It's extremely complicated. One reason for keeping prices high this season is to prevent loan defaults from the farmers/producers in the fall. So one part of the federal government may spend another $40mil affecting the sugar market (high prices this season) to prevent a loan default of $100mil to different parts of same federal government and all of the fallout to those small businesses. Bankruptcy threatens families keeping their farms... as big of a deal as foreclosures for suburbanites.

The loans are based on a variety of factors and have a variety of goals from ensuring that family farms exist (and don't get gobbled by mega-farm corps) to ensuring that we grow certain kinds of crops in this country to ensuring we build better combines. It's very complicated and any 'narrative' that has a single cause or explanation is likely incorrect.