I have wrestled with this question for a while. I make my own garden soil mix which is made from a soil base, aged horse and chicken manure, aged grass clipping, saw dust and very aged mulch all mixed in. My vegetables seem to be growing well but I wonder if I should water with a weak liquid fertilizer once every so often or if this have a detrimental effect on the plants. I would appreciate your views to steer me in the right direction.