I think horse manure would be good. I climbed over the fence next to me and got some cow manure and soaked it in water that i watered my tomatoes with . I had the best tomatoes I have ever had.. I do not plan on using comerical fertilizer this year.Go organic....Also my city where I live, gathers up all the leaves from the neiborhood and carries it where it is made into mulch. and you can drive your truck over and they load it for you. It is so rich and dark..