I have an 8X4 planter box that I have used as a chicken run for about a year and have never cleaned it, just added hay to the floor of it if it got muddy. It is exposed to the outside. I was thinking about moving the chickens to the planter box next to it and using the box that they pooped in for a year as a veggie garden. All I was gonna do was mix in some fresh hay and leaves and give it a good tilling. Do you think that would be ok, would it be too much manure and cause burn, do I need to do something else? Any help would be great.