I keep a few chickens and allowed them to run in a fenced area approx 15x 50 foot. We live near the water and a water rat was coming out and taking everything from my old garden so I decided to move the garden to the area where my chickens were. It is further from the water and fenced which I hoped would keep the water rat out. It did, but the garden did poorly. There is plenty of sun. I thought the ground would be good as the chickens fertilized it, but it did badly. Too much fertilizer? What can I do to help? Chickens not in there for a year now.
How long were the chickens gone when you planted last year? It's possible that the manure had not fully composted and burned the plants.
Read through this page's information on composting manures: https://extension.umd.edu/hgic/plants/prepare-your-soil
We'd recommend that do a soil test of the garden. The pH may be too high or low. For how to collect samples, what to test for, and labs to send it to, here is our webpage: http://extension.umd.edu/hgic/soils/soil-testing
Now that the yard has been free of chickens for a year, the manure should be composted. You should have better success this year--still get that soil test though.