The pilot stated the chute on the powered parachute fully inflated during the takeoff from a grass field. Once inflated, the chute began to oscillate, and the aircraft began to bounce. The pilot increased the flare of the chute to get the wheels off the terrain. Once airborne, the landing gear contacted a bean crop located at the end of the grass field. The aircraft continued to gain altitude, and as the pilot decreased the flare, the aircraft began to lose altitude, and, once again, the landing gear scraped the bean crop. The pilot increased the flare and the aircraft began to slowly gain altitude. As the aircraft approached an irrigation boom, the pilot initiated a left turn during which he lost control of the aircraft and it impacted the field. The aircraft sustained broken structural fuselage tubing, and the pilot sustained serious injuries. The pilot reported that he suspected the adjustment knot on the steering line slipped, which resulted in the loss of control during the turn. A witness reported that the powered parachute did not fully inflate and the aircraft did not become airborne until it was three-quarters of the way down the airstrip.