Ever been close to a manure lagoon?

No, but I camped next to a chicken ranch once at Abbotsford, BC.
Hardly noticed it in the evening, but next morning the wind had
shifted - and omigawd what an awful smell!

More recently, the county raised pigs at their honor farm right next
to the airport where I was based. The wind was usually blowing the
wrong way.....

David Johnson