THE AG PILOT HAD BEEN SPRAYING COTTON FIELDS FOR ABOUT AN HOUR, AND WAS PERFORMING ANOTHER PASS. HE REPORTED 'ROLLING AND TURBULENT' WINDS NEAR THE TREE LINES. AS HE PULLED THE STICK AFT TO ARREST THE SINK RATE, THE AIRCRAFT CONTINUED TO DESCEND. THE LANDING GEAR BOGGED DOWN IN THE COTTON AND THE AIRCRAFT CONTACTED THE GROUND, RESULTING IN STRUCTURAL DAMAGE TO THE AIRFRAME. THE PILOT REPORTED THAT JUST PRIOR TO THE COLLISION, HE LOST ABOUT 20 KNOTS OF AIRSPEED DUE TO WIND SHEAR.