And IMHO if you drink beer trousers without a fly aren't that great a choice for 'down the boozer'.
Seems like climbing trousers these days are all super-expensive tracky-bottoms. Surely a fly and a zip pocket to put stuff like car keys in you don't want to leave in your bag aren't too much to ask for.
Cotton is reckoned to use about 25% of the worlds insecticides and about 10% of the total artificial fertilisers in its production. It only takes up about 3% of the worlds total agricultural area though so the organic production methods is supposed to help reduce these numbers and help the environment.