough from the winter hauls to get through spring, summer, fall and winter. I only use winter manure because I don't have to worry about grass seed or any other seed going into my ground from someone else's pasture. Just from reading what you are doing, this sounds more like what you want. It's instant, it soaks into the ground so the soil and plants can benefit and it doesn't kill anything.