The pilot stated that prior to departing to a private airport, he called the owner of the airport to inquire about the condition of the turf runway. The owner reported that the runway appeared to be "okay." Upon reaching the destination airport, the pilot conducted two approaches to the runway that were "steeper and faster" than he desired, and he aborted both landing attempts. On the third approach, the airplane touched down approximately 500 feet from the runway threshold. After touchdown, the pilot realized that he had little braking effectiveness, and was unable to stop the airplane. The airplane traveled off the departure end of the runway, and impacted trees, resulting in substantial damage to both left and right wings. Postaccident examination of the airplane revealed no evidence of any mechanical malfunctions or failures. The pilot and a Federal Aviation Administration inspector reported that, although the grass on the runway appeared normal from the air, there was a layer of ice underneath due to rain and below-freezing temperatures for several days prior to the accident, resulting in slick runway conditions.