First sticking a finger in only tell you how wet it is as far as your finger goes. Try to learn to lift the pot and feel for dryness in the weight it helps. I veg in 20-20-20 nutrients to make my plants happy your chicken poo might not have the right N value is all. I was looking at a fertilizer today, had 2.8-1.4-.5 now that is nowhere near any good on its own, I would have to add up to 17.2 of other ferts to get to my 20. You need to figure out what the chicken poop values are to know for sure, checking ppm runoff is a good way to tell where your at too. Hope it helps.
MD