On April 9, 1994, at 1430 central daylight time, a Schweizer G- 164, N3628T, was substantially damaged during takeoff near Mount Bellvue, Texas. The commercial pilot, who was not injured, was not on a flight plan and weather was visual meteorological conditions. The pilot stated in the pilot/operator report that he was taking off from a runway, specifically prepared for agriculture operations, when the aircraft began to drift right. As the aircraft drifted right it entered a "soft area" and nosed over to the inverted position. An examination of the aircraft revealed that it was loaded with rice seeds. The pilot reported that the winds had begun to vary in direction at the time of the accident and were marked with "strong gusts." He further referred to a "combination of wind and runway conditions" as the reason for his loss of control.