There are diverging opinions regarding chicken manure. One of the downsides that I learned of from an older experienced farmer in France is that while it may increase soil fertility in the short term it may actually decrease soil quality in the future… He said that there is a saying in France that chicken manure “enriches the father and impoverishes the son” .@fakei Interesting! I knew the droppings from hens is good fertilizer for plants.
It is often too rich for certain plants and it is a pollutant to waterways, which is usually the case of most animal manure being used on the land. There are also health risks associated with its use such as Salmonella poisoning. It is possible and preferable to garden using Veganic methods.

