Indentured servitude, a workforce confined to the borders of the plantation by armed guards, being "paid" by being allowed to live in unlit huts and drink water from the pig trough. Violations punished by summary execution and burial in an unmarked pit.
This sounds like a historical account of life on a colonial plantation of the 18th century, but is actually the description of the sugar industry, today, in the Dominican Republic. The new film "The Price of Sugar," about the abuses of Hatian migrant workers on a Dominican sugar plantation, tells the story of a Catholic priest trying to organize the workers. (IMDB, NPR story)
Of course, the larger issue here is that biofuel production is dependent on exactly this industry. As long as biofuels are an over-subsidized boondoggle, then industrially raised corn is fine. Well paid farmers driving their John Deere tractors don't present a human rights problem. But as EROEIs decline and we increasingly turn to human labor for biofuels, classical plantation problems will likely resurface in force.
It may be quite some time before Americans are enslaved in the production of fuel for other Americans' cars, but are we so racist/nationalist/blind to accept the enslavement of others to these ends?