some kind of planter
My guess is that it is meant to have two wheels, and is the rear-end off of either a tractor, or a Model-T tractor conversion, or something similar.
You could probably adapt it to your Kubota to prevent flat tires.
I might be wrong, but I think it is the remnants of a Macormick Deering sickle mower. The hand control was used to raise and lower blade,and the foot pedal was used to engage/disengage. They were made to be horse drawn, later convertrd to tractor pulled. All power was derived from the one wheel, then transfered by way of the gears to the cutter bar and the lift mechanisim.
The sickle mowers I'm seeing online appear to be much lighter. But, that may be a good direction.
What about this "Oat Binder".
Binding the Oats | Living History Farms
It may be a pretty extraordinary find, if only it was a little more complete.
I tend to agree with M E Race that it is the remnants of a horse drawn sickle mower. I haven't seen one in many years, but I believe this could be parts of one.
Part of a corn harvester. .?:D
Part of a corn picker or a grain binder.
I'm going with grain binder also. I'm guessing that the worm drive is for the knotting mechanism. (every bundle was twine tied) Looks like there are several quadrants for adjusting levers and also the foot pedal consistent with a binder. Could be wrong, of course. Very interesting
I was thrilled as a farm kid to get to stay home from school and drive the tractor pulling the binder while my dad rode on the binder to adjust the levers for changing field and crop conditions. Wasn't as thrilled with the many hours of shocking that came later. Our binder was a later model with PTO drive.
Edit: Something I've never been able to figure out is how they run PTO and hydraulics off of the horses.
Grandpa and I just restored a McCormick Deering horse drawn sickle mower last summer. It looks nothing like what you have there. On the sickle mower, the drive gears go through an axle tube, and a gear box. Yours has the ground engaging wheel, a big gear with a chain, then a smaller gear, turning a worm gear. All those wood slats piled up in your second picture lead me to a conveyor somewhere.