i wouldnt use dog crap. but if you do use some sort of manure-cow,horse,rabbit it is best to compost it for a couple years. use it when it has the consistency of dirt. also bat and bird guanos work well and cost big$ but if you have cash to invest they are worth it. any good compost works well you can never get enough good compost its like gold. worm castings also a good additive. there are many natural things you can add search around.there are lots you can make or get for free if you have time to put some work into it.