On October 21, 1994, at 0945 central daylight time, an Air Tractor AT-301, N8523S, was substantially damaged while manuevering near Lubbock, Texas. The commercial pilot was not injured. Visual meteorological conditions prevailed for the aerial application flight. During an interview, the pilot reported that he was spraying cotton plant defoliant "close to the ground" in an effort to increase its effectiveness. During an application pass, the aircraft struck stationary irrigation spraying equipment with the left main landing wheel and the propeller. He stated that after the left main landing wheel made contact, the aircraft started to nose down and the propeller made contact with the wheels of the equipment. The engine then "exploded." The pilot maintained control of the aircraft and glided to a forced landing in a stripped corn field approximately 200 yards from the initial impact with the irrigation equipment. The pilot further stated that he was "tired after many days of spaying", and that the irrigation equipment was difficult to see because it "blended into the white cotton that was 90% open." Examination of the airplane at the site revealed evidence of propeller blade contact on the irrigation spraying equipment. The left main landing gear was sheared from its attachment point and the left wing was structurally damaged during the forced landing.