On December 4, 2004, about 1500 Pacific standard time, a Maule MX-7-235, N420CD, registered to and flown by the pilot as a 14 CFR Part 91 personal flight, landed hard in an open field about 8 miles south of Hermiston, Oregon, and collapsed the landing gear. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft was substantially damaged and the private pilot, the sole occupant, was not injured. The flight departed from Hermiston, about one hour prior to the accident. In a written statement, the pilot reported that after flying around the local area for about one hour, he decided to land in an open field on his parents property. The pilot reported that he set-up a normal approach to land over a 30 to 40 foot obstacle. After clearing the obstacle, he lowered the nose of the aircraft, then flared for the landing. The flare did not adequately arrest the descent rate and the aircraft touched down hard subsequently collapsing both main landing gear. The aircraft slid on its belly for about 100 to 150 feet before coming to rest. The pilot reported that the landing surface was an open cow pasture approximately 1,200 feet in length. The surface was smooth and firm. The wind was light and variable with an unrestricted visibility.