When some students go to college this fall, they will do so at a campus surrounded by farms and fields. The U.S. Department of Agriculture is working with colleges in rural areas, providing funding to keep them up to date and competitive with larger, urban-based institutions. U.S.D.A. Deputy Undersecretary Doug O’Brien was at Fulton-Montgomery Community College in the town of Johnstown yesterday to dedicate a new residence hall at the school, Raiders Hall. It was built with the help of 11-point three million dollars from the U.S.D.A.