The sport pilot flight instructor reported that while maneuvering during a local instructional flight, he noticed dust forming in a circular pattern within the air near their position. The student pilot, who was flying the airplane, initiated a climbing 180-degree turn towards their point of departure. While approaching a ridge line about 800 feet above ground level, the instructor noted the turbulence was increasing while the airplane started to descend and took control of the airplane. The instructor stated that despite using full throttle, the airplane continued to descend rapidly while "getting forced down by a microburst," prompting him to initiate a forced landing into an open field. The instructor added that due to the low altitude, he was unable to align the airplane with the rows of dirt. During the approach to landing, the airplane "caught some lift" and subsequently entered a "strong down draft" and impacted the ground. Examination of the airplane by the instructor revealed that both wings and fuselage framing were structurally damaged. The instructor stated that there were no mechanical anomalies with the engine or flight control system that would have prevented normal operation.