hey a friend of mine used only bat and seabird guano for his entire grow, and he did exactly what you are talking about. he would add the guanos to a gallon of water, put the cap back on the gallon and let them sit for a few days. of course shake it up before you actually use it to make sure everything is nice and mixed in there, but he had GREAT yields, and it was only his first grow. I personally use teas, but my yields are only slightly better than his were, and i think its mostly because i use some extra ingredients and have a little more experience. basically, if that is your only option for whatever reason, it will work very well. I would still go with this over top dressing the soil because you have much more control. you can choose more/less guano for each individual feeding and have the option to feed straight water every couple feedings. oh- dont forget to ph the solution before you feed your plants!