To clarify, removing tariffs and agricultural subsidies might not affect our overall agricultural output much (I wouldn't want to make a prediction on that) but it would lower the cost of goods which were previously subsidized with taxes or tariffs.
> Not to mention if we become an importer because of this, we could outbid other nations and instigate famine in the poorer nations.
It's worth pointing out that almost all economists of all political leanings are opposed to agricultural subsidies (it's one of the rare political things economists agree on) and one of the commonly cited reasons is that buying food produced by third-world economies at a true market price would be a natural and valuable step in helping those countries develop and grow out of poverty. The number of powerful people (including people who would normally give lip service to free markets) who, when confronted by this consensus among economists, basically don't give a shit is... disheartening.