connections interconnecting lifting conveyor assembly 60 and frame 22 as is known in the art lifting adjustment mechanism 56 can be configured in a number of different ways to accomplish its objective of raising and lowering lifting conveyor assembly 60 flapper assembly 58 comprising a hydraulically powered flapper wheel 66 collects the onion plants 12 from lifting bar 54 and coaxes them onto lifting conveyor assembly 60 flapper wheel 66 is preferably made out of rubber or flexible rubber like material to avoid damaging onion plants 12 as they are extracted from field 14 that extends the width of lifting conveyor assembly 60 as flapper wheel 66 rotates around its central axle the paddle like members push the onion plants 12 rearward toward the lifting conveyor assembly 60 in the preferred embodiment lifting conveyor assembly 60 is comprised of a hydraulically driven lifting conveyor 68 first lifting sprocket 70 second lifting sprocket 72 rollers 74 hydraulic motor not shown in fluid connection with pump 50 and protective sidewalls 76 lifting conveyor 68 interconnects first lifting sprocket 70 which can be a cone shaped roller and second lifting sprocket 72 and is operatively supported by rollers 74 in the preferred embodiment lifting conveyor 68 is a hook chain type of conveyor such as those available from acme manufacturing company out of filer id although other types of conveyors could be suitable for lifting conveyor 68 most such conveyors may not be able to withstand any contact with the ground and could be easily damaged in the preferred embodiment one out of every fifth or sixth bar is raised to support the onions 12 as they are transported up lifting conveyor 68 the use of.