I have thousands of seedlings to plant and it would be backbreaking work to do it with a small shovel on hands and knees or to bend over and plant each one. In my research into broadacre permaculture systems I came across a tool known as the "Pottiputki" which is a reforestation tool used to plant seedlings on a large scale. Unfortunately, I could not find one for sale in the USA, nor does anyone seem to ship them here. They also cost $300 and the shipping from Europe would be a mint so I went ahead and made my own from off the shelf parts at Lowes for about $60.
The main body consists of a stick of 2" electrical pipe (emt) with the digging end made from heavy duty galvanized 2" rigid electrical pipe.
I marked the 2" rigid with electrical tape to make the cut for the main body of the digging end and cut it with a 4" grinder with a cut off wheel. A miter saw with a metal blade would have been a better tool for the job.
After fabricating the main body of the digging end, I test fitted it onto the 2" emt pipe. I split the digging end at the narrow and spread it open slightly for it to fit over the emt.
I used the other half of the digging end cut off to make the opening part of the digger. I then welded on a length of 1" bar stock for the foot pedal and began to shape it to go around the main body of the tool.
Here is the business end of the tool with the shovel body welded up and the opener/foot pedal assembly bolted in place with short carriage bolts. I used a 110v wire welder that I got on ebay for $100 and, as you can see, you don't need to be the world's best welder to make it work. Below is a video showing the final bits and pieces and some tips to make it all work.