During a balloon flight, the pilot advised the two passengers to face in the direction of travel and to bend their knees when they land. The wind at the time of landing reportedly gave the balloon a nine mph groundspeed. The pilot also indicated to the passengers that momentum would propel the basket occupants forward during the landing. The pilot executed a touch down into a ditch alongside a highway after making a landing approach over a soybean field. The basket subsequently laid over on its side. One passenger sustained a serious ankle injury during the hard landing. The pilot and the other passenger were not injured and the balloon was not damaged. According to the pilot, the injured passenger indicated that her knees were bent before landing. The pilot stated that he would instruct future passengers to point their toes in the direction of travel and add a question to his passenger questionnaire to inquire if a passenger had a medical condition that would cause the passenger to have weak bones.