The glider pilot was seriously injured during an off-field landing. The pilot reported that while maneuvering near a suitable landing area the glider encountered an area of sinking air. The pilot stated that instead of landing in the available open, uncultivated field, he elected to maneuver toward a "better looking cloud a mile or so further west and away from my selected landing field." The pilot reported that, "On the way to this cloud I encountered strong sinking air, which often surrounds a thermal." The pilot stated that he eventually elected to turn back towards where he came from, but encountered "even heavier-sinking air" and that he did not have enough altitude to glide back to his selected landing site. The pilot reported that the only landing areas available at that time were established cornfields. The pilot stated that he "made a carefully controlled descent into the corn, so not to put one wing in first and cause a cartwheel landing." The pilot reported the glider traveled about 40 feet into the corn crop before the airplane decelerated and dropped "vertically from about 3 to 4 feet." The pilot fractured three vertebrae during the hard landing. The glider sustained minor damage, limited to the gear doors.