We took down an old chicken building, which held thousands of chickens 10 yrs ago and within the last two years have had a garden in the place where the building was. Is that chicken manure very potent being it was so long ago?
Is Old Chicken Manure Healthy to Use?
Certified GKH Gardening Expert
If it's been sitting awhile then it should be safe to use. Fresh chicken manure is extremely high in nitrogen and will burn plant seedlings, so you want the manure to be well aged prior to planting in soil that's been amended with it. You can also choose to compost it. This article will help: https://www.gardeningknowhow.com/composting/manures/chicken-manure-fertilizer.htm