It's been an agribusiness ploy for years to tell farmers the answer to their low price problem is to export more and find new uses. (They don't mention that this emplies we're aiming to make food scarce, which NOBODY would want.)
Farmers themselves don't export anything, or make ethanol either, so what they were saying is you farmers go ahead and plant as much as you can (oh, and we'll encourage the same all over the world with our new technologies), and leave things up to the market. So the supply is always increasing at the expense of the environment here in Iowa and in Brazil, etc. while the only thing that increases demand is the fact the commodities are so cheap. They also use the renewable fuels standard to keep up demand. If it wasn't for that, who knows how low prices would be?
The system is designed for extraction to produce cheap commodities. All the "subsidies" have been a scam based on fake economics. A diversified farm that has livestock and needs oats for feed and bedding, hay and pasture would be the only way to prevent erosion and water polution. When farmers get "subsidies," the actual market prices of corn and soybeans can still be very low. Therefore, it becomes cheaper to feed livestock in huge corporate confinements and feedlots rather than doing it on the family farm with the sound crop rotation. The true costs, present and future, are not being included in the price of the commodities, so the empire can expand and increase corporate profits. So agribusiness uses taxpayer dollars to make it look like farmers are on the dole, while the family farm system and rural communities are destroyed worldwide.
The billions spent on subsidies pale in comparison to the loss to the economy and the soil and water resources. Farmers and peasants all over the world flock to cities (usually shantytowns with no running water or sewers), and become shithole countries like we're becoming.