Hoeing (and /or mulch) is essential in organic agri- and horticulture. And very time consuming. For a garden still succeed, but for a field (corn, beets) suitable material provides a lot of time savings.
WielSchoffelI have a (hand) hoe made ​​from the front wheel + fork + handlebar of a children's bicycle. Between fork and handlebar, I ordered a half inch tube of about 130 cm. So I can steer the wheel about 2 meter in front of me. 40 cm behind the wheel is in vertical direction to the earth a rectangular tube with a nut welded on a hole. From an old (circle saw) blade I forged hoes of different widths: 12, 20 and 30 cm. The steal of those I can screw stable into the rectangular tube.
With this I can run between the plant rows. At least 10 times faster than manual weeding.
My sowing and planting distances are adjusted to the hoes, about 4 cm wider than their width. So you do not have to aim accurately. Otherwise you’re hoeing your crops also by the speed.
The wheel must be at least 30 cm in diameter, otherwise it is heavy and even stuck in loose soil, and it blocks on thicker clods.
If you give the connection between steering shaft and the ax at about 40 cm. of the axis a kink, so that the short distance to the wheel substantially is parallel to the ground state, it does work easier.
It will have to do I guess something with the direction of the applied forces.

Previously, there were even made ​​such things, usually with two iron wheels, where crop rows continued between. Behind each wheel, there was a knife. Which could be further or closer mounted together (usually slight V - shape, point to the 'driver '). Each wheel had a wooden rod. To the top all of which two were then twice connected to each other.

I had for my bike hoe or hoe barrow (with one wheel and two handles it also looks a bit like a wheelbarrow) also made
a cultivator or pull tooth: in succession hehind each other 1, 2 and 3 to the front pleated teeth,

and a hiller to ridge ground potatoes: a pointed, 15 cm high V I drove forward with the point between the rows. (Like a double sided plough. Discs can do the same job.)