On March 14, 1996, at 1100 hours Pacific standard time, a Burkhart Grob Flugzeugbau, G102 Club Astir IIIB, N851BG, collided with a berm while making an off-airport landing during a personal flight from the Douglas County Airport, Minden, Nevada. The glider was substantially damaged, and the airline transport pilot was not injured. Visual meteorological conditions existed. The flight originated from Minden at 1020. The pilot reported that he received a weather briefing which indicated the possibility of ridge lift. Following what he described as a normal takeoff and climb, the pilot released from the tow plane when he was at 7,000 feet mean sea level (msl), about 4 miles from the 4,718 foot msl airport, and 2 miles from the ridge. The pilot further reported that he encountered some ridge lift, but descended to 6,200 feet msl. Then, a fairly substantial sink rate was experienced and he realized that he was not high enough to return to the airport. The pilot made a forced landing in a soft, muddy dirt field, about 0.25 miles from the airport.