My understanding is that amber box subsidies are any subsidies that affect the price or production of an item, and the U.S. proposal is to cut ours by 60% if the EU cuts theirs by 83% (the reasoning being that their subsidies are higher than ours to begin with). I have never heard of the U.S. government paying farmers to keep their fields fallow in the name of environmental conservation (can you imagine someone argue that it is somehow conservative?--hint), and I'm not about to go searching the 'net for that sort of information unless you pay me. Here's a suggestion: why not make your point anyway?
My opinion is that a subsidy in the name of the environment is still a subsidy (the operative fact being that checks are being cut), whereas banning production (say, to save the snail darter) is not, because no money changes hands.