On May 29, 1998, at 1445 central daylight time, a Grumman G-164A agricultural airplane, N8629H, was substantially damaged when it collided with trees and terrain while on takeoff near Iowa, Louisiana. The non-instrument rated commercial pilot, sole occupant of the airplane, was not injured. The airplane was owned and operated by O'Brien Flying Service Inc., of Iowa, Louisiana. Visual meteorological conditions prevailed for the aerial application flight. No flight plan was filed for the Title 14 CFR Part 137 flight. The local flight was originating at the time of the accident. According to the operator, the airplane was operating from a 2,300 foot long grass airstrip locally known as Robertson's strip. Prior to takeoff, the airplane was loaded with 1,600 pounds of fertilizer to be applied on local rice fields. The pilot stated in a telephonic interview with the NTSB investigator-in-charge, that during the takeoff roll to the north, with a 5 to 8 knot crosswind from the west, "the tailwheel would not come up." The pilot added that, as he got closer to the trees at the departure end of the strip, "he started to release some of the load in the 300 gallon hopper in an attempt to get airborne." The pilot further stated that the airplane got airborne, but the impact with the top of the 10 foot high trees decelerated the airplane; subsequently, the main landing gear impacted a 3-foot high rice levee, separating the left main landing gear from the airframe. In the enclosed narrative portion of the NTSB Pilot/Operator Aircraft Accident Report, the pilot amended his previous statements by stating that after rolling for about 1,900 feet during the takeoff roll, the engine lost power, so he started dumping his load of fertilizer to lighten the aircraft. After becoming airborne, the pilot elected to return to the operator's 3,800 turf airstrip where emergency equipment was standing by. While landing on runway 21, the partially attached right main landing gear separated from the airframe and the airplane skidded on its belly, nosed over, and came to rest in the inverted position. The operator reported that both right wings, the left lower wing, the empennage, and the attaching points for both main landing gear assemblies sustained structural damage. The pilot stated that he estimated that at the time of the accident, the temperature was near the century mark, and the winds were from the west at 5 to 8 knots. The NTSB investigator-in-charge estimated the density altitude at 2,650 feet. The reason for the reported partial loss of engine power could not be determined. The operator stated that takeoff performance data is not available in the current aircraft pilot's operating handbook. He added that his son had been flying a similar airplane loaded in the same manner along with the accident airplane. He added that if the engine would have not loss power, the accident would have never occurred.