Many farmers are subsidised specifically so that food is over-produced in most years, specifically to ensure than in bad years people don't go hungry.
Corporations may indeed be taking advantage of this, demanding prices so low that the farmers don't get the benefit of those subsidies. However:
> buy the stuff and sell it at a premium later
Is the point of a futures market. Futures let people trade a thing before they even know how supply and demand will balance, guaranteeing a price for the producer and letting them plan purchases of machinery and maintenance, with the risks (in bad years) and profit margins (in good years) going up the supply chain.
Corporations may indeed be taking advantage of this, demanding prices so low that the farmers don't get the benefit of those subsidies. However:
> buy the stuff and sell it at a premium later
Is the point of a futures market. Futures let people trade a thing before they even know how supply and demand will balance, guaranteeing a price for the producer and letting them plan purchases of machinery and maintenance, with the risks (in bad years) and profit margins (in good years) going up the supply chain.