The pilot intended to spray a cotton crop. A power line crossed the area at an oblique angle, and at the point where the aircraft passed under the wire there was a head ditch one metre high, dividing two paddocks. On the first spraying run the pilot misjudged the clearance under the wire and the mainwheels struck the top of the ditch. The aircraft remained controllable and an uneventful landing was subsequently carried out at the destination aerodrome. Damage was confined to the gear truss points and shock absorbers.