The pilot reported that, during a soft-field takeoff from a private grass airstrip, he applied slight aft pressure to the yoke to lighten the load on the nosewheel. The airplane became airborne, but while in ground effect, the left wing dropped about 10º, and the left main landing gear contacted the runway. The airplane settled back on the ground pointing about 30º left of the runway heading. The airplane then departed the runway to the left and ground looped, during which the left landing gear collapsed. The airplane slid backward and came to rest upright on the field adjacent the airstrip. The airplane sustained substantial damage to both ailerons. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. The pilot added that the airplane's weight and balance were within the operational limitations in the Pilot's Operating Handbook. The automated weather observation system located on an airport 18 nautical miles (nm) south of the accident site reported that, about 17 minutes before the accident, the wind was from 90º at 5 knots. An automated weather observation station located on an airport 22 nm southeast of the accident site reported that, about 14 minutes before the accident, the wind was from 110º at 3 knots. The airplane departed from runway 26.