THE PIC WAS PRACTICING T&G LANDINGS TO A SOD STRIP AND HAD COMPLETED SEVERAL PRIOR TO THE ACCIDENT. ON THIS ATTEMPT, THE PIC STATED HE MADE A 3-POINT LANDING TO A WHEAT FIELD HE MISTOOK FOR THE SOD LANDING STRIP. THE GROUND WAS SOFT AND UPON TOUCHING THE LANDING GEAR BECAME MIRED, AND THE ACFT NOSED OVER INVERTED. THE WHEAT FIELD BORDERS AND PARALLELS THE SOD STRIP HE HAD BEEN USING.