According to the pilot, during the landing on a grassy area that was parallel to the paved runway, the airplane touched down and impacted a ditch near an intersecting taxiway. The airplane became airborne, touched down on the other side of the intersecting taxiway, bounced again, and then landed hard on the nose gear, which resulted in substantial damage to the fuselage and subsequent collapse of the nose landing gear. In a telephone interview the pilot stated that the ditch was approximately 200 feet from his initial touchdown point and that he regularly lands on the grass, in the opposite direction, in order to minimize the wear on the main landing gear tires. No preaccident mechanical malfunctions or failures were noted with the airplane that would have precluded normal operation.