Your best bet is to use liquid fertilizer, and keep them off it till it has soaked into the ground, and dried off on the leaves a bit. I do use the pelleted fertilizer, and the chickens do pick it up sometimes. I'm sure it's not good for them... But... it's not always possible to keep them from going where you don't want them to go. I've heard that salt can be deadly. One thing I'll not use any where on my property is herbicides.