The USDA Economic Research Service maintains a national Commodity Costs and Returns including estimated annual production costs and returns and published accounts for major field crop and livestock enterprises since 1975.
Another source of simple national and regional cropping costs information from Economic Research Service (ERS). This is a subpart of their Farm Business Economics Briefing Room (featuring current analyses and data of major farm, business, and household indicators). If you have questions or comments, e-mail Bob McElroy.