help?

I have an area I used to have chickens, I am wanting to bring a dog to that area and use the very nice K-9 house my husband built a few yrs ago as a template for the dogs we ended up using for the chickens and its too heavy to move , the area is about 40x40 and perfect for the dog but I am afraid to expose her to the chickens area, the chickens have been gone since early spring and I have bleached the coop (dog house) but does anyone know how long the ground might keep an organisms? or what I can use to kill any lingering issues?
Thank you
Deb Dikeman
www.twinwillowskings.com