Philco, the USA subsidizes agriculture to the tune of about $20 billion dollars a year.  With a significant portion for corn and soybeans.  The corn subsidies are not for human food consumption.  And yes the US politicians do not have a backbone to stand up to the ethanol corn lobby.  As well the US subsidizes the dairy industry for about $250 million a year.  However, the point the vast majority of the subsidies do not go to the dairy industry.  Again, as I said before any negotiations would require the removal of the subsidies.  The Corn subsidies do not appreciably affect Canada 
Hopefully YOU understand.