Why did the federal government establish agricultural price support programs\?

To make sure the supply of food was consistent and reliable thereby keeping food costs low making the general public able to spend money on other things. Secondly it keeps the political climate more friendly when people are happy. Addition: The government initially built bins because there was little on farm storage. Around 1960 they sold these off because as with all government programs they found a lot of grain was spoiling because of poor management. The grain was never kept as a way to make profit, it was only kept to even out supply and demand. These days it is done with a myriad of programs: On farm storage loans, payments for acres planted, extra payments when the price is too low, and so forth. I would agree with your other answer that ADM, Cargill and others have found ways to profit from the government programs. That is the problem whenever the government tries to fix things, they only cause more problems.